The mechanical behavior of pure Pt at elevated temperatures is critical for its high-temperature processing and applications. To understand its thermal deformation behavior and reach better processing control, thermal compression deformation was conducted for pure Pt in this work with a strain rate of 0.01 s−1 and temperatures ranging from 500 to 700 °C, followed by microstructure characterization by using electron backscatter diffraction (EBSD) technique. The results indicate that the grain size, fraction of low-angle grain boundaries, and dislocation density are generally reduced with increasing temperature. An analysis combining true stress–strain curves and microstructural characteristics indicates that dynamic recovery based on dislocation cross-slip/climb is always a main softening mechanism of pure Pt during thermal deformation. Continuous dynamic recrystallization and geometric dynamic recrystallization also occur when the deformation temperature exceeds 650 °C, which will effectively improve the microstructural homogeneity of pure Pt.

Molybdenum alloys are promising materials for high-temperature gas-cooled reactor fuel cladding due to their excellent performance at elevated temperatures, favorable mechanical properties, corrosion resistance, and low neutron absorption cross-section. However, their high melting point and inherent hardness require annealing to improve processability. This study investigates the effects of vacuum annealing on the microstructure and texture evolution of rotary swaged Mo-Re alloys. The as-swaged alloy exhibits a fibrous structure with elongated grains along the axial direction (AD). Annealing at 1200 degrees C results in a bimodal microstructure, with both deformed and recrystallized grains, indicating a partially recrystallized (PRX) state. Furthermore, annealing at 1300 degrees C leads to a completely recrystallized (CRX) microstructure. The recrystallization mechanism is primarily driven by sub- grains coalescence. The texture of the rotary swaged Mo-Re alloy is dominated by a strong (101 )//AD fiber texture, accompanied by a weaker (001 )//AD texture. After recrystallization, the intensity of the <101>//AD texture decreases, while the <001>//AD texture becomes more prominent. These texture changes suggest that the <001>//AD texture promotes recrystallization, whereas the <101>//AD texture hinders it. The evolution of the recrystallization texture is attributed to the preferential growth of <001>//AD grains and stress-driven grain rotation. These findings provide valuable insights for optimizing the heat treatment process of rotary swaged Mo-Re alloys.

The structure and elastic properties of alpha-Zr and its hydrides were investigated by first-principle calculations and experimental methods. Considering all possible H-atom configurations, different phase models of hydrides were constructed. Results show that the stable structures of gamma, delta and epsilon hydrides are P4(2)/mmc, P4(2)/nnm and I4/mmm, respectively. Calculation results suggest that epsilon hydride has the lowest formation enthalpy, and the phase transition sequence of gamma -> delta -> epsilon is proposed. Compared with those of alpha-Zr, the c-axis lattice constants of hydrides become smaller, and the expansion volumes of gamma, delta and epsilon unit cell are 12.1%, 14.8% and 17.9%, respectively. The calculated elastic modulus (E) of the three hydrides are lower than that of alpha-Zr, but their elastic anisotropy is higher than that of alpha-Zr. The elastic properties of alpha-Zr matrix and delta hydride were analyzed by nanoindentation experiment and the results show that E of the alpha-Zr matrix and d hydride is 116.88 and 111.01 GPa, respectively. Therefore, the stress concentration is easy to occur on the hydride sides near the hydrides/matrix interface, so the hydrides are more likely to be the sources of crack and cause brittle fracture of zirconium alloys.

First-principles can effectively predict the stability of crystal structures, but it is still difficult in designing Zr-Ti binary base alloys directly. In this work, an effective approach based on the first-principles calculations and experiments was putting forward to predict the phase of Zr-Ti binary base ZrTiAlV alloys. Two physical parameters (cohesive energy, EC, and effective valence electron, EVE) were selected to evaluate the β-phase stability which deeply affected the microstructure of ZrTiAlV alloys. In the [[EQUATION]]-[[EQUATION]] diagram, microstructures of the ZrTiAlV alloys were separated into B2, β, α+β and α phase regions. Validity of the prediction of the phase was verified by joint use of the differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). And with aid of [[EQUATION]]-[[EQUATION]] diagram the microstructure of ZrTiAlV alloys can be predicted accurately. This approach provides a method for designing ZrTi binary base ZrTiAlV alloy, and other binary base alloy and even high entropy alloy.

In this study, the interface structures and adhesion behaviour between the Cr coating and Zr cladding tube substrate were studied using experimental and first-principles methods. The microstructure of the coating -substrate interface was characterised using electron backscattered diffraction (EBSD), backscattered electron, scanning electron microscopy, and transmission electron microscopy. The atomic structure of the Cr/Zr interface was evaluated using the first-principles calculations. The adhesion performance of the Cr/Zr interface was assessed based on the calculations and experimental results. Two orientation relationships, between the Cr coating and Zr cladding tube, Cr(0 0 1)/Zr(0001) and Cr(0 0 1)/Zr(01(1)over bar0) were observed using EBSD. These were in the radial direction of the Zr cladding, with the Cr(0 0 1)/Zr(0001) interface having a greater bonding strength than the Cr(0 0 1)/Zr(01(1)over bar0) interface. Additionally, a diffusion layer approximately 50 nm thick, including a mixed crystal region approximately 5 nm thick at the Cr/Zr interface, was observed. The first-principles calcu-lations attributed the strong atomic bonding strength at the Cr/Zr interface to the joint influence of covalent and ionic bonds. The Cr atoms exhibited metallic bond characteristics, while the Zr atoms exhibited covalent bond characteristics.

In this study, a Ti-33Zr-12Al-6V alloy was prepared, and its work hardening and softening mechanisms were investigated via tensile tests conducted at room temperature. The interaction between the dislocations and strain induced martensite (SIM) results in work hardening; whereas, the shearing of the grain boundaries by the dislocations for entering the adjacent grains results in work softening, which occurs when the logarithmic strains is between 5.8% and 7.6%. Work softening weakened the effect of work hardening; however, through work softening, the workability, which is insufficient in high-strength beta-phase titanium alloys, was significantly increased. The microstructure evolution of Ti-33Zr-12Al-6V alloy under different strains was investigated using the quasi in-situ electron backscatter diffraction and scanning electron microscopy methods during the aforementioned tensile tests. The microstructure near the shear bands was observed via transmission electron microscopy using a focused ion beam. First, the {112}< 111 > slip systems with a high Schmid factor (SF) (>0.25) were activated and, subsequently, the {112}< 111 > with a low SF (<= 0.25) and {011}< 111 > slip systems were activated in most grains during tensile deformation.

Plastic deformation at room temperature, and the proceeding heat treatments, are important processes for optimizing the microstructure and mechanical properties of austenitic stainless steel. The microstructure and mechanical properties of cold-drawn 304 austenitic stainless steel wire were investigated after annealing at 700 °C and 800 °C, with different times (20, 40 and 60 min) and drawing strain (0.4, 1.0 and 1.5). Electron backscattered diffraction (EBSD) techniques, transmission electron microscope (TEM) analysis, differential scanning calorimeter (DSC) and tensile tests were performed in order to study the microstructure evolution and mechanical properties during different annealing processes for the 304 austenitic stainless steel wire. The results showed that the quantity of α ′ martensite and dislocations increased with an increase in the strain, which means that, while the ultimate tensile strength of the cold-drawn wires elevated, the elongation reduced. The mechanical properties of stainless steel wires also varied with the evolution of martensite transformation characteristics, density of stacking fault, dislocation and twin, as well as the recrystallization degree under various annealing conditions. The recrystallization temperature of steel wire was mainly determined by the magnitude of the strain, while the martensite reversal temperature was determined by the stacking fault energy and the deformation value. The temperature of recrystallization and martensite reverse in steel wire decreased with the increment of the strain. The balance of tensile strength and elongation of steel wire can be obtained by adopting the proper annealing process combined with cold-drawing deformation. In this paper, we showed that a good combination of strength and elongation in 304 austenitic stainless steel can be obtained with a strain of 1.5 annealed at 800 °C for 20 min.

Zr alloy has been gradually developed and applied in nuclear industry, aerospace, biomedicine and other fields, just for its excellent characteristics, such as high hardness, high melting point, low thermal expansion coefficient, corrosion resistance and low thermal neutron absorption cross section. In this paper, the Zr alloys research status of composition design methods, including empirical/semi-empirical method, first-principles calculation method, d-electron orbital method and CALPHAD method, are introduced. The research methods and current situation of Zr alloy involved in first-principles calculation are mainly introduced. With the aid of the alloy design model and computer operation, the relationship between the mechanical behavior and microstructure of materials can be effectively and systematically understood, providing a theoretical basis for alloy composition design. Combined with the research progress and achievements of Zr alloy design methods, the research and development trend of Zr alloy design is briefly discussed.

Phase stability and the elastic properties of α, β, α" and ω phases in four different component TiZrAlV alloys were studied by first-principles calculations and experiments. The results of Differential Scanning Calorimetry (DSC) and X-ray Diffractometer (XRD) showed that α, β, α" and ω phases could be stabilized in four alloys except β phase in TZA8 alloy. Varied compositions and phases in the alloys lead to different Young’s modulus E. First-principles calculations were used to verify the experimental results in the four TiZrAlV alloys. Four atomic configurations of TiZrAlV systems with β, α", α and ω phases were obtained using approximate simplified atomic ratios. These 16 models were calculated to investigate their phase stabilities and elastic properties by means of electronic structure, formation enthalpy ΔHf and elastic properties. The density of states (DOS) of β phase in TZA8 alloy without pseudogap near Fermi level (EF) suggested that β phase was unlikely to exist in the TZA8 alloy, which agreed with the experiment results. From the results of energy calculations, β-phase was found to be more structurally stable compared to α, α" and ω phases in TZA12V6 and TZA12V4 alloys. α"-phase in alloys TZA14V8, TZA12V6 and TZA12V4 and β-phase in TZA8 alloy had the lowest stability. The results of elastic properties showed that Young’s modulus was affected by alloy composition and phase, and β-phase had the characteristics of lower Young’s modulus and better plasticity than other phases in the TiZrAlV alloys. The results of experiments and first-principles calculations manifested that the compositions affected the phase stabilities and the elastic properties of the TiZrAlV alloys.