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The microstructure of Mg-12Y-1Al alloy with solution treatment and aging treatment was studied by optical microscope, X-ray diffraction and scanning electron microscope. The mechanical properties of the alloy before and after heat treatment at room temperature and 200 ℃ were analyzed by tensile test, and the corrosion resistance of the alloy before and after heat treatment was tested by electrochemical methods. The results show that the as-cast microstructure of Mg-12Y-1Al alloy is composed of α-Mg matrix, Mg24Y5 phase and Al2Y phase. Mg-12Y-1Al alloy has excellent high-temperature thermal stability. After solution treatment at 520 ℃ for 16 h(T4), the grain size does not increase, and new long period stacking ordered(LPSO) phase forms; the subsequent aging treatment at 225 ℃ for 30 h(T6) has little effect on the microstructure. Compared with the properties at room temperature, the ultimate tensile strength of T4 alloy at 200 ℃ does not decrease, but the elongation increases from 1.3% to 12.5%. Moreover, the corrosion resistance of Mg-12Y-1Al alloy is improved after solution and aging treatment, and the corrosion current density decreases from 2.799×10-5 A/cm2 to 1.551×10-5 A/cm2.

Macro-defect free (MDF) gypsum is characterized by high strength and has the potential designed to advanced functionalization materials. However, the application of MDF gypsum is still limited by its poor water resistance. Here, we propose to modify the gypsum surface to hydrophobicity at molecule scale by adding potassium methylsilicate. The compressive strength, softening coefficients, and water absorption were subjected to rigorous testing, while elucidating the underlying mechanisms of water resistance enhancement through micro-structural analysis and organic-inorganic interactions. The results show that when adding 0.25% potassium methylsilicate, the wet compressive strength, softening coefficients are increased by 30.1%, 28%, respectively. And potassium methylsilicate can change the gypsum surface to hydrophobicity, which delaying the initial rapid water absorption stage and decrease both the 2 h and 24 h water absorption. The addition of potassium methylsilicate leads to a reduction in the dried compressive strength, attributed to the decrease in intrinsic dihydrate crystal strength. Upon the introduction of potassium methylsilicate, there is a transformation in gypsum crystal morphology from strip-like to lamellar structures. This alteration is accompanied by the formation of a potassium methylsilicate film coats the surface of gypsum, impeding water-gypsum contact. The potassium methylsilicate film coats on the surface of gypsum, which hinders the contact of water and gypsum.

In order to study the effect of Al content on the microstructure properties of FeCoCrNi alloy, AlxCoCrFeNi high-entropy alloy (0≤x≤0.9) was prepared by multi-channel laser cladding. The phase composition, microstructure, chemical composition and hardness of the alloy were test by X-ray diffractometry, metallography microscope, scanning electron microscope, electron probe and microhardness tester. The results show that with the increase of Al content, AlxCoCrFeNi high-entropy alloy changes from single FCC phase (x≤0.35) to FCC+BCC biphase structure (0.35 < x < 0.85), and finally to BCC structure (x≥0.85). The microstructure of the high entropy alloy consists of epitaxial columnar dendrites and uniform equiaxed dendrites. When Al content reaches to x=0.5, characteristic structure of spinodal decomposition with alternating light and dark contrast starts to appear between the dendrites, which consists of disordered phase A2 and ordered phase B2.The microhardness test results show that the microhardness of AlxCoCrFeNi alloys almost increases with the increasing Al content and a total of 146% improvement has been achieved when the Al content increases from x=0 to x=0.9. It should be noted that cracks begin to appear in the alloy when the Al content increases to a certain value (x≥0.6).The size and density of cracks increase with the increase of Al content.There are two main reasons. Firstly, the hot-cracking increases since the solidification range widen and their viscosity values near the solidification temperatures increase with the increasing Al content.Besides, cold cracking also increases as the brittle BCC and σ phases increase with the increasing Al content.

The mechanical properties of direct laser deposition (DLD) parts are crucial for engineering applications, which are determined by the microstructure and texture. To achieve fine microstructure and higher mechanical performance, pulsed laser deposition is used to generate less heat accumulation and a higher cooling rate. However, the relationship between microstructure and thermal history is difficult to investigate due to the transient temperature change. In this work, a three-dimensional numerical model is developed to study the thermal behavior of the molten pool in the continuous laser deposition (CLD), the continuous pulsed laser deposition (CPLD), and the interval pulsed laser deposition (IPLD) processes. The microstructure of the deposition samples is investigated by optical microscope and electron back-scattered diffraction. The mechanical response of the deposition samples is investigated by tensile test and microhardness test. Compared with the CLD, CPLD, and IPLD result in higher temperature gradient and cooling rate, long columnar grains, and a strong fiber texture. However, grains with larger sizes and a texture with a herringbone pattern due to the change of heat flow are obtained in CLD samples. The test values of IPLD samples show higher tensile strength, higher yield strength, lower ductility, and higher hardness values. This research brings about a perspective for studying the thermal effects of deposition layers and a novelty deposition process to obtain specific microstructures and better mechanical properties.

In this work, the oxidation behavior of Inconel 718 superalloy fabricated by selective laser melting was investigated in the CO2 atmosphere at 1000 and 1100 °C. Results show that the structure of the oxide scales is strongly dependent on the grain position (grain boundary and grain interior) and the oxidation temperature. It forms six-layer and four-layer oxide scales at the grain boundary region after 300 min oxidation at 1000 and 1100 °C, respectively, producing three-layer oxide scales in the intragranular area. The formation mechanisms of the oxide scale were discussed. Additionally, the Kirkendall voids and internal oxidation in the matrix preferentially form at 1100 °C.

The use of metal-coated ceramic powders not only effectively enhances the wettability of the metal–ceramic interface but also promotes a more uniform microstructure in Ti(C,N)-based cermets, which is advantageous for improving their mechanical properties. In this study, ultrafine Co- and Ni-coated (Ti,W,Mo,Ta)(C,N) powders were synthesized via the spray-drying-in-situ carbothermal reduction method. Subsequently, Ti(C,N)-based cermets were effectively fabricated using the as-prepared ultrafine Co- and Ni-coated (Ti,W,Mo,Ta)(C,N) powders. The impact of reaction temperature, heating rate, and isothermal time on the phase and microstructure of prepared powders was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Additionally, the microstructure of the as-sintered cermets was experimentally investigated. The findings reveal that the complete reduction of Co and Ni metal salts, pre-coated on the surface of (Ti,W,Mo,Ta)(C,N) particles, can be achieved through rapid heating (10 °C/min) in a specific temperature range (600–1000 °C) with an isothermal time of 3 h at a lower reduction temperature (1000 °C). The synthesized powders have only two phases: the (Ti,W,Mo,Ta)(C,N) phase and Co/Ni phase, and no other heterogeneous phases were observed with an oxygen content of 0.261 wt.%. Notably, the conventional core–rim structure was not dominant in the cermets obtained from the prepared Co- and Ni-coated (Ti,W,Mo,Ta)(C,N) powders. Moreover, the heterogeneous segregation effect of the Co/Ni coating on the ultrafine powder particles resulted in a finer microstructure than the traditional cermets with the same composition. However, the grain size is mainly in the range of 0.5–0.8 μm. The weaker residual stresses at the core and rim interfaces and the finer particle distributions could theoretically enhance the toughness of Ti(C,N)-based cermets, simultaneously.

The use of seawater and sea sand as replacements for fresh water and river sand in the preparation of seawater and sea sand concrete can effectively address issues such as high transportation costs, extended construction periods, and resource wastage. Nevertheless, in northern coastal areas, the problem of concrete durability in the complex and changing marine environment is more prominent. Research on the durability of seawater sea sand concrete is beneficial to the widening of its application range. To investigate the impact of glass fiber (GF) and polyvinyl alcohol fiber (PVA) with different blending methods on the seawater freeze–thaw resistance of seawater sea sand concrete (SSC), corresponding specimens were prepared, and seawater freeze–thaw cycling tests were conducted. By adopting the slow-freezing method and combining macro-structure and micro-morphology, the damage mechanism and the deterioration law of fiber-reinforced SSC under seawater freezing and thawing were investigated. The results indicate that, macroscopically, the incorporation of GF and PVA can effectively mitigate the damage to the matrix and reduce the effects of external erosive substances on the rate of strength loss, the rate of mass loss, and the relative dynamic elastic modulus. After 75 cycles, the SSC with a total volume doping of 0.3% and a blending ratio of 1:1 showed a 41.23% and 27.55% reduction in mass loss and strength loss, respectively, and a 29.9% improvement in relative dynamic elastic modulus compared with the basic group. Microscopic analysis reveals that the combined effect of freezing and expansion forces, the expansive substances generated by seawater intrusion into the interior of the matrix, and salt crystallization all weaken the bond between aggregate and mortar, leading to accelerated deterioration of the concrete. The incorporation of fibers enables the matrix to become denser and improves its crack-resistant properties, resulting in a better durability than that of the basic group. The damage prediction model established by the NSGM(1,N) model of gray system theory exhibits high accuracy and is suitable for long-term prediction, accurately predicting the damage of seawater sea sand concrete under seawater freeze–thaw coupling.

To effectively solve the problems of environmental pollution and resource waste caused by steel slag and open up a new field of application of steel slag, the porous magnetic steel slag abrasive was prepared by combining the gas quenching process with steel slag as the main raw material. Besides, and the micro-morphology, the pore structure, the magnetic properties, the mechanical properties and the abrasive properties of steel slag abrasive were characterized by field emission scanning electron microscope, high-performance automatic mercury porosimeter, magnetometer, etc. The results show that the steel slag abrasive is monodisperse spherical, and there are disordered pores arranged in round or elliptical shape on its surface and cross section. The porosity of abrasive sample is 37% to 45%, and the pore volume is 0.18 to 0.23 mL/g. Under the action of external magnetic field, with the increase of the particle size of the abrasive sample, its hysteresis loop shifts clockwise and presents a narrow “S” type closed curve. The abrasive sample shows typical ferrous magnetism, which can effectively improve the surface quality of aluminum alloy workpiece, and the surface roughness Ra of the workpiece is reduced from 3.2 µm to 0.7 µm.

The hot deformation behavior of the wrought Mg–Gd−Y–Zn–Zr alloy was studied by uniaxial tensile tests conducted at various temperatures (350–500 °C) and strain rates (0.1–0.0001s−1). Furthermore, the effects of the deformation parameter on the true stress−strain curves, microstructure, fracture characteristics, and fracture mechanisms were discussed, and a damage model for predicting fracture strain was established. The results are as follows. The increasing temperature or the decreasing strain rate reduce the peak stress and increase the fracture strain, except for 500 °C/0.0001s−1. The increasing in the fracture strain is attributed to the easier activation of multi−slip, the smaller size of broken 14H−LPSO during deformation, the higher fraction of fine grain generated by DRX. The β phase around the grain boundary will gradually disappear with the decrease of strain rate at high temperature (450 °C and 500 °C), which will cause DRXed−grain coarsening. Especially the alloy deformed at 500 °C/0.0001s−1, the grains are significantly coarsened. Thus, the fracture strain of the alloy deformed at 500 °C/0.0001s−1 is not greater than that of the alloy deformed at 500 °C/0.001s−1. The fracture morphology changes from the coexistence of cleavage surfaces and dimple to dimple with increasing deformation temperature and decreasing strain rate. In addition, the fracture damage predicted using the fracture damage model agreed well with the experimental results, with a maximum relative error of only 8.8%.

In order to improve the comprehensive mechanical properties of the welded joints of the 5A06 aluminum alloy, friction stir welded (FSW) joints were subjected to deep cryogenic treatment (DCT). The microstructure and mechanical properties were characterised using metallographic microscopy, x-ray diffractometer (XRD), energy spectrometer, microhardness tests, and tensile tests. The experimental results show that DCT refines the structure significantly due to the large temperature difference. This refinement results from an increase in Mg atoms within the α -Al solid solution through the precipitation of Al atoms, forming the Al _3 Mg _2 phase. This enhancement in plasticity is achieved through dispersion distribution. Moreover, as the treatment time of DCT increases, the mechanical properties of the welded joint also improve significantly. The microhardness of the welding joint peaked at DCT3h, rising from 78.8 HV at DCT0h to 87.2 HV at DCT3h. Meanwhile, the tensile strength of the joint reached its maximum at DCT12h, rising from 358.7 MPa at DC0h to 385.3 MPa at DCT12h, representing a 7.4% increase. These experimental results underscore the significant impact of DCT on improving the welded joints.

The effects of deep cryogenic treatment (DCT) on the tensile property and microstructure of Mg-9Gd-4Y–2Zn-0.5Zr(wt.%) alloy were investigated by comparing the alloy treated by solution treatment, deep cryogenic treatment and aging treatment (ST + DCT + AT) and that treated by solution treatment and aging treatment (ST + AT). The lamellar 14H-type long-period stacking ordered (14H-LPSO) in grain was precipitated in the alloy treated by ST + AT. However, the particle and needle-like Mg5RE (RE = Gd, Y) phases instead of the lamellar 14H-LPSO were precipitated, and a high-density dislocation existed in the alloy treated by ST + DCT. The greater ultimate tensile strength (UTS) and yield strength (YS) of the alloy treated by ST + DCT + AT were obtained because of the precipitation of the Mg5RE phases. The trend, the UTS and YS firstly increased then decreased with the increasing of soaking time, is corresponding to the volume fraction increasing and size-coarsening of Mg5RE precipitates, respectively. The greater elongation (EL) was obtained after the short-time DCT for 0–2 h (DCT0h-DCT2h) and the smaller EL was obtained for the long soaking time (>DCT2h). The fracture mode of the samples is all quasi-cleavage fracture.

The effect of sintering temperature on the microstructure and electrical properties of ZnO–Bi2O3 varistor ceramics was studied in the present work. Results demonstrate that the Bi-rich phase ZnBi38O60 is generated at the ZnO grain boundaries in the prepared varistor ceramics over a range of 850–1000°C. As the sintering temperature increases, the Bi-rich insulator layer tends to widen, and the average grain size increases to 13.22 μm. The switching field, breakdown strength ( E 1 mA ), and nonlinear coefficient (α) increase, while the leakage current density ( J L ) decreases, because of an increase in barrier height ( φ B ). In addition, the sintering temperature promotes a decrease in the dielectric constant ( ε a ) and an increase in dielectric loss. The ZnO–Bi2O3 varistor ceramic sintered at 1000°C exhibits excellent overall electrical properties, with a switching field of 228.04 V/mm, E 1 mA of 379.76 V/mm, α of 6.02, J L of 140 μA/cm2, φ B of 0.39 eV, and ε a of 172.87 at 1 kHz. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) involving more than four elements, as emerging alloys, have brought about a paradigm shift in material design. The unprecedented compositional diversities and structural complexities of HEAs endow multidimensional exploration space and great potential for practical benefits, as well as a formidable challenge for synthesis. To further optimize performance and promote advanced applications, it is essential to synthesize HEAs with desired characteristics to satisfy the requirements in the application scenarios. The properties of HEAs are highly related to their chemical compositions, microstructure, and morphology. In this review, a comprehensive overview of the controllable synthesis of HEAs is provided, ranging from composition design to morphology control, structure construction, and surface/interface engineering. The fundamental parameters and advanced characterization related to HEAs are introduced. We also propose several critical directions for future development. This review can provide insight and an in-depth understanding of HEAs, accelerating the synthesis of the desired HEAs. [ABSTRACT FROM AUTHOR]

Molecular dynamics is a method of studying microstructure and properties by calculating and simulating the movement and interaction of molecules. The molecular dynamics simulation method has become an important method for studying the structural and dynamic characteristics of slag systems and can make up for the shortcomings of existing detection methods and experiments. Firstly, this paper analyzes the development process and application fields of molecular dynamics, summarizes the general simulation steps and software algorithms of molecular dynamics simulation methods, and discusses the advantages and disadvantages of the algorithms and the common functions of the software. Secondly, the research status and application progress of molecular dynamics simulation methods in the study of phosphate, silicate, aluminate and aluminosilicate are introduced. On this basis, a method of combining molecular dynamics simulation with laboratory experiments is proposed, which will help obtain more accurate simulation results. This review provides theoretical guidance and a technical framework for the effective analysis of the microstructure of different slag systems via molecular dynamics, so as to finally meet the needs of iron and steel enterprises in producing high-quality steel grades.

For investigating the influence mechanism underlying ultrafine Ti(C, N) within micron Ti(C, N)-based cermets, three cermets including diverse ultrafine Ti(C, N) contents were employed. In addition, for the prepared cermets, their sintering process, microstructure, and mechanical properties were systematically studied. According to our findings, adding ultrafine Ti(C, N) primarily affects the densification and shrinkage behavior in the solid-state sintering stage. Additionally, material-phase and microstructure evolution were investigated under the solid-state stage from 800 to 1300 °C. Adding ultrafine Ti(C, N) enhanced the diffusion and dissolution behavior of the secondary carbide (Mo2C, WC, and (Ta, Nb)C) under a lower sintering temperature of 1200 °C. Further, as sintering temperature increased, adding ultrafine Ti(C, N) enhanced heavy element transformation behaviors in the binder phase and accelerated solid-solution (Ti, Me) (C, N) phase formation. When the addition of ultrafine Ti(C, N) reached 40 wt%, the binder phase had increased its liquefying speed. Moreover, the cermet containing 40 wt% ultrafine Ti(C, N) displayed superb mechanical performances.

The effect of different heat inputs of 1.45 kJ/mm, 1.78 kJ/mm and 2.31 kJ/mm on the microstructure and mechanical properties of deposited metals of the self-developed AWS A5.28 E120C-K4 high strength steel flux-cored wire was studied by optical microscope, scanning electron microscope and mechanical property test. With the increase in heat input, the results showed that the microstructure of deposited metals became coarse. Acicular ferrite increased at first and then decreased, granular bainite increased and degenerated upper bainite and martensite decreased slightly. Under the low heat input of 1.45 kJ/mm, the cooling rate was fast and the element diffusion was uneven, which caused composition segregation and easy to form large size inclusions SiO2-TiC-CeAlO3 with weak binding to the matrix. Under the middle heat input of 1.78 kJ/mm, the composite rare earth inclusions in dimples were mainly TiC-CeAlO3. The dimples were small and uniformly distributed, and the dimple fracture mainly depended on the wall-breaking connection between medium-sized dimples rather than an intermediate media. Under the high heat input of 2.31 kJ/mm, SiO2 was easy to adhere to high melting point Al2O3 oxides to form irregular composite inclusions. Such irregular inclusions do not need to absorb too much energy to form necking. Finally, the integrated effects of microstructure and inclusions resulted in the optimum mechanical properties of deposited metals with a heat input of 1.78 kJ/mm, which was a tensile strength of 793 MPa and an average impact toughness at −40 °C of 56 J.

The relationship between pulsed laser processing parameters and epitaxial growth of alloy is essential to additive manufacturing technology in repairing and manufacturing nickel-based single crystal (SX) superalloys. In this paper, orthogonal experiments of Laser Direct Energy Deposition (DED-L) process have been designed to optimize the process for the epitaxial growth of the SX superalloy. The relationship between process parameters and epitaxial growth of SX superalloy is established in a radar map, which shows that low laser power, pulse width and powder feeding rate help epitaxial growth in the DED-L process. It is implied that increasing the powder feeding rate value in the process range decreases the epitaxial growth rate of the molten pool and increases manufacturing efficiency. The size of the cladding layer width is greatly influenced by laser power (reached 44%) and pulse width (reached 38%). The deposited heigh of the cladding layer is mainly influenced by pulse width (reached 45%) and powder feeding rate (reached 42%). The process parameters have a similar level (approximately 33%) of influence on the powder using efficiency.

In this study, Pickering emulsion gels were prepared by the self-gel method based on kappa carrageenan (kC). The effects of particle stabilizers and polysaccharide concentrations on the microstructure, rheological characteristics, and texture of Pickering emulsion gels stabilized by xanthan gum/lysozyme nanoparticles (XG/Ly NPs) with kC were discussed. The viscoelasticity of Pickering emulsion gels increased significantly with the increase of kC and XG/Ly NPs. The results of temperature sweep showed that the gel formation mainly depended on the kC addition. The XG/Ly NPs addition could accelerate the formation of Pickering emulsion gels and increase its melting temperature (Tmelt), which is helpful to improve the thermal stability of emulsion gels. Cryo-scanning electron microscope (Cryo-SEM) images revealed that Pickering emulsion gel has a porous network structure, and the oil droplets were well wrapped in the pores. The hardness increased significantly with the increase of XG/Ly NPs and kC. In particular, the Pickering emulsion gel hardness was up to 2.9 Newton (N) when the concentration of kC and XG/Ly NPs were 2%. The results showed that self-gelling polysaccharides, such as kC, could construct and regulate the structure and characteristics of Pickering emulsion gel. This study provides theoretical support for potential new applications of emulsion gels as functional colloids and delivery systems in the food industry.

The use of seawater and sea sand as replacements for fresh water and river sand in the preparation of seawater and sea sand concrete can effectively address issues such as high transportation costs, extended construction periods, and resource wastage. Nevertheless, in northern coastal areas, the problem of concrete durability in the complex and changing marine environment is more prominent. Research on the durability of seawater sea sand concrete is beneficial to the widening of its application range. To investigate the impact of glass fiber (GF) and polyvinyl alcohol fiber (PVA) with different blending methods on the seawater freeze–thaw resistance of seawater sea sand concrete (SSC), corresponding specimens were prepared, and seawater freeze–thaw cycling tests were conducted. By adopting the slow-freezing method and combining macro-structure and micro-morphology, the damage mechanism and the deterioration law of fiber-reinforced SSC under seawater freezing and thawing were investigated. The results indicate that, macroscopically, the incorporation of GF and PVA can effectively mitigate the damage to the matrix and reduce the effects of external erosive substances on the rate of strength loss, the rate of mass loss, and the relative dynamic elastic modulus. After 75 cycles, the SSC with a total volume doping of 0.3% and a blending ratio of 1:1 showed a 41.23% and 27.55% reduction in mass loss and strength loss, respectively, and a 29.9% improvement in relative dynamic elastic modulus compared with the basic group. Microscopic analysis reveals that the combined effect of freezing and expansion forces, the expansive substances generated by seawater intrusion into the interior of the matrix, and salt crystallization all weaken the bond between aggregate and mortar, leading to accelerated deterioration of the concrete. The incorporation of fibers enables the matrix to become denser and improves its crack-resistant properties, resulting in a better durability than that of the basic group. The damage prediction model established by the NSGM(1,N) model of gray system theory exhibits high accuracy and is suitable for long-term prediction, accurately predicting the damage of seawater sea sand concrete under seawater freeze–thaw coupling. [ABSTRACT FROM AUTHOR]

The use of metal-coated ceramic powders not only effectively enhances the wettability of the metal–ceramic interface but also promotes a more uniform microstructure in Ti(C,N)-based cermets, which is advantageous for improving their mechanical properties. In this study, ultrafine Co- and Ni-coated (Ti,W,Mo,Ta)(C,N) powders were synthesized via the spray-drying-in-situ carbothermal reduction method. Subsequently, Ti(C,N)-based cermets were effectively fabricated using the as-prepared ultrafine Co- and Ni-coated (Ti,W,Mo,Ta)(C,N) powders. The impact of reaction temperature, heating rate, and isothermal time on the phase and microstructure of prepared powders was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Additionally, the microstructure of the as-sintered cermets was experimentally investigated. The findings reveal that the complete reduction of Co and Ni metal salts, pre-coated on the surface of (Ti,W,Mo,Ta)(C,N) particles, can be achieved through rapid heating (10 °C/min) in a specific temperature range (600–1000 °C) with an isothermal time of 3 h at a lower reduction temperature (1000 °C). The synthesized powders have only two phases: the (Ti,W,Mo,Ta)(C,N) phase and Co/Ni phase, and no other heterogeneous phases were observed with an oxygen content of 0.261 wt.%. Notably, the conventional core–rim structure was not dominant in the cermets obtained from the prepared Co- and Ni-coated (Ti,W,Mo,Ta)(C,N) powders. Moreover, the heterogeneous segregation effect of the Co/Ni coating on the ultrafine powder particles resulted in a finer microstructure than the traditional cermets with the same composition. However, the grain size is mainly in the range of 0.5–0.8 μm. The weaker residual stresses at the core and rim interfaces and the finer particle distributions could theoretically enhance the toughness of Ti(C,N)-based cermets, simultaneously. [ABSTRACT FROM AUTHOR]

As a countermeasure to the problem of brittleness of seawater sea sand concrete (SSC), volumetric admixture of glass fiber (GF) and polyvinyl alcohol (PVA) fiber was used as variable, the corresponding specimens were prepared, and the cube compressive strength, splitting tensile strength, axial compressive strength, and elastic modulus were tested. The microstructure of fiber reinforced seawater sea sand concrete was analyzed by scanning electron microscope (SEM) scanning and energy dispersive spectroscopy (EDS) dot scanning, and a model was established based on the grey system theory. The research results show that the fiber can effectively reduce the formation of cracks, leading to a ductile failure of the specimen. In general, the mechanical properties of mixed fiber were improved better than that of single fiber, and the hybrid ratio 2:1 brings a improvement of 24. 2% and 38. 8% for the compressive strength and splitting tensile strength, respectively. The hybrid ratio of 1:1 increases the axial compressive strength and elastic modulus by 34. 5% and 15. 5%. It was observed by SEM and EDS that fiber incorporation could densify the matrix, while the main disadvantage of SSC was that the salt crystallization generated by corrosive ions and swelling substances weakened the bond between aggregate and mortar, resulting in defects of interfacial transition zone (ITZ) . The established NSGM(1, 3) model has a high accuracy, the accuracy reaches class II and conforms to the long-term prediction, which provides a favorable basis for the study of the strength evolution of fiber reinforced seawater sea sand concrete. [ABSTRACT FROM AUTHOR]

• The microstructure of Mg-Al-Sn-RE anode is tailored via friction stir processing. • The processed anode has fine grains, low dislocation density, and weak orientation. • This unique anode structure boosts the voltages and capacities of Mg-air battery. • The discharge mechanism corresponding to the unique anode structure is analysed. Constructing the magnesium alloy with fine grains, low density of dislocations, and weak crystal orientation is of crucial importance to enhance its comprehensive performance as the anode for Mg-air battery. However, this unique microstructure can hardly be achieved with conventional plastic deformation such as rolling or extrusion. Herein, we tailor the microstructure of Mg-Al-Sn-RE alloy by using the friction stir processing, which obviously refines the grains without increasing dislocation density or strengthening crystal orientation. The Mg-air battery with the processed Mg-Al-Sn-RE alloy as the anode exhibits higher discharge voltages and capacities than that employing the untreated anode. Furthermore, the impact of friction stir processing on the electrochemical discharge behaviour of Mg-Al-Sn-RE anode and the corresponding mechanism are also analysed according to microstructure characterization and electrochemical response. [ABSTRACT FROM AUTHOR]

The lack of a suitable rootstock to control scion growth has limited the development of high-density plantations in pear production, which is partly attributed to poor understanding of the dwarfing mechanism. In the present study, the rootstock of the dwarf-type pear (Pyrus betulaefolia) 'PY-9' was identified and used as the material for anatomical analysis. 'PY-9' grew to half the tree height of the normal cultivar 'Zhengdu', along with fewer internodes and shorter length. Significant differences in growth rate between 'PY-9' and 'Zhengdu' were detected at approximately 30 days after full bloom, which corresponded with the time of the greatest difference in water potential between the dwarf and normal cultivar. 'PY-9' showed a higher photosynthetic rate than 'Zhengdu'. Anatomical analysis showed that 'PY-9' had higher area ratios of both phloem and xylem and more developed vascular tissues than 'Zhengdu'. The three-dimensional reconstructed skeleton of the xylem from X-ray computed tomography scanning revealed greater intervessel connectivity in 'Zhengdu' than in 'PY-9', which could contribute to the more vigorous growth of 'Zhengdu'. This study thus provides the first comparison of the microstructural properties of xylem elements between a dwarfing-type and vigorous-type pear rootstock, providing new insights into the dwarfing mechanism in pear and facilitating breeding of dwarf pear rootstocks to increase crop productivity. [ABSTRACT FROM AUTHOR]

In this study, graphene oxide (GO) was prepared by an improved Hummers’ method, and the graphene oxide–carbon fiber (GO-CF) hybrid fibers were prepared by electrophoretic deposition (EPD) with the above GO. The microstructure and mechanical properties of GO, CF and GO-CF cement matrix composites were studied by X-ray diffraction (XRD), SEM and mechanical tests. X-ray diffraction (XRD) and SEM results showed that the surface modification of CF with GO could effectively improve the dispersion of CF in the cement matrix, the template action of GO providing nucleation sites for cement hydration, which significantly enhanced the interface bond between CF and the cement matrix. The mechanical properties test results showed that the early compressive strength and flexural strength of cement matrix composites were significantly improved by GO. Adding CF into the cement matrix significantly improved the flexural strength, although the compressive strength was not improved, even exhibiting a downward trend when the CF content exceeded 0.5%. The flexural and compressive strength of GO-CF cement matrix composites were clearly improved, its 7 d flexural strength and compressive strength increased by 30.89% and 17.56%, respectively, and its 28 d flexural strength and compressive strength increased by 38.37% and 14.32%, respectively. The research results indicate that a new method was provided which used GO as a dispersant and surface modifier to improve the dispersion of chopped CF in a cement matrix, and the interaction between CF and the cement matrix interface could also be applied to the functional aspects of cement matrix composites.

Ti15Mo alloy has been regarded as one of the most potential biomedical materials due to its excellent performance. However, the low hardness and poor wear resistance of titanium alloy limit the further application. Therefore, high temperature solid carburising technology was performed on the surface of Ti15Mo alloys to prepare titanium carbide (TiC) coating with graphene (G) as the carburising agent. The microstructure, mechanical properties, and tribological properties of TiC coating under different lubricants were investigated. Results showed that TiC coating was closely bonded to the titanium substrate. The maximum thickness of TiC coating treated with 1150°C was approximately 184.02 μm, and the microhardness of alloys treated with 1100°C can achieve 1221.5 HV. All modified Ti15Mo alloys showed improved tribological performance compared to the original samples. The wear mechanisms of modified Ti15Mo alloys were abrasive wear and adhesive wear under the SBF lubricant, and the TiC coating was slightly peeled off. The overall friction coefficient and wear rate under 25% calf serum lubricant were lower than the SBF lubricant, and surface scratches were almost absent, and slight abrasive wear and adhesive wear occurred on the surface. [ABSTRACT FROM AUTHOR]

This paper aims to study the relationship between the microstructure and the mechanical properties of X70 submarine pipeline steel with 40.5 mm thickness. The microstructure was examined by using optical microscopy, scanning electron microscopy and an electron backscattered diffractometer, while the mechanical properties were examined by using a hardness test, a tensile test, a Charpy impact test and a drop weight tear test (DWTT), respectively. The results show that the base metal (BM) of the pipe has a low yield ratio of 0.83 and an excellent elongation of more than 45%. The DWTT shear area of the steel plate reaches 87%, showing excellent low-temperature toughness. The Charpy impact energy increases when the distance from the fusion line increases, and it reaches a maximum at the BM near the heat-affected zone (HAZ) due to the small martensite-austenite (MA) constituents and fine grains. The concentrated distribution of blocky/slender MA constituents along the prior austenite grain boundaries of the intercritically reheated coarse-grained HAZ and the large MA constituents are the main reasons for the deteriorating impact toughness. Delamination cracks in the DWTT fracture surface only occurred in the midthickness of a sample with a small opening width that spread about 2.1 mm perpendicular to the DWTT fracture surface and were finally arrested at the acicular ferrite clusters containing a high density of high-angle boundaries.

In order to obtain films with better mechanical properties and fracture toughness, the (TiAlCrZrNb)- Six-N (x=0, 4%, 8%, 12% and 16%) high entropy ceramic nanocomposite films with different Si contents were deposited on Si substrate by magnetron sputtering technology. The effects of Si doping on the microstructure, mechanical properties! and fracture toughness of the films were investigated by X-ray diffractometry, scanning electron microscopy, high-resolution transmission electron microscopy and Nano indentation apparatus. The results show that the mechanical properties and fracture toughness of the films increase first and then decrease with the addition of Si element, which can be attributed to the formation of nanocomposite structures. When Si content is 4%, (TiAlCrZrNb)-Six-N film has the best comprehensive mechanical properties, and Us maximum hardness and elastic modulus are 22.7 GPa and 192.0 GPa, respectively. In this case, the fracture toughness reaches the best, and the radial crack length C as 6.760 µm, The K1C was 1.77 MPa • m1/2. [ABSTRACT FROM AUTHOR]

Molecular dynamics is a method of studying microstructure and properties by calculating and simulating the movement and interaction of molecules. The molecular dynamics simulation method has become an important method for studying the structural and dynamic characteristics of slag systems and can make up for the shortcomings of existing detection methods and experiments. Firstly, this paper analyzes the development process and application fields of molecular dynamics, summarizes the general simulation steps and software algorithms of molecular dynamics simulation methods, and discusses the advantages and disadvantages of the algorithms and the common functions of the software. Secondly, the research status and application progress of molecular dynamics simulation methods in the study of phosphate, silicate, aluminate and aluminosilicate are introduced. On this basis, a method of combining molecular dynamics simulation with laboratory experiments is proposed, which will help obtain more accurate simulation results. This review provides theoretical guidance and a technical framework for the effective analysis of the microstructure of different slag systems via molecular dynamics, so as to finally meet the needs of iron and steel enterprises in producing high-quality steel grades. [ABSTRACT FROM AUTHOR]

Reactive sintering has been widely utilized to densify ceramics. Although the technology has numerous advantages, the composition of as-sintered ceramics is hard to be adjusted unless additional products are added. In this work, a novel solid-state route based on the reactions among TiN, Al and B were proposed to consolidate TiB 2 -AlN- h BN ceramics (TAB) with tunable compositions (h BN ≤ 42 vol%, AlN ≤ 45 vol%). Dense TAB with high relative density, refined grain size and homogeneous microstructure were obtained via spark plasma sintering at 1800 °C and 60 MPa. It was found that exothermic reactions between the reactants could be ignited during heating, and the order of temperature at which the combustion process occurred was just opposite to the sequence of adiabatic temperature for individual reactions. Effects of h BN and AlN amounts on the densification, microstructure, mechanical properties, machinability and electrical resistivity of as-sintered ceramics were comprehensively investigated. Compared to AlN, h BN content played a more obvious role on those properties. As h BN contents increased from 0 to 42 vol%, the flexural strength, fracture toughness, Vickers hardness and modulus of TAB continuously decreased. TAB with h BN amounts ≥ 13 vol% exhibited better machinability with surface roughness lower than 2.9 µm after machining. Nevertheless, their electrical resistivity values at room temperature fluctuated in a narrow range between 43 μΩ·cm and 83 μΩ·cm, irrelevant with the h BN amounts. • TiB 2 -AlN- h BN ceramics with tunable compositions were reactively densified without adding external h BN or AlN at reduced temperature. • Relationships between the adiabatic temperature and the temperature when reactions occurred in the TiN-Al-B system were investigated. • TiB 2 -AlN- h BN ceramics with synergistically improved mechanical, electrical and machinability were achieved. [ABSTRACT FROM AUTHOR]

The corrosion resistance of FeCoNiCr high-entropy alloy deposits was investigated upon being prepared by current electrodeposition. The coatings were co-deposited in an electrolyte of an aqueous ferrous, cobalt, nickel, and chromium sulfates solution. Energy dispersive spectrometry analysis demonstrated that all four elements were co-deposited successfully. At the same time, the results from SEM indicate that the surface of the coating exhibits a granular morphology, with uniform density and no presence of cracks, with sizes ranging from 500 nm to 5 μm. Furthermore, X-ray diffraction patterns enunciated that the as-deposited coatings were amorphous. The polarization curves of the FeCoNiCr high-entropy alloy coating were measured by an electrochemical workstation in 3.5 wt.% NaCl, 1 mol·L−1 H2SO4 and 1 mol·L−1 NaOH solutions. The results revealed that the coating exhibited excellent corrosion resistance. The corrosion mechanism of the FeCoNiCr high-entropy alloy coating was analyzed in different environments. Moreover, the scratch testing method was employed to determine the alloy adhesion on the substrate, with higher values obtained for the FeCoNiCr alloy. [ABSTRACT FROM AUTHOR]

Optimizing alloy composition is an effective way to improve the microstructure and properties of superalloys. Herein, the influence of carbon content (0.071, 0.105, and 0.136 wt%, respectively) on the microstructure and mechanical properties of GH3230 alloy formed by laser melting deposition is investigated. The results indicate that the carbon contents affect the quantity, morphology, and distribution of carbides in the matrix of the alloy. As the carbon content increases, the number of carbides increases, and the morphology of the carbides at the grain boundaries changes from discontinuous blocks to chains, and finally into strips. Three alloys with high plasticity at room temperature, and the maximum elongation close to 60% is achieved for alloy containing 0.105 wt% C. The high‐temperature elongation of the alloy also increases at first and then decreases with the carbon. It is therefore concludes that the optimized carbon content is 0.105 wt% by combining both the strength and plasticity for GH3230 alloy prepared by laser melting deposition. [ABSTRACT FROM AUTHOR]

The effects of whey protein isolate (WPI)‐pectin pre‐emulsified vegetable oil on the physicochemical properties and microstructure of low‐fat yogurt (LFY) were investigated by particle size distribution, water‐holding capacity (WHC), texture, rheology, electron microscopy, storage stability, and sensory analysis. The vegetable oil was pre‐emulsified into two types of emulsions, a mixed emulsion (ME: WPI‐pectin complexes were adsorbed directly at the interface) and a bilayer emulsion (BE: Pectin was added to a previously established WPI‐stabilized interface). The results showed that yogurts added with pre‐emulsified vegetable oil (ME‐Y, BE‐Y) had significantly better quality than LFY, with better WHC, textural properties, rheological properties, and storage stability. The average particle size of ME (11.96 µm) was larger than that of BE (10.23 µm). The consistency of yogurt added with ME (ME‐Y) was significantly higher than that of yogurt added with BE (BE‐Y), at 2359.10 and 2181.12 g s, respectively. Meanwhile, ME‐Y exhibited storage stability similar to full‐fat control (FFY) and higher sensory scores. Interestingly, the WHC of BE‐Y (49.03%) was higher than that of ME‐Y (45.63%). In addition, WPI + Pectin‐Y exhibited higher WHC (53.81%) and consistency (2518.73 g s) compared to ME‐Y and BE‐Y, but the particle size distribution was not uniform, and the direct addition of WPI, pectin, and oil had no positive effect on improving the rheological properties of yogurt. Overall, the addition of WPI‐pectin pre‐emulsified vegetable oil improved the quality of LFY. These findings are particularly relevant for the production of higher quality LFY. [ABSTRACT FROM AUTHOR]

In order to create the components of cermet tool material, a new method for designing tool material based on wear prediction was proposed. The finite element simulation of the cutting process was carried out based on a previously constructed microstructure model of the tool material which involves the components and its volume fractions. A new Ti(C7, N3)/TiB2/WC was designed and prepared based on the acquisition of variations in tool wear morphology among different components and the wear prediction results were verified by the high-speed cutting experiment of stainless steel 06Cr19Ni10. It has been shown that with 20% TiB2 and 15% WC, respectively, the changes of the peak temperature of the rake face and the cutting force reached the lowest level and also the wear amount of the tool was the minimum. With a sintering temperature of 1550 °C, a pressure of 32 MPa and a holding time of 30 min, the bending strength of the Ti(C7, N3)/TiB2/WC cermet tool and hardness were 1096.45 MPa and 18.9 GPa, respectively, and the fracture toughness was 9.85 MPa∙m1/2. The validity of the proposed wear prediction model was verified by studying the variation of the wear amount and the main wear area of the developed tool. This research provides a new efficient method for the design of cermet tool materials, which is time-saving and cost-effective. [ABSTRACT FROM AUTHOR]