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In recent years, high-entropy alloys (HEAs) have emerged as a novel class of high-performance materials with broad applicability. Currently, one of the most attractive HEA-related research areas involves incorporating an appropriate amount of certain alloying elements into HEAs to regulate their composition and microstructure and enhance their corrosion resistance. This article classifies the added elements reported in recent years and systematically reviews the effects of different types of alloying elements on the corrosion behaviors in different aqueous solutions. A correlation between the composition, microstructure, and corrosion resistance of HEAs was established to reveal the underlying mechanisms. Finally, research directions of elemental addition in HEAs are suggested for the future development and application of corrosion-resistant HEAs. • This review classifies the added elements in HEAs reported in recent years. • Effects of different types of elements on the corrosion behaviors were summarized. • Correlations between composition, structure, and corrosion resistance were discussed. • Future directions of elemental addition in HEAs were suggested. [ABSTRACT FROM AUTHOR]

In this study, Bi, Sb, and Ni were incorporated into Sn3.0Ag0.5Cu (SAC305) solder to enhance its properties. The composite solders SAC305- x Bi-2.0Sb-0.1Ni (x = 2.5, 3.0, 3.5 wt%) were systematically investigated for their microstructure, thermal characteristics, wettability, thermal aging behavior, intermetallic compound (IMC) formation at interfaces, and mechanical properties of solder joints. The results demonstrated that the combined addition of Bi, Sb, and Ni effectively suppressed IMC growth within the solder matrix, leading to microstructure refinement. Increasing Bi content expanded the spreading area, thereby enhancing wettability. During thermal aging, the growth rate of solder joint interfaces decreased as the Bi content increased up to 3.5 wt%. Electron backscatter diffraction (EBSD) analysis indicated that these alloying elements reduce slip and deformation in the Sn matrix of SAC305-3.5Bi-2.0Sb-0.1Ni solder. Moreover, the tensile strength of solder joints consistently increased with the incorporation of these elements. • Adding Bi, Sb, and Ni to SAC305 solder refines microstructure and improves overall properties, including wettability and thermal properties. • Increased Bi content in the solder alloy enhances spreading area and wettability, while broadening the melting range and reducing subcooling. • Higher Bi content decreases the growth coefficient of the solder joint interface during heat aging, forming a "Bi barrier layer. • The alloying elements increase the tensile strength of solder joints, with improved resistance to slip and deformation, transitioning to a mixed fracture mechanism. [ABSTRACT FROM AUTHOR]

In this study, SAC305-0.1Ni and SAC305-0.1Ni- x Sb (x = 1.5 wt %, 2.0 wt %, 2.5 wt %) composite solders were fabricated by incorporating Ni and Sb alloying elements into Sn3.0Ag0.5Cu (SAC305) solder. A comprehensive investigation was carried by utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), microhardness tests, nanoindentation, transmission electron microscopy (TEM), and a universal mechanical testing machine. The effects of Ni and Sb additions on microstructures, thermal properties, wettability, mechanical characteristics, as well as thermal aging, interfacial growth, and mechanical properties of welded joints were systematically explored, and these results were compared with SAC305 solder. The results indicated that the incorporation of Sb and Ni enhanced the microstructure of the solder alloy through the formation of (Cu, Ni) 6 Sn 5 and SnSb phases, leading to a 23.90 % increase in the solder wetted area. Additionally, the formation of (Cu, Ni) 6 Sn 5 and SnSb intermetallic compounds (IMC) increased resistance to dislocation motion, thereby enhancing the mechanical properties of the solder alloys in comparison to SAC305 solder. The creep resistance of the solder alloys was significantly improved, with a corresponding 49.19 % increase in Vickers hardness. During the thermal aging of solder joints, the interfacial growth coefficient decreased, with the SAC305-0.1Ni-2.0Sb joints exhibiting the lowest value at 0.0185. Furthermore, the co-addition of Ni and Sb consistently enhanced the mechanical properties of the welded joints. The average tensile strength of SAC305-0.1Ni-2.0Sb joints reached 77.87 MPa, which represents a 28.45 % increase compared to SAC305 joints. As the Sb content increased, the fracture mode transitioned from brittle fracture to ductile fracture, and eventually to a mixed ductile-brittle fracture. • SAC305-0.1Ni and SAC305-0.1Ni- x Sb composite solders were prepared, systematically exploring the effects of Ni and Sb on microstructure. • The incorporation of Sb and Ni enhanced the microstructure of the solder alloy, significantly improving the mechanical properties of joints. • The creep resistance of SAC305-0.1Ni-2.0Sb joints increased, with average tensile strength rising to 77.87 MPa and fracture modes improving. [ABSTRACT FROM AUTHOR]

The effects of a C vacancy (V c) on the position preferences of alloying elements Mo, Ti, Ni, Si and Ag at the Al/TiC interface are studied using first-principles calculations. The ideal work of adhesion is calculated to evaluate the alloying elements that affect the interfacial strength with or without V c. The formation heat is studied to obtain the site preferences of the alloying elements. The results show that V c changes the most preferable substitution site of Mo, Ni and Ti except Si and Ag. Mo and Ti are favorable to enhance the interfacial bonding strength no matter whether V c exists in the Al/TiC interface, in which Mo has the best reinforced effect. Ni and Ag have the opposite effect. The improvement in interfacial strength is ascribed to the increased the charge accumulation between the alloying atom and the C atoms. Furthermore, generalized stacking fault (GSF) energies are calculated. V c increases the GSF energies barriers of Al/TiC interface with alloying solutes. Alloying elements of Mo, Ti, Ni, Si and Ag and V c contribute to increasing the brittlement of Al/TiC interfaces based on the Rice criterion. It is meaningful to the development of composites with better mechanical properties. [Display omitted] • Mo and Ti are favorable to enhance the interfacial bonding strength no matter whether V C exists in the Al/TiC interface. • Ni and Ag have the opposite effect. Ag and Ni exhibit the weakening effect on the interface. • V C increases the GSF energies barriers of Al/TiC interface with alloying solutes. • Alloying elements of Mo, Ti, Ni, Si and Ag and V C contribute to increasing the brittlement of Al/TiC interfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sc, Ti, Y, Zr, and La could sharply reduce the ES barriers of Ag(1 1 1) step edge. • Energies of end-state systems doped by Sc, Ti, Y, and Zr rise during exchanging process. • La could decrease the energies of end-state systems and sharply reduce the ES barriers. The Ehrlich–Schwoebel (ES) barriers can significantly affect the growth mode of Ag films. In this paper, the effect of surfactant atoms on the ES potential barriers of Ag(1 1 1) is investigated by first-principles calculations. The results show Sc, Ti, Y, Zr, and La could sharply reduce the ES barriers. Furthermore, the energies of the doped systems all decrease during exchanging process except the systems doped by Sc, Ti, Y, and Zr. Therefore, La might be a better surfactant for Ag to reduce the ES barriers and promote the 2D growth. [ABSTRACT FROM AUTHOR]

• Electroless nickel plated alloys were tested in K 2 CO 3 + Na 2 CO 3 and NaCl + Na 2 CO 3. • Latent heat of salt decreases as impurity levels increase due to corrosion. • Nickel plated Monel 400 experienced the most corrosion damage, a 500 µm thick layer. • NaCl + Na 2 CO 3 exposed to MO400 experienced largest decrease in latent heat by 18.1%. • IN601 was best performing alloy. Nickel Coating reduced its corrosion damage. Interactions between electroless nickel plated Inconel 601, Monel 400, and stainless steel 316L alloys with two eutectic salts used as phase change materials, K 2 CO 3 + Na 2 CO 3 and NaCl + Na 2 CO 3 , were investigated at 720 °C (isothermal). The results of this study show that at these high temperatures, which is the target temperatures of the next generation of concentrated solar thermal power plants, these salt phase change materials are highly corrosive to stainless steel, whereas the Inconel 601, a high temperature nickel alloy, was resistant. Monel 400 experienced the most corrosion damage (500 µm thick corrosion layer) and resulted in the salts experiencing the greatest latent heat decrease by 18.1%, as confirmed by Differential Scanning Calorimetry (DSC). IN601 performed the best with an observed corrosion layer thickness of 107 µm, and resulted in one of the salts only decreasing in latent heat by 5.9%. IN601 with the nickel plating has shown improved corrosion resistance over uncoated samples. The thermophysical properties of the salt was measured before and after the exposure tests to demonstrate the significant effect corrosion has on the performance of the salts as a phase change material. Scanning Electron Microscopy (SEM) analysis showed that constituent elements have diffused from the alloy specimens, through the nickel plated layer and leached into the molten sat, which was characterized by Inductively Coupled Plasma- Optical Emission Spectroscopy (ICP-OES). A correlation was found between the corrosion of the specimens, the solubility of the alloying elements and a large decrease in the salt's latent heat properties. [ABSTRACT FROM AUTHOR]

Diffusion of alloying elements in a low-cost third generation Ni-based single crystal superalloy during oxidation at high temperature was investigated. The evolution of oxide layers depended on dominant diffusion of alloying elements at different stages of oxidation. Outward diffusion of Cr, Co and Ni was dominant at initial stage of oxidation, resulting in the formation of (Ni, Co)O and Cr 2 O 3. Diffusion of Al and Ta was restricted in γ/γ' area, but dominant in γ'-free layer. Due to outward diffusion of other elements, passive enrichment of refractory elements, Re, W, Mo and Ta included, caused the formation of mixed oxides layer. Finally, selective oxidation of Al led to the formation of (Ni, Co)Al 2 O 4 and Al 2 O 3 layer. [Display omitted] • Evolution of oxide layers depended on dominant diffusion of alloying elements. • Dominant diffusion of alloying elements changed with different oxidation stages. • Other elements diffused outwards led to passive enrichment of refractory elements. • Distribution of Re, W and Mo was mainly controlled by passive enrichment. [ABSTRACT FROM AUTHOR]

Coexisted covalent, metallic and ionic bonds increase difficulty in tailoring the properties of Metal/SiC interfaces by addition of alloying elements. Herein, we revealed the origin of Zr/SiC performance impacted by doping elements (X = Nb, Cr, Fe, Ni and Sn) using density functional theory. We found and clarified weighting of diverse chemical bonds acting on interfaces with different SiC terminations. Interface jointed by strong covalent bonding disadvantages vacancy formation, whereas favors the solution of doping elements, some of which even enhance the interface in turn. Synergy from covalent bonding, ion interaction and structural deformation is important in interfacial adhesion for the other interfaces jointed by weakly covalent bonding. Tensile performance cannot be deducted from the interfacial adhesion as cleavage is ignited from the weakest Zr-X metallic bonds on the side of Zr. An effort of this work aims to establish fundamental rules to help survey and improve Metal/SiC interfaces by screening alloying elements. • We identified weighting of diverse chemical bonds in different SiC terminated interfaces containing alloying elements. • Interface with strong covalent bonds favors the solution of doping elements, some of which enhance the interface in turn. • Structural deformation, covalent and ion bonding all determine interfacial adhesion with weakly covalent bonds. • Tensile performance lies on the weakest Zr-X metallic bonds, which cannot be deducted simply from the interfacial adhesion. • Nb is the best among the doping elements from the viewpoint of stabilizing the interface and the mechanical properties. [ABSTRACT FROM AUTHOR]

Austenitic stainless steel 316 L, a typical face-centered-cubic (FCC) iron alloy, demonstrates great potential as structural materials in nuclear plant. However, liquid metal (Pb and Bi) embrittlement (LME) constitutes the major bottlenect in its wide application. In this work, first-principles calculations are conducted to reveal the influences of Cr, Mo, Ni, Pb, and Bi on magnetic property, surface energy, stacking fault energy, ductility, as well as electronic structure of FCC Fe under the magnetic ground state of antiferromagnetic double layer (AFMD). It is discovered that the addition of Ni could considerably increase the ductility of FCC Fe, while the effects of Cr and Mo on the increase of ductility of FCC Fe seem much smaller. On the contrary, both Pb and Bi significantly reduce the ductility of FCC Fe. Such a large decrease is mainly attributed to the more reduction of surface energy than that of unstable stacking fault energy as well as a more directional and weaker chemical bonding. The derived results could provide insight into the influence of alloying elements on the various properties of FCC Fe. [ABSTRACT FROM AUTHOR]

Abstract The contamination of aluminium streams during the different life cycle stages by alloy mixing and/or accumulation of foreign elements, in combination with the limited melt purification options during remelting, represents an important limiting factor in recycling. Consequently, in secondary aluminium production, primary aluminium is used to dilute the concentration of the residual elements, and alloying elements are added to adjust the composition to the target alloy specifications. However, adding elements, for which their refinement in a subsequent recycling step is problematic, results in permanent down-cycling or 'quality losses'. Hence, it is crucial to more efficiently control the composition of the metal streams prior to remelting. This article focuses on the aluminium cascade recycling chain and presents a Monte Carlo-based decision-support tool aiming to: i) identify all feasible clustering solutions per case based on input/output analysis; ii) quantify their environmental effect, and analyze the trade-offs; iii) consider scrap composition uncertainty/variability. Results reveal that primary resource additions can be minimized by optimizing metal sorting, and thus closing the recycling loop more effectively. Case studies are presented to illustrate the different functions of the tool, including examination of the Pareto front, and evaluation of the 'recyclability' of a scrap stream or a sorting solution into different alloy systems. Graphical abstract Image 1093 [ABSTRACT FROM AUTHOR]

Highlights • Solar energy has a great potential in high temperature process as the production of ferroalloys. • We proposed the synthesis of silicon-calcium using concentrated solar energy. • Silicon-calcium was obtained from mixtures of silicon and calcium carbonate. Abstract The production of silicon-calcium alloy is energy intensive (>10,000 kWh/t). This means that energy cost has a relevant influence in the price of the alloy. The utilization of concentrated solar energy in the synthesis of silicon-calcium alloy is proposed in this paper. Metallurgical quality silicon and limestone are used as starting materials (25 wt.%, 50 wt.% and 75 wt.% Si). After a 12 min treatment under power values of around 1 kW and without using special atmosphere, silicon-calcium was detected in all samples, although mixed with the products of reaction (Ca 3 Si 2 O 7 , Ca 10 O 25 Si 6 , SiO 2). This last question means that there was not proper separation metal-slag, and it should be improved in future investigations. However, the basic knowledge presented in this paper could be of great interest for an industrial process based on the solar energy. This way, the energy costs could be reduced, the pollutant emissions could be minimized, and the competitiveness of the ferroalloys industry could be increased. [ABSTRACT FROM AUTHOR]

Abstract Titanium aluminides are excellent materials for light-weight applications at high temperatures. To enhance their creep strength, various alloying elements are added. In this work the effect of 5 at% Niobium (Nb), Tantalum (Ta) and Zirconium (Zr) on the creep properties of ternary Ti-44Al-5X (X = Nb, Ta, Zr) with a fully lamellar microstructure, is systematically studied. These alloying elements have a high solubility in titanium aluminides, and show a different α 2 /γ partitioning behavior as well as a different influence on the lattice parameters of both phases. The average interface distance between the α 2 - and γ-phase is adjusted to about 300 nm by the cooling rate to evaluate the influence of the three alloying elements. The creep tests reveal that all three alloying elements increase the creep resistance of titanium aluminides, particularly Ta and Zr. Ta seems to extend the pronounced primary creep regime, whereas Zr seems to reduce it. The alloying elements decrease also the lamellar spacing compared to the binary alloy. Microstructural investigations after the creep tests show a beneficial effect of the alloying elements on the microstructural stability during creep exposure, since they retard the discontinuous coarsening rate. [ABSTRACT FROM AUTHOR]

[Display omitted] • 10 2 × 10 2 (1 0 0)Cu/(1 0 0)Mo interface exhibits lower interface energy. • Adhesion work of Cu/Mo interface can improve by some elements such as W and Cr. • Charge accumulations and overlapping states of Cu/Mo interface are raised by W. The influence of some alloying elements on the adhesion work and electron structure of the Cu/Mo interface was investigated by first-principles calculation. The results show that the work of Cu/Mo interface adhesion can be improved as some elements are introduced, such as W, Cr, and Nb. However, some other elements are unfavorable to the interface adhesion work, such as Y and Ni. The overlap region of states is large and the overlap peaks are strong between W-d and Cu-d compared with those between Mo-d and Cu-d. The reverse is true for the overlap states between Y-d and Cu-d. [ABSTRACT FROM AUTHOR]

Weathering steels with different grain sizes (20.0 µm, 3.8 µm, and 0.6 µm) were prepared through a combination of cold-rolling and heat-treatment processes. Their corrosion behaviors were investigated using wet/dry cyclic corrosion tests in 3.5 wt% NaCl solution. The results indicate that grain refinement has a positive effect on the rust layer formation. It accelerates the formation of a more stable, compact, and protective rust layer, along with enhanced enrichment of alloying elements (Cr, Ni, and Cu) as oxide compounds within the rust layer. Moreover, grain refinement shows promise in inhibiting non-uniform corrosion and the formation of "deep-and-narrow" corrosion pits. • Grain refinement expedites the process of rust layer formation on weathering steels. • Grain refinement promotes the formation of alloying element oxides within rust layer. • Grain refinement has the potential to inhibit non-uniform corrosion. [ABSTRACT FROM AUTHOR]

Using a first-principles method in combination with thermodynamic models, we investigate the interaction between rhenium/osmium (Re/Os) and defects to explore the mechanism of radiation-induced Re/Os precipitation in tungsten (W). We demonstrate that radiation-induced defects play a key role in the solute precipitation in W, especially for self-interstitial atoms (SIAs). The presence of SIAs can significantly reduce the total nucleation free energy change of Re/Os, and thus facilitate the nucleation of Re/Os in W. Further, SIA is shown to be easily trapped by Re/Os once overcoming a low energy barrier, forming a W-Re/Os mixed dumbbell. Such W-Re/Os dumbbell forms a high stable Re/Os-Re/Os dumbbell structure with the substitutional Re/Os atoms, which can serve as a trapping centre for subsequent interstitial-Re/Os, leading to the growth of Re/Os-rich clusters. Consequently, an interstitial-mediated migration and aggregation mechanism for Re/Os precipitation in W has been proposed. Our results reveale that the alloying elements-defects interaction has significantly effect on their behaviors under irradiation, which should be considered in the design of W-based alloys for future fusion devices. [ABSTRACT FROM AUTHOR]

In this investigation, the effects of Sn, Cr, and Cu on the precipitation of the second-phase particles (SPPs) in Zr–Sn–0.3Nb–0.3Fe–(Cr, Cu) alloys were investigated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were jointly employed to carry out detailed analysis in the spatial distribution, crystal structure and chemical composition of second-phase particles. Most of the SPPs were homogeneously distributed, with clusters of SPPs occasionally being observed. The content of Sn shows no significant influence on the crystal structure of the SPPs, but the average size of the SPPs decrease as the content of Sn decreases from 1 wt% to 0.8 wt%. Zr(Fe,Cr,Nb) 2 SPPs with C14 and C15 Laves structures were observed in the Cr-containing alloys, while in the Cr-free alloys, in addition to the Zr-Nb-Fe phase, the existence of Zr-Fe phases was confirmed. By comparing the average size of the SPPs between Cr-containing alloys and Cr-free alloys, it is revealed that the introduction of Cr element could remarkably refine the SPPs. The effects of Cu on the type of SPPs formed in Cr-containing and Cr-free alloys were also found different. In the Cr-containing alloys, in addition to hexagonal and cubic Zr(Fe,Cr,Nb) 2 , Zr 3 Fe SPPs was observed with the introduction of 0.05 wt% Cu. In contrast, Zr 2 Fe SPPs was observed but (Zr,Nb) 2 Fe disappeared in the Cr-free alloys with the introduction of 0.1 wt% Cu. With the adding of suitable amount of Cu, the number of precipitated SPPs significantly increased accompanied by a refinement in SPPs average size. In addition, stacking faults were founded in some Laves phases. [ABSTRACT FROM AUTHOR]

The density of precipitates is the most important factor in the strengthening effects of alloys by aging. We here use first-principles calculation to reveal the mechanism of increasing density of precipitates by adding alloying elements for Mg-Zn alloys. The Guinier-Preston (G.P.) zones, which begin to occur during the early stage of precipitation, play an important role in the strengthening of the Mg-Zn alloys. To reveal the mechanism of formation of G.P. zones in Mg-Zn alloys with different alloying elements, we have undertaken systematic calculations to investigate the influence of Ag, Ca, Zr and Al on the stability of G.P. zones in Mg-Zn alloys. We find that the formation energies of Zn G.P. zones with Ag and Ca are much lower than that of pure Zn G.P. zones, while the formation energies of Zn G.P. zones with Zr and Al are slightly higher than that of pure Zn G.P. zones. It indicates that the effects of Ag and Ca to enhance the stability of G.P. zones are much stronger than these of Zr and Al, which is consistent with the experimental observation that Ag and Ca can promote efficiently the density of precipitation of G.P. zones in Mg-Zn alloys, but Zr and Al cannot. We also find that the combined addition of Ag and Ca not only enhances the stability of G.P. zones but also decreases the difference of formation energies of G.P. zones parallel to different habit planes, which provides conditions for increasing nucleation sites for G.P. zones that corresponds better strengthening effect. Furthermore, we analyze electronic structures to understand the different roles of these alloy elements in alteration of stability of G.P. zones. [ABSTRACT FROM AUTHOR]

First principles calculation is conducted to systematically investigate the effects of alloying elements (Mo, Re, Os, Ta, Ti, and V) on phase stability, stacking fault energy, ductility, and restoring force of W. It is found that the addition of Mo, Re and Os would decrease the generalized stacking fault energy (GSFE) of W and increase the ductility of W, while the alloying elements of Ti, Ta, and V could enhance its GSFE and reduce its ductility. The different effects of alloying elements would be mainly attributed to the intrinsic interaction between W and the alloying element, i.e., the repulsive interaction of W-Mo, W-Re, and W-Os with positive heats of formation would increase the interlayer distance of W and facilitate its slip, whereas the attractive interaction of W-Ti, W-Ta, and W-V with negative heats of formation would reduce the interlayer distance of W and impede the slip. The derived results are in good agreement with available observations in the literature, and could provide a deep understanding of the effects of alloying elements on various properties of W. [ABSTRACT FROM AUTHOR]

The effect of alloying elements, Mn, Ti, and Mo, on the corrosion behavior of FeCoNiCr-based high entropy alloy (HEA) in supercritical water was investigated. The corrosion resistance of the HEA was enhanced by adding Mo while reduced with the addition of Ti and Mn. The segregation of Ti and Mo resulted in the formation of oxide films that were both structurally and chemically heterogeneous. Grain boundaries accelerated the diffusion rate of Mn, leading to the formation of MnCr 2 O 4 oxide scales decorated with Mn 2 O 3 particles. In addition, the governing mechanisms of alloying elements on the corrosion behavior of HEAs were also discussed. • Alloying elements, Mn, Ti, and Mo, on the corrosion behavior of FeCoNiCr-based HEA in SCW was investigated. • Mo enhanced corrosion resistance, while Ti and Mn reduced corrosion resistance. • Complex structure and chemical composition of oxide films were formed due to the segregation of Ti and Mo. • MnCr 2 O 4 oxide scale decorated with Mn 2 O 3 particles was formed due to the accelerated diffusion of Mn along grain boundaries. [ABSTRACT FROM AUTHOR]

Fe-13Cr-2Al-1Si damping alloys with high damping capacity were chosen as the research object in this study. 0.5Cu+0.5Mo and 0.5Ti+0.5Mo replaced 1Si without variation in other component contents. The paper investigated the effect of alloying elements Cu, Mo and Ti on the microstructure, damping capacity and magnetic domain structure of Fe-13Cr-2Al-1Si alloys. The results indicated that the alloy elements Cu, Mo, and Ti had no effect on the phase structure and microstructure of Fe-13Cr-2Al-1Si damping alloys. However, after the replacement of 1Si by 0.5Cu+0.5Mo and 0.5Ti+0.5Mo respectively, “dendritic” magnetic domain structure could be easily observed in the alloys and the alloys could keep high damping behavior in a wider range of strain amplitude. Besides, it is shown that after adding alloy elements, the damping behavior of Fe-13Cr-2Al-1Si alloys was somewhat different from that of traditional ferromagnetic alloys. In high strain amplitude region there was ferromagnetic damping as well as static hysteresis dislocation internal friction, which might affect the alloy damping capacity. [ABSTRACT FROM AUTHOR]

In this research, effect of alloying elements (X = Cu, Co, Ni, Sb and Bi) and growth rates on the microstructure and mechanical properties (microhardness and tensile strength) of the directionally solidified Al–Si eutectic alloy have been investigated. Al–12.6Si–2X (wt. %) samples were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified under constant temperature gradient and different growth rates (8.3–166.0 μm/s) by using a Bridgman–type growth apparatus. Interflake spacings, microhardness and tensile strength were expressed as functions of growth rate. The effects of alloying elements and growth rates on microstructure, microhardness and tensile strength were determined. According to experimental results, the microstructures, microhardness and tensile strength of the solidified Al-Si-X samples changes with alloying elements (Cu, Co, Ni, Sb and Bi) and the growth rates. The results obtained in this work have been compared with the similar experimental research in the literature. [ABSTRACT FROM AUTHOR]

Due to the reliability problem and high melting point, the development of lead-free solders is hindered. Alloying is considered to be a promising approach to design new Sn-based solders. Cu 6 Sn 5 plays an important role in the quality of microelectronic packaging that formed at the interface of solder and Cu substrate. In the present study, first principles calculations were employed to study the occupation properties of alloying elements (A = P, Zn, Ag, In, Sb, Ce, Pb, and Bi) and anti-site defects (Cu and Sn) in (0 1 0) surface of Cu 6 Sn 5 and their influence on the electronic structures of Cu 6 Sn 5 (0 1 0) surface. Formation energies were calculated to evaluate the occupation preferences of alloying elements in considered eight sites of Cu 6 Sn 5 (0 1 0) surface. Different alloying elements show different occupation preferences. The occupations of alloying elements in Cu 6 Sn 5 surface show negative formation energies comparing the positive formation energies in bulk Sn. Therefore, the alloying elements will easily occur in the Cu 6 Sn 5 compound during soldering process. Electronic structures were studied to reveal the occupation mechanisms of alloying elements, and the interactions between them and Cu 6 Sn 5 surface. Large values of density of states appear around the Fermi energy level for Ce contained system. In terms of the lowest work function, the electrons in Ce contained systems will be much easier to lose than that in other contained systems. Therefore, alloying of Ce will greatly affect the stability and electrical properties of solder joints in microelectronic packaging. [ABSTRACT FROM AUTHOR]

The effect of alloying elements on the formation of long cylindrical pores was investigated for lotus-type porous Cu. The lotus-type porous Cu was fabricated using the centrifugal casting technique under hydrogen atmosphere with the addition of Ni, Co, Mn, Si, Sn, or P. The porosity and average pore diameter were significantly affected by the addition of alloying elements. The porosity was independent of the addition of Ni or Co but decreased with increasing Mn, Si, Sn, or P content. The average pore diameter exhibited minimum at 0.05 at.% Ni content and 0.02 at.% Co, Mn, or Si. It then increased as the content of alloying elements was increased up to 0.1 at.%. The average pore diameter sharply increased with increasing Sn or P content up to 0.1 at.%. It is suggested that the addition of alloying elements is an effective way to control the porosity and average pore diameter in lotus-type porous Cu without additional change of processing parameters such as the hydrogen gas pressure and solidification velocity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The microbial corrosion resistance of 09CrCuSb LAS is better than that of Q235 CS. • The alloying elements in 09CrCuSb LAS inhibit the sessile bacterial growth. • Fewer sessile bacteria on the 09CrCuSb LAS surface lead to a lower EET rate. • The alloying elements in 09CrCuSb LAS have a combined effect on inhibiting MIC. The microbial corrosion of marine structural steels (09CrCuSb low alloy steel (LAS) and Q235 carbon steel (CS)) in Desulfovibrio vulgaris medium and Pseudomonas aeruginosa medium based on seawater was investigated. In the D. vulgaris medium, the weight loss and maximum pit depth of 09CrCuSb LAS were 0.59 and 0.56 times as much as those of Q235 CS, respectively. Meanwhile, in the P. aeruginosa medium, the values were 0.53 and 0.67 times, respectively. Compared to Q235 CS, 09CrCuSb LAS contains more alloy elements (Cr, Ni, Cu, Al and Sb), which led to obvious inhibition of sessile bacteria growth but had no effect on planktonic bacteria. The number of live sessile cells on the 09CrCuSb LAS surface was 23.4 % and 26.9 % of that on the Q235 CS surface in the D. vulgaris medium and P. aeruginosa medium, respectively. Fewer sessile cells on the steel surface led to a lower extracellular electron transfer (EET) rate so that less corrosion occurred. In addition, the combined effect of alloying elements on grain refinement and passive film formation also improved the anti-corrosion property of the steels. [ABSTRACT FROM AUTHOR]

This work reports atomic-scale experimental and modeling studies of the zirconium oxide microstructure formed at the metal-oxide (M/O) interface, and the crystallography as well as the redox chemistry of alloying element nickel in the corrosion layer found on a serviced boiling water reactor Zircaloy-2 fuel rod cladding. Complying with radioprotection aspects a small-sized sample with only limited radioactivity, taken from a very high burnup (∼ 79 MWd/kgU) cladding tube material, was prepared for the investigation using synchrotron-based X-ray microprobe techniques such as X-ray fluorescence (μXRF), X-ray diffraction (μXRD) and X-ray absorption spectroscopy (μXAS). The patterns of Ni K-edge XAS of solute Ni, probed at several location within the corrosion layer, have been recorded and analyzed. Close to the metal-oxide interface both the allotropic forms of zirconium oxide, monoclinic and tetragonal phases, have been identified by XRD analyses. XAS results of the barrier layer at the metal-oxide interface reveal that the oxides contain Ni atoms as divalent cations located in the proximity of oxygen vacancies. Near the M/O interface regions, all oxidized nickel atoms have a Ni2+ homogeneous distribution and no trace or even evidence of any metallic Ni is found in the oxide matrix. The experimental results, also supported by first-principles ligand field DFT calculations, are interpreted in term of energetics, stability, chemical and structural specificity of divalent Ni ions in zirconium oxide microstructure. The present investigation on the basis of a combined experimental and theoretical approach shows that the oxidized nickel ions being situated in the neighborhood of oxygen defects is influential on the hydrogen evolution reaction including the hydrogen intake behavior accompanied with the oxidation reaction in irradiated Zircaloy-2. • This work reports an atomic-scale study of the redox chemistry of nickel in the corrosion layer formed on a Zircaloy-2 cladding. • The chemical state and Ni speciation in the oxide layer have been obtained by synchrotron X-ray light experiments. • Near the metal/oxide interface regions, all oxidized nickel atoms have a bivalent ion distribution adjacent to oxygen vacancies. • There is no trace or even evidence of any metallic Ni found in the oxide matrix. • The results of this study have strong implications for understanding the hydrogen intake behavior in irradiated Zircaloy-2. [ABSTRACT FROM AUTHOR]

The roles of the alloying elements, Ti and Ta, on the γ' strengthening phase and the corresponding high temperature deformation responses of the CoNi-based superalloys have been systematically investigated. The results indicate that addition of either 4 at.% Ti (4Ti) or 2 at.% Ta (2Ta) can significantly increase the volume fraction of the γ' phase. Detailed analysis of the deformation mechanisms and Gibbs free energies of each phase in the two alloys at elevated temperatures were carried out by using the transmission electron microscopy (TEM) characterization and the thermodynamic calculation, respectively. The dislocations shearing into the γ' precipitates is the primary deformation mechanism in both alloys when deformed at 600 °C. However, when increasing the deformation temperature to 800 °C, the dislocation cross-slipping and by-passing mechanism dominants the 4Ti alloy's deformation, while the additional stacking faults (SFs) were introduced to the 2Ta alloy due to the lower barrier energy of the SFs formation. Continuing increasing the deformation temperature to 1000 °C will promote the dislocation-based mechanisms by lower the dislocation propagation resistance in both alloys. The process will also induce the mechanical twins in the 2Ta alloy which can further strengthening the alloy. The alloying induced deformation mechanism transition and the related high-temperature mechanical performance of the CoNi-based superalloys have been further discussed. • Adding Ti or Ta to the CoNi-based alloy will improve its γ' volume fraction to 60% • Ti and Ta will improve the flow strength at medium and high temperature, respectively • Ta can reduce the energy barrier for stacking fault formation at high temperature • Deformation mechanisms at elevated temperatures can be altered by the alloy elements [ABSTRACT FROM AUTHOR]

The isothermal oxidation behavior of high-Nb-containing TiAl alloys doped with W, B, Y, and C (WBYC) /Si (WBYS) was investigated via oxidation tests at 900 °C in ambient air. Both alloys exhibited outstanding high-temperature oxidation resistance, with unit weight gains of < 1 mg/cm2 after 200 h of oxidation at 900 °C. The inclusion of alloying elements could refine the crystalline particle size and reduce oxygen activity, consequently suppressing TiO 2 growth and promoting Al 2 O 3 formation. Furthermore, the generated oxide pegs improved the adhesive strength between the oxide scale and the substrate and the spalling resistance of the oxide scale. • The oxidation resistance of Ti45Al8Nb alloys was effectively improved by the addition of W, B, Y, and C/Si. • The oxidation-induced mass gain values of both alloys are less than 1 mg/cm2 after oxidation at 900 °C for 200 h. • Compared with C doping, the addition of Si effectively improves the oxidation resistance of TiAl alloy. [ABSTRACT FROM AUTHOR]

MCrAlX coatings (M = Ni, Co or NiCo; X = Y, Hf, Ta and Si, etc.) have an excellent oxidation resistant, but in which the various alloying elements will lead to the difference in evolution mechanism of microstructure at high temperature, and thus affects its friction and wear mechanism. Therefore, NiCrAlY, NiCoCrAlYHfSi and NiCoCrAlYTa coatings are deposited by high velocity oxy-fuel (HVOF) spraying technology in this work. The tribological properties of three kinds coatings at 800 °C are mainly investigated. The emphasis is placed at the influences of alloying elements on evolution mechanism of microstructure as well as mechanical and tribological properties of three coatings. All the coatings are dense and uniform, and their phases are roughly same. However, the different alloying elements lead to the different mechanical properties of coatings. Meanwhile, with the increase of hardness, the wear rate and friction coefficient of the coatings decrease obviously. Especially, the friction coefficient and wear rate of NiCoCrAlYTa coating are significantly lower than those of the other coatings. This phenomenon is mainly attributed to the transformation of worn damage pattern of the coating and the generation of continuous glaze layer at the friction interface. In conclusion, this work could be considered as a guidance to expand the applications of MCrAlX-based coating in modern industries. [Display omitted] • The performance of MCrAlX-based coatings is different with varying alloy elements. • The NiCoCrAlYTa coating exhibits the better mechanical and tribological properties. • The wear mechanism of coatings is related to the formation and spreading of glaze layer. • The glaze layer is composed of mixed oxides, layer-like spinel and amorphous phase. [ABSTRACT FROM AUTHOR]

This study investigates the damping properties of Cu–Al–Mn shape memory alloys (SMAs) with various chemical compositions and the effects of the addition of quaternary alloying elements Ag and Nb on the microstructure, martensitic transformation behavior, and damping capacity of SMAs. Compared to other Cu–12Al– x Mn (x = 4–7 wt%) SMAs, Cu–12Al–5Mn has a more significant inherent and intrinsic internal friction (IF PT + IF I) peak above room temperature. The addition of Ag or Nb to Cu–12Al–5Mn reduced the grain size, thereby increasing the hardness of the alloys; however, the damping capacity and temperature of the IF PT + IF I peak decreased simultaneously. The addition of Ag to Cu–12Al–5Mn significantly reduced the damping capacity (IF PT +IF I peak) because of the notable decrease in the amount of transformed martensite. Moreover, the addition of Nb to Cu–12Al–5Mn caused the AlNb 3 phase to precipitate, limiting the mobility of the martensite variant interfaces and slightly decreasing the damping capacity (IF PT + IF I peak). Among the Ag- and Nb-doped Cu–12Al–5Mn SMAs, Cu–12Al–5Mn–1 Nb showed not only a significantly higher hardness but also a higher IF PT + IF I peak, with tan δ exceeding 0.01 at approximately 50 °C. [Display omitted] • In Cu-based SMAs, damping capacity depends on microstructure and the volume fraction of the transformed martensite. • Alloying elements with different mechanisms affect the damping performance of Cu-based SMAs. • In Cu-based SMAs, both damping capacity and mechanical strength improve by optimizing chemical composition. [ABSTRACT FROM AUTHOR]

[Display omitted] • TiB whiskers in TA2 are needle-like, those in TB2 are short-flaky and thick-acicular. • Alloying elements of V, Mo, Al and Cr have higher solubility in β-Ti but less in TiB. • The strong chemical bonds are formed at TiB/β-Ti interface. • The theory model of boride layer growth in Ti alloys contains three main stages. As one of the important ways to improve surface properties of Ti alloys, the boride layer prepared by the pack boriding is closely related to the growth and morphology of TiB whiskers in the boride layer, whereas the growth and morphology of TiB whiskers are significantly affected by alloying elements in the alloys. This work systematically explored the effect of alloying elements in β-type Ti-5Mo-5V-8Cr-3Al Ti alloy on growth kinetics of TiB whiskers and thickness of the boride layer using experiment and first-principles investigations. After boriding, an outer TiB 2 layer and an inner TiB whisker + Ti layer are formed on Ti surface. TiB/β-Ti interface herein is non-coherent with the orientation relationships of (0 1 1) TiB //( 1 ¯ 1 ¯ 0) β-Ti and [ 1 ¯ 00] TiB //[ 1 ¯ 11] β-Ti. Alloying elements segregated at the interface can increase diffusion energy barrier and slow down diffusion rate of active [B] atoms, and further reduce growth rate of TiB whiskers. Finally, a theoretical model for the boride layer growth on Ti surface was proposed. [ABSTRACT FROM AUTHOR]

The corrosion of weld metals with Cr, Ni, Cu or Mo in gas field produced water with saturated CO 2 and H 2 S was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), optical profiler, and electrochemical tests. The addition of alloying elements led to a decrease in polygonal ferrite and pearlite, whereas an increase in acicular ferrite in weld metal. Morphological and compositional analysis manifested that corrosion scale on weld metals primarily consisted of FeCO 3 and iron sulfides, and Cr(OH) 3 also existed on Cr-containing weld metals. With increased alloying elements, especially chromium, localized corrosion resistance was improved. This improvement was ascribed to the presence of alloying elements in substrate and Cr-rich products in scale, which can inhibit the oxidation of iron sulfides, thereby improving the structure of corrosion scale. Electrochemical tests showed that the anodic dissolution reaction of weld metal with higher Cr, Ni, Cu or Mo was inhibited in more extent, and the increase in total reaction impedance depended on weld metal surface active state. The preliminary corrosion mechanism of weld metal in CO 2 /H 2 S environment was proposed. • Corrosion behavior of weld metals with Cr, Ni, Cu and Mo in CO 2 /H 2 S environment is studied. • Iron oxides formed by the oxidation of iron sulfides make corrosion scale looser. • The addition of alloying elements can inhibit the oxidation of iron sulfides. [ABSTRACT FROM AUTHOR]

The influence of alloying elements on the sintering behaviors of Cu is investigated by using Cu green samples doped with 0.5 wt% of Cr, Ti, Al, Mo, Nb and W. The sintering of Cu is greatly promoted by adding Cr, Ti and Al, but impeded by adding Mo, Nb and W. Among all alloying elements, Cr shows the most significant promoting effect, with the relative density of the Cu-0.5 wt% Cr sample being increased to 95% after sintering, about 5% higher than the pure Cu sample. Both the thermodynamic analysis and microstructure observation of the sintered samples suggest that the sintering enhancement can be attributed to the reduction of oxide layer on the Cu powder. The sintering-promoting elements are more affinitive to oxygen. Therefore, they are more likely to react with the oxide layer on the powder surface and facilitate the sintering. [ABSTRACT FROM AUTHOR]

An Inductively Coupled Plasma Optical Emission Spectrometry method for simultaneous determination of Al, Ca, Cu, Fe, In, Mn, Ni, Si, Sr, Y, Zn, Zr and rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in magnesium alloys, including the new rare earth elements-alloyed magnesium, has been developed. Robust conditions have been established as nebulizer argon flow rate of 0.5 mL min −1 and RF incident power of 1500 W, in which matrix effects were significantly reduced around 10%. Three acid digestion procedures were performed at 110 °C in closed PFA vessels heated in an oven, in closed TFM vessels heated in a microwave furnace, and in open polypropylene tubes with reflux caps heated in a graphite block. The three digestion procedures are suitable to put into solution the magnesium alloys samples. From the most sensitive lines, one analytical line with lack or low spectral interferences has been selected for each element. Mg, Rh and Sc have been studied as internal standards. Among them, Rh was selected as the best one by using Rh I 343.488 nm and Rh II 249.078 nm lines as a function of the analytical lines. The trueness and precision have been established by using the Certified Reference Material BCS 316, as well as by means of recovery studies. Quantification limits were between 0.1 and 9 mg kg −1 for Lu and Pr, respectively, in a 2 g L −1 magnesium matrix solution. The method developed has been applied to the commercial alloys AM60, AZ80, ZK30, AJ62, WE54 and AE44. [ABSTRACT FROM AUTHOR]

First-principle calculation was performed to illustrate the atomic arrangement and segregation behavior of Sn/Ti and O in Σ 3 [ 1 1 ¯ 0 ] ( 111 ) grain boundary, and the interaction of oxygen interstitials with Sn/Ti atoms on the grain boundary was studied. The analyses on the segregation energies and geometric positions, and the electron densities show that Sn, Ti and O atoms segregate at the Σ 3 grain boundary. And the preferred segregation sites of the impurities at Σ 3 [ 1 1 ¯ 0 ] ( 111 ) were determined. When Sn segregates at grain boundary plane, the O atom prefers to the bulk-like site and shows no segregation tendency at grain boundary, whereas the segregated Ti atom can slightly enhance oxygen segregation at the grain boundary. [ABSTRACT FROM AUTHOR]

First principles calculations are performed to study the influence of alloying elements Li, Na, K, Ti, Mn, and Ni and Y vacancy on the stability and dehydrogenation properties of Y(BH 4 ) 3 . The formation energies of low and high temperature (LT and HT) phases of alloyed Y(BH 4 ) 3 are evaluated. Ti, Mn, and Ni elements and the Y vacancy containing Y(BH 4 ) 3 systems are endothermic. The Y vacancy is difficult to be generated due to the high energy demand. The alkali metals of Li, Na, and K prefer to occupy the interstitial sites in both the LT and HT phases of Y(BH 4 ) 3 , especially the K element. The K containing systems show negative formation energy, even if eight K atoms are introduced. The K containing systems show similar structure characteristics with the KY(BH 4 ) 4 compound. Therefore, a phase transition from the K alloyed Y(BH 4 ) 3 to KY(BH 4 ) 4 is expectable. However, the transition from Li/Na alloyed Y(BH 4 ) 3 to corresponding Li/Na–Y(BH 4 ) 4 compounds is energetically unfavorable. Electronic structures of alloyed Y(BH 4 ) 3 are investigated to explore the reasons that why only K alloyed Y(BH 4 ) 3 can transform to KY(BH 4 ) 4 compound. In term of dehydrogenation properties, all alloyed systems show smaller dehydrogenation energies than the pure Y(BH 4 ) 3 . The concentrations of alloying elements can greatly affect the dehydrogenation properties of alloyed Y(BH 4 ) 3 . [ABSTRACT FROM AUTHOR]

Warm deformation behaviors of high-Mn TRIP steels with martensitic structure were investigated using a Gleeble 1500 hot simulator within the temperature range of 550-650 °C and the strain rate range of 0.001-0.1 s-1. The influences of common alloying elements, i.e. C, Mn, Si and Al, on the flow stress and the microstructural evolution during warm deformation were analyzed. The results showed that the flow stress was increased with the increase in C content, Mn content, Si content or Al content at the same condition, and the deformation activation energy Q was increased with the increase in Mn content and decreased by the increase in C content. The increase in Si content or Al content showed slight influence on the deformation activation energy Q. During warm deformation the decomposition of martensite into ferrite and carbides occurred firstly, and then dynamic recrystallization (DRX) of ferrite and the reverse transformation of austenite took place. DRX of ferrite was retarded by the increase in Mn content or Si content and accelerated by the increase in C content. Meanwhile, the reverse transformation of austenite was promoted by the increase in Mn content and retarded by the increase in C content, Si content or Al content. [ABSTRACT FROM AUTHOR]

A Machine Learning (ML) integrated process was utilized to optimize the properties of Sn–Ag–Cu (SAC) alloys. Bi and In were selected as the key alloying elements to optimize the mechanical properties of SAC387 based alloys. A virtual sample space was constructed for SAC387-xBi-yIn alloys using a machine learning model based on Gradient Boosting Decision Tree (GBDT) algorism. A series of virtual samples were selected and experimentally validated. Sample SAC387-3.5 wt%Bi-2.8 wt%In demonstrated an outstanding mechanical property, yielding a significant improvement in tensile strength (85.8% improvement vs. SAC387, 106% improvement vs. SAC305) with an acceptable ductility (>20%). The synergistic effects of co-additions of Bi and In on the properties of SAC387 based alloys were elucidated. The experimental results show good consistency with the ML predictions, proving that ML can be used as a powerful tool for designing lead-free solder alloys with optimized properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Si aggravates liquid metal embrittlement sensitivity of advanced high strength Q&P steels. • Si influences the susceptibility to liquid metal embrittlement more strongly than C, Mn, or Al. • Si slows down Fe-Zn intermetallic formation and promotes a "direct" contact between liquid Zn and the steel substrate. • The Si effect on retarded Fe-Zn alloying is consistent with the phase equilibria of the Fe-Zn-Si ternary system. In this work, the influence of selected alloying variations on Zn-assisted liquid metal embrittlement (LME) susceptibility of Zn-coated advanced high strength steels (AHSS) is investigated. Cold-rolled AHSS alloys of different carbon (C), manganese (Mn), silicon (Si), and aluminum (Al) concentrations were continuous-annealed to generate a third generation AHSS microstructure (composed of martensite and retained austenite) via quenching and partitioning. High temperature tension tests using simulated spot-weld thermomechanical cycles revealed no significant influence of C and Mn variations on the Zn-LME susceptibility of AHSS. On the other hand, Zn-LME susceptibility was strongly correlated with the Si content of AHSS. A direct comparison of the (reacted) coating microstructures of the Si-alloyed and Low-Si AHSS variants revealed that Si in the AHSS substrate suppresses Fe–Zn alloying reactions and retards the nucleation and growth of Fe-Zn intermetallic phases at the coating-substrate interface in these spot weld simulations. The suppressed intermetallic formation at elevated Si concentrations is consistent with phase equilibria considerations in the Fe-Zn-Si ternary system. In the context of Zn-assisted LME, therefore, Si is hypothesized to aggravate LME behavior by increasing the liquid Zn availability for embrittlement and promoting direct contact between liquid Zn and the AHSS steel substrate. [ABSTRACT FROM AUTHOR]

Investigations about how to improve the properties of high entropy alloys (HEAs) play a key role in growing their potential for use in future industrial applications. Accordingly, this study aims to shed light on the effects of alloying elements (Si, Cu and Si-Cu co-added) on the microstructure and oxidation performance of the Fe 2 CoCrNi 0.5 based high entropy alloys. To this end, a series of high entropy alloys containing Fe 2 CoCrNi 0.5 , Fe 2 CoCrNi 0.5 Si 0.25 , Fe 2 CoCrNi 0.5 Cu 0.25 and Fe 2 CoCrNi 0.5 Si 0.25 Cu 0.25 were produced by electric current assisted sintering (ECAS) method, which is founded on the principle of simultaneous application of high-density electric current flowing through the powder mixture and uniaxial pressure within a short span of time. The oxidation test was carried out in air at 1123 K for 1200 h under cyclic conditions. The X-ray diffraction results showed that all HEAs have simple FCC solid solution phases. Among all HEAs, the oxidation resistance of the alloy exhibited an increasing trend with the Si addition and the best oxidation behavior at 1123 K for 1200 h was noted with Fe 2 CoCrNi 0.5 Si 0.25 , which experienced the least mass change of 4.72 mg cm−2. Cu addition caused the highest mass change of 15.92 mg cm−2 and the thickest oxide scale of 38.2 µm after oxidation for 1200 h. Si addition is observed to enhance the amount of Cr-rich oxide in the scale. The oxide scale formed on HEA with Cu-added and HEA with Si-Cu co-added contained two oxide layers, including an outer layer of Fe-rich oxide and an inner layer of Cr-rich oxide, which showed continuous structure. However, the alloying elements did not play a favorable role in relieving the formation of internal oxidation. Additionally, it has been reported that Fe 2 CoCrNi 0.5 Si 0.25 HEA can exhibit high resistance to cyclic oxidation, which can be reasoned as an optimum material for structural and high-temperature applications. • Alloying element behavior has been shown to have a significant influence on the investigated properties of HEAs. • Si has proved to be effective in enhancing oxidation resistance. • Cu addition produced the thickest oxide scale. • One of the encouraging results of this investigation was the synergic effect of Si-Cu co-added. [ABSTRACT FROM AUTHOR]

The effects of alloying elements (Mg, Zn, Cu, Sc and Ti) on the interfacial bonding between a carbon nanotube (CNT) and an Al(111) surface are studied systematically using first-principles total energy calculations. The redistribution of the charge density of the Al(111) surfaces induced by the five alloying elements, the projected densities of state, and the crystal orbital Hamilton population analysis of the atomic pairs in the vicinity of the interface are analyzed in detail. Thereby, it is revealed that the bonding characteristic between the CNT and the Al(111) surfaces are modified when alloying with the early transition metals Sc and Ti that occupy subsurface positions. Also for the other alloying elements a weak interaction between CNT and the substrates is found although these elements occupy surface positions in the Al(111) surface. Through a detailed study of the interaction potential energy and the restructuring energy, we demonstrate that different mechanisms are responsible for the substrate–CNT interactions. [ABSTRACT FROM AUTHOR]

In the article the possibility for increasing the fire resistance of structural steel used in building load-bearing structures is presented and discussed in detail. The recommended approach is based on a suitable modification of its chemical composition, in particular by adding the carefully selected alloying elements. With such a change, not only a high-temperature strength of this material may be significantly increased in relation to that which would be achieved for the typical structural steel with an unmodified composition but also its sufficient weldability should be ensured by the entire duration of its exposure to a fire. The steel modified in this way would be undoubtedly more expensive to manufacture but due to the fact that it will not require any special protection against fire it seems that it can provide an interesting alternative to the solutions currently used in engineering practice. [ABSTRACT FROM AUTHOR]

The effects of Co and Co + Al addition on the microstructure, deformation-induced processes, and mechanical properties of a wrought Fe–14Cr–9Ni–3Mn–0.3C austenitic stainless steel were investigated. Whereas Al contributes to a reduced density and has a noticeable impact on the microstructure formation, Co addition could be regarded as a strategy to replace Ni, for instance to avoid Ni allergy. During tensile deformation at 300 °C, dynamic strain aging occurred in all steels but the associated increase in the work hardening rate was most obvious for the steel containing Co + Al. As the tensile test temperature was decreased to −196 °C, the yield strength of all steels increased. Furthermore, planar glide features such as deformation-induced α′-martensitic transformation became more dominant. Co and Co + Al additions reduced the M d γ→5%α′ temperature and the amount of deformation-induced α′-martensite. The extent to which deformation-induced α′-martensite formation was suppressed was much greater upon Co + Al addition than upon Co addition alone. Accordingly, the work hardening rate at a given tensile test temperature was highest for the reference steel and lowest for the Co + Al-added steel with the most stable austenite of all steels. The highest tensile elongation of steels was reached at temperatures below their respective M d γ→5%α′ temperature. For the reference steel, the interval between the temperature associated with maximum elongation and M d γ→5%α′ temperature was the smallest. For the other two steels, in particular the one containing both Co and Al, the preceding interval was noticeable. This observation is likely related to the non-uniform spatial distribution of alloying elements and local variations in deformation mechanisms. • Al causes significant lattice expansion of austenite, Co decreases it slightly. • Co and Al, in particular Al, increase the mechanical stability of austenite. • Both Co and Al reduce M d γ.→5%α′ and oppose DIMT, with Al being more effective • Co and Al promote dynamic strain aging, though the effect of Al is more pronounced. • Tensile elongation of Co and CoAl steels reaches a maximum below M d γ.→5%α′ [ABSTRACT FROM AUTHOR]

The electrochemical and hot corrosion behaviors of Fe 2 CoCrNi 0.5 based HEAs were investigated. The HEA with the best electrochemical corrosion resistance was Fe 2 CoCrNi 0.5 Si 0.25 Cu 0.25 with E corr of − 0.584 V, I corr of 1.47 × 10–4 A/cm2. Fe 2 CoCrNi 0.5 Cu 0.25 had the worst resistance to hot corrosion, as caused by the more severe attack and poor adherence of scale. However, Si addition contributed to better corrosion resistance.The positive effect of Si is thought to be associated with rendering the formation of a relatively denser and more adherent scale that could behave as a barrier to the penetration of oxygen and molten salt towards the substrate. • A study to improve corrosion performance of the high entropy alloys is presented. • Enhanced hot corrosion resistance was achieved by adding Si. • Cu addition presented a corrosion scale that was cracked, porous, and non-protective. • The alloying process could be a promising direction in designing corrosion-resistant HEAs. [ABSTRACT FROM AUTHOR]

The influence of refractory additions on tensile deformation behavior has been studied at an intermediate temperature (760°C) using scanning and transmission electron microscopy. Tensile experiments revealed that elemental additions of tantalum (Ta), tungsten (W), and rhenium (Re) could improve the yield strength (YS) of the model alloys with an order of YS(Ni–Al–W) > YS(Ni–Al–Ta) > YS(Ni–Al-Re) > YS(Ni–Al). During the plastic deformation of model alloys at the intermediate temperature, the deformation via Orowan bypassing and shear could be activated synergistically. The changes of anti-phase boundary (APB) energies on {001} and {111} planes are related to the cross-slip driving force, critical resolved shear stress and stage II work hardening rate in γ' precipitates. The effects of γ' size and refractory additions (Ta, W, and Re) on the yield strength of model alloys at intermediate temperature are also discussed, which can provide qualitative reference for alloy design. • The effect of Re on the yield strength and plasticity is less than that of Ta and W. • The lattice distortion related with changes in APB energies and order strengthening. • There is a positive correlation between cross-slip driving force and stage II WHR. • At medium temperature, Orowan bypassing and γ' shearing are activated synergistically. • W and Ta are two promising candidates for replacing precious Re element. [ABSTRACT FROM AUTHOR]

NiAlY alloys with the addition of Zr, Ti, Ta and Mo were prepared by arc melting. The oxidation and NaCl-induced hot corrosion behavior of the alloys were investigated at 650 ℃, with the focus on the effect of element-doping and phase. With the addition of Ti, Ta and Mo, the oxidation resistance of the tested alloys was effectively enhanced compared to the undoped NiAlY alloy. However, the NiZrAlY alloy showed very poor oxidation resistance. Under the NaCl-induced hot corrosion test, the NiTaAlY and NiMoAlY alloys exhibited an improved hot corrosion resistance, while the NiZrAlY and NiTiAlY alloys showed very poor hot corrosion resistance. Moreover, the NiAl and Ni 5 Y phases exhibited different behavior during the oxidation and NaCl-induced hot corrosion tests. • A new type NiXAlY system doped with different alloying elements was designed in this work. • The oxidation and hot corrosion behaviors of NiAlY alloys with different alloying elements addition such as Zr, Ti, Ta and Mo were investigated at 650 ℃. The effects of different alloying elements on oxidation and hot corrosion resistance were investigated. • Y displayed a negative effect in both oxidation and hot corrosion resistance. The degradation mechanisms of Y-rich areas in the oxidation and hot corrosion tests were different. [ABSTRACT FROM AUTHOR]

• Cr/Mo/W dopant changes the occupying priority of interstitial He in pure Ni. • NiCr has a relatively higher migration barrier than pure Ni, while both NiMo and NiW are lower. • Effective diffusivity of interstitial He atom in Ni-based alloys decreases with increasing of the temperature and Cr/Mo/W concentrations. • Cr/Mo/W alloying influences He clustering properties and hampers their growth to larger sizes, in addition to Cr trapping smaller clusters. In nuclear reactors, the helium (He) production and retention from intensity particle irradiation can degrade the physical and mechanical properties of Ni-based alloys. Understanding the fundamental behaviors of He in metals is a critical issue in the development of nuclear materials. In this research, the influence of Cr/Mo/W additions on the stability, migration, and clustering of He in face-centered cubic (fcc) nickel were systematically studied by using density functional theory (DFT). The formation and binding energies show that Cr and Mo/W atoms affect the occupying priority of tetrahedral interstitial He in Ni lattice. The interstitial He prefers to occupy the first nearest neighbor octahedral site with the presence of Cr, while it would locate far away from Mo/W addition. For He migration around alloying elements, the barrier of interstitial He in NiCr is slightly higher than that of pure Ni, while NiMo and NiW systems have a relatively lower barrier. The effective diffusivity of interstitial He atom in Ni-based alloys significantly decreases with the increase of the temperature and Cr/Mo/W concentration. Moreover, when He aggregates at vacancy, the Cr/Mo/W can weaken the formation energy of He clusters and hamper their growth to larger sizes. All these results provide microscopic insights into Cr/Mo/W alloying effect on helium behaviors in Ni-based materials. [Display omitted] Alloy elements Cr/Mo/W change the diffusion and retention of interstitial He atom in pure Ni. [ABSTRACT FROM AUTHOR]

• The influence of solute elements Ni, Sn and P on the interfacial adhesion properties of γ-Fe (1 0 0)/Cu (1 1 0) interface were calculated by first principle simulation. • The influence of solute elements Ni, Sn and P on the interfacial electronic properties of γ-Fe/Cu interface were calculated by first principle method. • The improvement of mechanical properties attributing to Fe-P covalent bonds and Fe-Ni metal bonds at the interface when the P and Ni atoms doped at γ-Fe/Cu interface. The alloying elements play an important role in the strengthening of lead tin bronze alloy and steel. Similarly, the same is true in γ-Fe (1 1 0)/Cu (1 1 0) interface. In this investigation, the effect of Ni, Sn, and P alloying atoms on the adhesion electronic properties of γ-Fe (1 1 0)/Cu (1 1 0) heterogeneous interface were simulated by using first principle method. The bonding ability of γ-Fe (1 1 0)/Cu (1 1 0) doped interface and their influence on adhesion electronic properties of the interfaces was analyzed, it is found that Ni and P atoms ware apt to doped at the interface Cu slab in the γ-Fe (1 1 0)/Cu (1 1 0)-HCP interface, and the difficulty of atomic doping from easy to difficult was ranked as: P > Ni. However, the doping of Sn atoms was not conducive to the stability and bonding of γ-Fe (1 1 0)/Cu (1 1 0) - BT interface. Besides, The P atom and Ni atom doped interface shows covalent and metallic bond characteristic respectively, which improved the stability and adhesion of the interface. However, Sn atom doped interface hardly transfer the interfacial charge, which lead to the decrease of the bonding performance and the stability of interface. [ABSTRACT FROM AUTHOR]

The Ni atom is difficult to occupy the Ti or Al site in TiAl, it exists in the form of NiTi phase at the grain boundary of TiAl alloy, which is detrimental to the ductility of the TiAl alloy. The Fe and Co atoms preferentially occupy the Al sites and can improve the electronic structures and elastic properties of TiAl, leading to the improvement of the ductility of TiAl alloy. With the addition of 3 at.% Fe and Co, the tested average fracture strain of TiAl alloy increases from 17.3% to 19.1% and 18.0%, respectively. [ABSTRACT FROM AUTHOR]

The corrosion properties of four Mg–5Al alloys with M-alloying elements (tin, manganese and zinc) in a 3.5 wt.% NaCl solution were examined using electrochemical tests and surface analyses. The electrochemical results indicated that the addition of 1 wt.% M metal decreased the corrosion rate and hydrogen evolution rate of the Mg–5Al specimens. Moreover, the addition of 1Zn resulted in having the best corrosion resistance due to the interaction of Zn oxide with Mg and Al oxides which acted as a corrosion barrier. [ABSTRACT FROM AUTHOR]