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Zero thermal expansion (ZTE) alloys with high mechanical response are crucial for their practical usage. Yet, unifying the ZTE behavior and mechanical response in one material is a grand obstacle, especially in multicomponent ZTE alloys. Herein, we report a near isotropic zero thermal expansion (αl = 1.10 × 10−6 K−1, 260–310 K) in the natural heterogeneous LaFe54Co3.5Si3.35 alloy, which exhibits a super-high toughness of 277.8 ± 14.7 J cm−3. Chemical partition, in the dual-phase structure, assumes the role of not only modulating thermal expansion through magnetic interaction but also enhancing mechanical properties via interface bonding. The comprehensive analysis reveals that the hierarchically synergistic enhancement among lattice, phase interface, and heterogeneous structure is significant for strong toughness. Our findings pave the way to tailor thermal expansion and obtain prominent mechanical properties in multicomponent alloys, which is essential to ultra-stable functional materials. Zero thermal expansion materials play an increasingly important role in modern high-precision applications, but they are relatively scarce. Here, the authors achieve an isotropic zero thermal expansion with a very high toughness by manipulating chemical partitioning in chemically complex alloys. [ABSTRACT FROM AUTHOR]

It is well demonstrated that the complex chemical fluctuations on high/medium-entropy alloys (H/MEAs) play critical roles in their deformation process, but there are few reports related to the effect of such complex chemical fluctuations on the crack behavior. In this paper, the effects of chemical short-range order (CSRO) and lattice distortion (LD) on the crack-tip behavior of CrCoNi MEAs under mode I loading at room temperature are investigated by carrying out molecular dynamics (MD) simulation, hybrid MD/Monte-Carlo (MC) simulation and the J-integral method. The results reveal that CSRO can improve the J-integral value without significant changes in the localized deformation zone size. On the contrary, LD can lower the J-integral value with an increase in the localized deformation zone size. The energetic analysis shows that CSRO improves the activation energy barrier of Shockley partial dislocation from the crack-tip while LD reduces the activation energy barrier. Our work is a step forward in understanding the effects of CSRO and LD on the crack-tip behavior and deformation mechanisms of CrCoNi MEAs. [ABSTRACT FROM AUTHOR]

The defining feature of high-entropy alloys (HEAs) is their unprecedented degree of compositional inhomogeneity which influences their dislocation movements. We demonstrate differences between a HEA (Fe40Mn40Co10Cr10) and a conventional solution alloy (316L stainless steel) using acoustic emission (AE) spectroscopy. AE measurements under tension show the coexistence of two avalanche processes in Fe40Mn40Co10Cr10 HEA, whereby one avalanche process relates to the movement of dislocations and the other to detwinning/twinning processes. These two avalanche processes exhibit two branches of the E ∼ A2 correlation. The dislocation movements in Fe40Mn40Co10Cr10 HEA show systematically longer durations compared with the equivalent dislocation movements in the 316L stainless steel and a bias toward faster waiting times for subsequent dislocation movements. The aftershock rate, as identified by the Omori law, is the same for the two materials. [ABSTRACT FROM AUTHOR]

High-performance refractory alloys with ultrahigh strength and ductility are in demand for a wide range of critical applications, such as plasma-facing components. However, it remains challenging to increase the strength of these alloys without seriously compromising their tensile ductility. Here, we put forward a strategy to "defeat" this trade-off in tungsten refractory high-entropy alloys by stepwise controllable coherent nanoprecipitations (SCCPs). The coherent interfaces of SCCPs facilitate the dislocation transmission and relieve the stress concentrations that can lead to premature crack initiation. As a consequence, our alloy displays an ultrahigh strength of 2.15 GPa with a tensile ductility of 15% at ambient temperature, with a high yield strength of 1.05 GPa at 800 °C. The SCCPs design concept may afford a means to develop a wide range of ultrahigh-strength metallic materials by providing a pathway for alloy design. Tungsten-based alloys with ultrahigh strength and ductility are in high demand for a wide range of applications, potentially for fusion reactors. Here the authors develop a tungsten refractory high-entropy alloy with high strength (~2.15 GPa) and sufficient ductility (~15%). [ABSTRACT FROM AUTHOR]

Shear localization is one of the most important failure mechanisms subjected to high-strain-rate deformation and has significant effects on the process, plastic deformation, and catastrophic failure of a material. Shear localization was observed in serrated chips produced during the high-speed cutting of the CoCrFeMnNi high-entropy alloy. Electron backscatter diffraction was performed to systematically investigate microstructural evolution during shear banding. The elongation and subdivision of the narrow grains were observed in the areas adjacent to the shear band. The microstructure inside the shear band was found to be composed of equiaxed ultrafine grains. The results reveal that grain subdivision and dynamic recrystallization might have significant roles in the microstructural evolution of shear bands. These results offer key insights into our understanding of shear localization and high-speed machining behavior for high entropy alloys. [ABSTRACT FROM AUTHOR]

Numerous studies have demonstrated the widespread presence of chemical short-range order (SRO) in medium and high entropy alloys (M/HEAs). However, the mechanism of their influence on macroscopic mechanical behavior remains to be understood. In this paper, we propose a novel dislocation-based model of crystal plasticity, by considering both the dislocation blocking and coplanar slip induced by SRO. The effect of SRO on the plastic deformation of CoCrNi MEAs was investigated. We found that the yield strength increases monotonically with increasing SRO-induced slip resistance, but the elongation first appeared to increase and then decreased. Further analysis suggested that the plastic elongation is a result of the competition between grain rotation-induced deformation coordination and stress concentration, which depends on the slip resistance of the SRO. [ABSTRACT FROM AUTHOR]

The effect of Al addition on the microstructural evolution, hardness, and deformation behavior of a nanostructured CrCoNi medium entropy alloy prepared by co‐sputtering is studied in detail. With an increase in the Al content, the hardness of the alloy first increased (reaching 13.8 GPa) and then decreased (10.7 GPa), while the microstructure changed from nanocrystalline to a nanocrystalline/amorphous dual‐phase structure. During plastic deformation, the appropriate amounts of the amorphous region and nanocrystalline mixed structure prevent shearing and grain rotation. Moreover, the amorphous shell also acts as a dislocation source that emitted and absorbed dislocations constantly and prevented grain boundary sliding to some extent. This work provides a novel approach to improve the mechanical properties of nanostructured medium entropy alloy films by controlling their composition and microstructure. [ABSTRACT FROM AUTHOR]

This work proposes an effective design of bioactive 3D-printed Ti-6Al-4V scaffold with the CaO-MgO-SiO 2 glass-ceramic coating to realize a comparable elastic modulus of bone tissue and boost osteogenic differentiation. The improved elastic modulus and stiffness of Ti alloy were achieved via effectively increasing surface area of Ti alloy to reduce stress shielding effect. A hydrophilic surface and bioactive glass-ceramic coating were conducted via chemical etching and heat-treatment under argon atmosphere to enhance cells attachment and boost cell proliferation and osteogenic differentiation. The expression of osteogenic genes in bioactive CaO-MgO-SiO 2 glass-ceramic was evaluated through ALP, OPN, Runx2, and Col1A1 gene markers to explore the mechanism of superior osteogenic differentiation. Significant increase in OPN expression level confirmed the effect of CaO-MgO-SiO 2 coating for the enhancement of osteogenic bioactivity. This work provides a feasible approach through surface etching and bioactive CaO-MgO-SiO 2 glass-ceramic coating on the Ti alloy surface to enhance bioactivity and osteogenesis. [Display omitted] • A compatible bone tissue of 3D-printed Ti-6Al-4V scaffold with the novel bioactive CaO-MgO-SiO 2 glass-ceramic coating. • A superior surface modification to enhance cells attachment and boost cell proliferation and osteogenic differentiation. • This work provides a feasible approach on the Ti-alloy surface to enhance bioactivity and osteogenesis. [ABSTRACT FROM AUTHOR]

Zero thermal expansion (ZTE) alloys possess unique dimensional stability, high thermal and electrical conductivities. Their practical application under heat and stress is however limited by their inherent brittleness because ZTE and plasticity are generally exclusive in a single-phase material. Besides, the performance of ZTE alloys is highly sensitive to change of compositions, so conventional synthesis methods such as alloying or the design of multiphase to improve its thermal and mechanical properties are usually inapplicable. In this study, by adopting a one-step eutectic reaction method, we overcome this challenge. A natural dual-phase composite with ZTE and plasticity was synthesized by melting 4 atom% holmium with pure iron. The dual-phase alloy shows moderate plasticity and strength, axial zero thermal expansion, and stable thermal cycling performance as well as low cost. By using synchrotron X-ray diffraction, in-situ neutron diffraction and microscopy, the critical mechanism of dual-phase synergy on both thermal expansion regulation and mechanical property enhancement is revealed. These results demonstrate that eutectic reaction is likely to be a universal and effective method for the design of high-performance intermetallic-compound-based ZTE alloys. Zero thermal expansion alloys have unique dimensional stability but suffer from inherent brittleness and compositional sensitivity. Here the authors present the one-step eutectic reaction approach to produce a dual-phase alloy with an axial zero expansion and promising mechanical properties. [ABSTRACT FROM AUTHOR]

Developing affordable and light high-temperature materials alternative to Ni-base superalloys has significantly increased the efforts in designing advanced ferritic superalloys. However, currently developed ferritic superalloys still exhibit low high-temperature strengths, which limits their usage. Here we use a CALPHAD-based high-throughput computational method to design light, strong, and low-cost high-entropy alloys for elevated-temperature applications. Through the high-throughput screening, precipitation-strengthened lightweight high-entropy alloys are discovered from thousands of initial compositions, which exhibit enhanced strengths compared to other counterparts at room and elevated temperatures. The experimental and theoretical understanding of both successful and failed cases in their strengthening mechanisms and order-disorder transitions further improves the accuracy of the thermodynamic database of the discovered alloy system. This study shows that integrating high-throughput screening, multiscale modeling, and experimental validation proves to be efficient and useful in accelerating the discovery of advanced precipitation-strengthened structural materials tuned by the high-entropy alloy concept. Advanced screening strategies for the design of high-entropy alloys are highly desirable. Here the authors use the project-oriented design strategy and CALPHAD-based high-throughput calculation tool to rapidly screen promising Al-Cr-Fe-Mn-Ti structural HEAs for high-temperature applications. [ABSTRACT FROM AUTHOR]

• Both the tensile strength and plasticity of the CrMnFeCoNi high-entropy alloy were enhanced significantly at high strain rates. • High strain rate embrittlement effect of CrMnFeCoNi high-entropy alloy is suppressed. • Cooperation of twins and dislocations is the crucial mechanism for the synchronous enhancement of strength and plasticity in this alloy under dynamic tension. • A thermo-viscoplastic dynamic constitutive model based on dislocation and twin evolution was developed. High-entropy alloys (HEAs), recently emerging alloy materials with numerous excellent performances, may have a wide application prospect in impact engineering. However, previous research regarding the mechanical behavior of HEAs has primarily focused on quasi-static testing, whereas the dynamic mechanical behavior of HEAs at high strain rates remains elusive. In this paper, the unusual simultaneous strength-plasticity enhancement and the inhibition of the high strain rate embrittlement of CrMnFeCoNi HEA in impact tension were revealed via split Hopkinson tensile bar (SHTB) with high-speed photography. Quantitative microstructural analysis indicates that the cooperation of twins and dislocations is the crucial mechanism for the synchronous enhancement of strength-plasticity in this alloy under impact tension. A thermo-viscoplastic constitutive model based on dislocations and twins evolution was developed to describe dynamic mechanical behavior. The high plastic hardening under dynamic tension was revealed to be induced by high dislocation forest hardening and strong resistance of twins to dislocation motion. The excellent combination of dynamic strength-plasticity of CrMnFeCoNi HEA makes it becoming a promising candidate for impact engineering applications. [ABSTRACT FROM AUTHOR]

Micron-sized CoCrNi medium-entropy alloy (MEA) wires are successfully fabricated by Taylor-Ulitovsky method for the first time. The wires of two different sizes, with diameters of 40 and 100 microns, exhibit an excellent combination of tensile strength and ductility. In-depth microstructure characterization indicates the superior mechanical properties stem from the synergy of Lomer-Cottrell locks, mechanical nano-twinning and HCP stacking. Surprisingly, an anomalous size effect is presented in the tension of these microwires, i.e., the much higher tension strength and ductility are observed in the 40 micron-wire, in sharp contrast to conventional single-principal element alloys only showing negligibly minor tension size effect. Much higher density of geometrically necessary dislocation accompanying heterogeneous deformation is observed in 40 micron-wire, leading to a high strain gradient, which is in turn joined with multiple deformation twins giving rise to high strength and ductility in 40 micron-wire. [Display omitted] [ABSTRACT FROM AUTHOR]

The application of metal catalysis has gained prominence as a study area in recent years. In this work, we use adsorptive reduction and calcination to create Au–Pd alloy catalysts on COCN-2 with varying metal loadings. The plasma resonance effect of the alloys increases the photoresponse of the catalysts, and the engineering of nitrogen defects strengthens the strong bonds between Au–Pd alloy particles and carbon nitride graphite, optimizing the electronic structure, encouraging electron-directed migration, and increasing the efficiency of the reduction reaction. As a result, the efficiency of hydrogen generation by the Au–Pd 0.6 /COCN-2 catalyst is 5.089 mmol g−1 h−1, which is 2367 times higher than that of the g-C 3 N 4 catalyst. Our findings highlight the crucial part that flaws play in strengthening the strong bonds that exist between the metal and the support, which enhances photocatalytic hydrogen generation. This work offers insightful information about creating effective photocatalysts. • A series of Au–Pd/COCN catalysts were prepared via a facile method. • The performance of Au–Pd 0.6 /COCN-2 reached 5.089 mmol g−1 h−1, which is 2367 times higher than the pristine g-C 3 N 4. • A series of investigations were conducted to reveal the mechanism. [ABSTRACT FROM AUTHOR]

Metallic wires with high strength-ductility at both room and cryogenic temperatures are always pursued for engineering applications. However, traditional metallic wires are tortured inevitably by strength-ductility trade-off dilemma. In this work, a gradient heterogeneous lamella structure, characterized with hard gradient-distributed B2 lamellae embedded in soft FCC lamellae matrix, is introduced into AlCoCrFeNi 2.1 eutectic high entropy alloy (EHEA) wire by well-designed multiple-stage heavy-drawn and heat treatment processes, which achieves an outstanding strength-ductility synergy. This EHEA wire exhibits not only high tensile strength of 1.85 GPa and sufficient uniform elongation of ∼12% at room temperature, but also ultra-high tensile strength of 2.52 GPa and even slightly elevated uniform elongation of ∼14% at cryogenic temperature. In-depth microstructure characterization indicates that the gradient heterogeneous lamella structure facilitates a radial gradient distribution of geometrically necessary dislocation (GND) during tension, i.e., the GND density decreases gradually from the surface region to the central region of EHEA wire, which induces pronounced strain gradient strengthening effect and thus greatly benefits the mechanical properties. Intriguingly, at cryogenic temperature, dense cross-slip which gives rise to intensively dynamic microstructure refinement is firstly observed in the B2 phase of EHEA wire. The activation of cross-slip provides sufficient ductility while inducing evidently dynamic Hall-Petch effect, becoming the most effective deformation mechanism contributing to the unprecedented cryogenic tension properties. This work sheds light on designing ultra-strong EHEA wire and other advanced metallic wires. [Display omitted] [ABSTRACT FROM AUTHOR]

High-strength metallic wire is a vital bearing structure used in many industrial fields. Impact loads often challenge the service safety of metal wire in engineering applications. However, few studies have been made on the dynamic mechanical behavior of metallic wires, especially for newly developed high-entropy alloy wires. By equipping split Hopkinson tension bar (SHTB) with specially designed test fixtures, we have carried out a systematic study on the dynamic deformation behavior of the heavily-drawn CoCrNi medium-entropy alloy (MEA) wire in impact tension at both room and cryogenic temperatures. We show that these millimeter-diameter MEA wires with nano-scale grains can achieve an excellent combination of impact tensile strength and ductility at 293 K and 77 K. More interestingly, we find that the strength and ductility of the MEA wire were enhanced simultaneously with decreasing temperature and increasing strain rate. Detailed microstructure characterizations and molecular dynamics simulations reveal that the increased strength and ductility at coupled high strain and low temperature resulted from the multiplication and thinning of nanoscale twins, which further caused additional strengthening and toughening mechanisms such as stack faulting net and secondary twin. This study highlights the advantage of CrCoNi MEA wire for cryogenic temperature and impact applications and provides an experimental reference for the design and evaluation of high-strength metal wires under such extreme conditions. • Two types of Hopkinson tie bar clamps are designed to obtain accurate wire dynamic stress-strain curves. • The cold-drawn wire exhibits an ultrahigh strength at cryogenic temperature and dynamic tension. • The CoCrNi wires can achieve a good combination of high strength and large engineering elongation via heat treatment. [ABSTRACT FROM AUTHOR]

Fatigue properties are essential for structural materials in industrial applications. High-entropy alloys are promising fatigue-resistant alloys with high strengths and good ductilities. In this study, the B2 precipitate significantly increased the yield strength of the Al 0.3 CoCrFeNi high-entropy alloy but at the same time decreased the low-cycle fatigue life. A detailed investigation of the underlying mechanisms will provide critical insights into the precipitate effect on the fatigue performance of high-entropy alloys. Here, the Al 0.3 CoCrFeNi alloys with single face-centered-cubic (FCC) phase and with FCC + B2 phases are used for the investigation of the low-cycle fatigue behavior by combining in situ neutron diffraction measurements and elastic-viscoplastic self-consistent modeling. The simulation results indicate that the B2 precipitates highly increased the back stresses during cyclic loading by facilitating the kinematic hardening in the matrix, while the effect of dynamic recovery is relatively weak. The increase in back stresses provides more fatigue-crack-initiation sites and thus the damage accumulation, which will further lead to a shorter fatigue life. [Display omitted] • The B2 precipitates increased the yield strength and decrease the LCF life in the Al 0.3 CoCrFeNi HEA. • Lattice strain and full-width half-maximum results were obtained from in situ neutron diffraction. • Diffraction experiments and crystal plasticity modeling reveal the role played by B2 precipitates. [ABSTRACT FROM AUTHOR]

• The radii of the nanoscale precipitates are dramatically smaller in the annealed Cu-2Ag-0.14La alloy than in the annealed Cu-2Ag alloy. • The grain size of annealed Cu-2Ag-0.14La alloy is always smaller than that of the annealed Cu-2Ag alloy from 400 °C to 650 °C. • Precipitation strengthening of nanoscale precipitates in the matrix and grain-boundary strengthening during grain refinement substantially improve the yield strength of the Cu-2Ag-0.14La alloy. [Display omitted] A new Cu–2Ag–0.14La alloy is developed to enhance the mechanical property and electrical conductivity with inducement of Ag-rich primary phases and finer nanoscale Ag precipitates. The microstructural evolution and mechanical properties of Cu–2Ag–0.14La and Cu–2Ag alloys obtained by drawing and annealing were then summarized and analyzed. The results indicate that both the yielding and ultimate tensile strengths of annealed Cu–2Ag-0.14La alloy were reinforced after La modification. The average grain sizes of two alloys increase during annealing, but the size ratio (R Cu-2Ag-0.14La /R Cu-2Ag) dramatically varies with rising the heat temperature, evolving from 70.48% at 400 °C to 43.78% at 650 °C. Meanwhile, it is found that the refined grains sizes in Cu-2Ag-0.14La alloy are closely related to the nano-scale precipitates (~450 nm), which hinder the formation of subgrain boundaries at 400 °C, and impose a stronger pinning effect on boundary migration of recrystallized grains during annealing (≥ 450 °C). Consequently, higher hardness and electrical conductivity are contributed by grain refinement and dispersion strengthening of the nanosized phases. [ABSTRACT FROM AUTHOR]

The cyclic stability of hydrogen absorption and desorption is an important indicator of hydrogen storage alloy. The decay mechanism was roundly investigated by controlling the depth of dehydrogenation (DOD) of the V 40 Ti 25.5 Cr 26.5 Fe 8 alloy during the process of hydrogen ab/desorption cycles. The V 40 Ti 25.5 Cr 26.5 Fe 8 alloy exhibits the hydrogen desorption capacity of 2.36 wt% at 323 K in the first cycle. After 30 cycles, the decay rate of the hydrogen desorption capacity is only 4.37 % at 40 % DOD, but rises to 8.74 % at 100 % DOD. The hydrogen desorption capacity (C), plateau pressure (P) and micro-strains (S) all show an "acceleration followed by slowing" exponential variation trend with the increase of cycle number (x). Additionally, any two of C , P and S show linear correlation. It is considered that the micro-strains in the crystal lattice is the main factor for the decay of the hydrogen desorption capacity and the plateau pressure. On the premise of ensuring the valid hydrogen storage capacity to meet the requirements of the application, properly reducing DOD per cycle can effectively reduce the micro-strains accumulation and cell volume expansion, thus improving the cyclic stability of the alloy. Moreover, the application of this alloy in a fuel cell bicycle was investigated, and the total range and mileage per unit weight of the alloy are up to 100.8 km and 15.7 km/kg, respectively. Compared with the lead-acid battery, lithium-ion battery and LaNi 5 -based hydrogen fuel cell, the V-Ti-Cr-Fe-based fuel cell shows significant advantages. ● A bran-new method was proposed to slow down the decay of the dehydrogenation capacity of the V 40 Ti 25.5 Cr 26.5 Fe 8 alloy. ● The alloy decay rate of the dehydrogenation capacity is only 4.37% after 30 cycles at 40% DOD, only half that at 100% DOD. ● Six functions were proposed to explain the influences of the micro-strains in the lattice. ● This alloy fuel cell shows significant advantages compared with other batteries through application in a fuel cell bicycle. [ABSTRACT FROM AUTHOR]

CoCrFeMnNi high-entropy alloys (HEAs) are additively manufactured by laser directed energy deposition (L-DED) and laser powder bed fusion (L-PBF) processes. Comparative studies are conducted for the microstructures and deformation mechanisms of L -DED and L -PBF samples. In both types of samples, highly heterogeneous microstructures are formed, consisting of columnar grains, solidification cells, and dislocation networks. However, substantial differences are measured in the crystallographic texture, cell size, and elemental distribution. Deeper melt pools in the L -DED samples promote a mixed crystallographic texture of <101>/<111> as opposed to <001> along the build direction in the L -PBF samples. The <101>/<111> texture elevates the flow stresses and facilitates the activation of deformation twins in the L -DED samples. Moreover, their larger solidification cell sizes and associated chemical segregation across cell walls increase the dislocation storage capability and resistance to dislocation motion, leading to profuse planar slip bands and microbands during plastic deformation. The enhanced plastic deformation capabilities in the L -DED samples give rise to more sustained strain hardening and thus higher ductility compared to the L -PBF samples. Our work not only provides fundamental insights into the deformation mechanisms of additively manufactured HEAs, but also underscores the critical impact of processing conditions on the solidification microstructure and material design by additive manufacturing. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Adding the Cu led to the formation of Cr-enriched precipitates in the matrix. • The Cr 7 C 3 precipitate in the CoCrMo-4Cu was partially coherent with Cu nanoparticle. • The Cr-enriched precipitates were the critical contributor to enhancing the tribology property. • The corrosion resistance of CoCrMo alloy was enhanced as the 2 and 3 wt% Cu added into CoCrMo alloy. In this study, the cobalt-chromium-molybdenum (CoCrMo) alloys containing varying Cu contents (CCM- x Cu, x = 0, 2, 3, 4 wt%) were fabricated via the selected laser melting (SLM) method. The influences of Cu content on tribological performance and corrosion resistance were investigated. The 2 and 3 wt% Cu contributed to inhibiting the generation of the HCP phase, whereas the inhibitory effect was quite limited at 4 wt% Cu. Notably, 4 wt% Cu led to the formation of Cr-enrich precipitates in the matrix, which was partially coherent with the Cu nanoparticle. The corrosion resistance of the CCM alloy was enhanced as the 2 and 3 wt% Cu added into the CCM alloy, contrarily, which deteriorated when Cu content reached 4 wt%. For the CCM-2Cu and CCM-3Cu, Cr-precipitates played a major role in enhancing the wear resistance, while the Cu lubrication effect working in coordination with Cr-precipitates determined that for the CCM-4Cu. This study was expected to achieve better tribology and corrosion properties of SLM-produced CCM alloys by tailoring microstructure through the Cu element. [ABSTRACT FROM AUTHOR]

Temperature is a critical parameter that affects both the electrochemical reactivity and the crystal nucleation / growth during the conversion treatment of Mg alloys, but the increase of operating temperature negates the bath reactivity, thus degrading the protectiveness of coating. However, preheating the Mg substrate will not alter the bath chemistry. In this work, Mg substrates were preheated to various temperature values, then were conversion treated in a bath at 60 °C. Results prove that a preheating temperature higher than the bath temperature could effectively enhance coating protectiveness, which was attributed to the enhanced crystal precipitation kinetics at reaction fronts. [ABSTRACT FROM AUTHOR]

[Display omitted] • In-situ neutron diffraction measured the elastic properties of NbV, NbTiV, and MoNbV alloys, which are consistent with first-principles calculations. • Adding Ti elements into the NbV alloy results in the formation of the elastically isotropic NbTiV alloy. • This work provides valuable insights into the design of ductile and strong refractory high-entropy alloys by tuning the elastic properties. Elastic properties are essential to the mechanical performance of materials, and therefore, can be tuned to design high-performance materials. In this study, the elastic constants of the equiatomic ternary refractory multi-principal-element alloys, NbTiV, and MoNbV, were investigated, using in-situ neutron diffraction and first-principles calculations. The experimentally measured and theoretically predicted elastic constants show a good agreement. The alloying effect of adding Ti and Mo into NbV base alloy on the elastic constants is studied. Particularly, adding Ti elements into the NbV alloy results in the increase of the Zener anisotropy ratio from 0.59 to 0.99, leading to the formation of the elastically isotropic NbTiV alloy, while the addition of Mo decreases the anisotropy ratio to 0.52. Pugh's ratio (B / G), Cauchy pressure (C 12 - C 44), and Poisson's ratio (ν) are used to predict the brittle/ductile nature of the studied alloys, which is consistent with the mechanical results. The present work provides valuable insights into the design of ductile and strong refractory high-entropy alloys by tuning the elastic properties. [ABSTRACT FROM AUTHOR]

A new Cu–2 wt% Ag–0.15 wt% La alloy composed of large-size Ag-rich primary phases was processed into wire billets by successive drawing, annealing and continuous extrusion forming (CONFORM). The microstructural evolution and mechanical properties of the samples obtained by drawing, annealing and CONFORM were then investigated. The results indicate that a desirable combination of high ultimate tensile strength (300 MPa) and elongation (49.5%) was obtained after CONFORM. The latter allowed the microstructure to be significantly refined via an almost full dynamic recrystallization (DRX), with grain sizes of ~ 1 μm. In addition, the large-size primary phases were broken into dispersed nanophases with an average size of 800 nm. The dispersed phases promoted the DRX of the matrix via particle-stimulated nucleation. As a result, the enhanced toughness (11145.98 MPa·%) is contributed by grain refinement and dispersion strengthening of the nanosized phases. [ABSTRACT FROM AUTHOR]