In order to obtain the effect of W and Hf elements on the mechanical properties of Ta–W–Hf alloys, the structural, mechanical, and electronic properties of Ta–xW–6.25Hf (x = 6.25, 12.50, 18.75, 25.00, 31.25, 50.00) alloys were studied using first-principles calculation based on density functional theory, and the supercell method. The calculated formation enthalpy and elastic constants clarify that Ta–W–Hf alloys have structural and dynamical stability. The formation enthalpy and the cohesive energy decrease with the increase in W content, and the cohesive energy increases when Hf element is added to Ta–W alloy. In addition, bulk modulus (B), shear modulus (G), and Young’s modulus (E) for each of the Ta–xW alloys increase gradually with the increase in W concentration. The B, G, and E of Ta–xW–6.25Hf alloys is lower than that of Ta–xW alloy under the same W content conditions, suggesting that Hf alloying with higher Ta–W concentration becomes softer than the Ta–W alloy. Based on the mechanical characteristic, the B/G and Poisson’s ratio of Ta–W–Hf alloys are higher than those of Ta–W alloys with W content over 25%, the ductility of Ta–W–Hf alloys improves with the addition of Hf, and Hf can reduce the anisotropy of Ta–W–Hf alloys. Furthermore, the electronic density of states shows that alloying W and Hf improves the metallicity of Ta. The results in this work provide the underlying insights needed to guide the design of Ta–W–Hf alloys with excellent mechanical properties.

Using additive friction stir deposition (AFSD), the poor weldability of 1045 steel can be solved, facilitating the efficient and high-performance additive manufacturing of its components. This study selected spherical 1045 steel powder and investigated key factors influencing mechanical properties, including deposition temperature, tool rotational rate, and axial force. The results showed that dynamic recrystallization (DRX) occurred in AFSD 1045 steel, which produced randomly oriented fine equiaxed grains with a size range of 1–3 µm and was sensitive to changes in tool rotational rate and axial force. The AFSD 1045 steel, with a maximum surface hardness of 477.2 HV, ultimate tensile strength of 1061.9–1172.3 MPa, and elongation of 8.6–19.0%, has superior overall mechanical properties compared with other forming processes. Moreover, by analyzing tensile fracture morphology, geometrically necessary dislocation (GND) density, and coincidence site lattice (CSL) boundary distribution characteristics, the strengthening mechanism in AFSD 1045 steel was discussed. The research findings serve as a reference for optimizing the AFSD process for 1045 steel and supply a new alternative for joining and manufacturing this material.

This study aims to examine the variation in corrosion characteristics and tensile properties of WE43 magnesium alloy in an actual marine atmospheric environment by means of outdoor exposure tests. The macroscopic corrosion morphology, microstructure, and tensile properties were analyzed. The results indicated that WE43 alloy will corrode rapidly during exposure under marine atmospheric environmental conditions, resulting in a loose and porous Mg(OH)₂ layer on the surface. The Mg matrix was mainly consumed as an anode, leading to the occurrence of corrosion pits. With the increase in exposure time, both the tensile strength and plasticity of WE43 alloy gradually deteriorated. After exposure for six months, the elongation and area reduction were significantly reduced, with a reduction ratio of more than 50%. After 18 months of exposure, the ultimate strength of the alloy decreased from 359 MPa to 300 MPa. According to an analysis of fractures in the alloy, the corrosion pits on the sample surface were the main reason for the decrease in tensile properties.

In this study, we employed the first-principles method based on density functional theory to calculate the elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and density of states for both cubic and tetragonal phases of Pb(Zr_xTi_1−x)O₃. The structural model of Pb(Zr_xTi_1−x)O₃ was established using the virtual crystal approximation (VCA). Our results demonstrate that the VCA-calculated properties are in excellent agreement with other theoretical predictions and experimental data. As the Zr content increases, the lattice constants of both cubic and tetragonal Pb(Zr_xTi_1−x)O₃ increase, while the c/a ratio initially decreases and subsequently increases. Both cubic and tetragonal Pb(Zr_xTi_1−x)O₃ satisfy the Born stability criteria, indicating mechanical stability. For the cubic phase, the elastic constants, bulk modulus, and shear modulus decrease with increasing Zr content. In contrast, for the tetragonal phase, the elastic and shear moduli exhibit a non-monotonic trend, peaking at a Zr content of 0.5, where Pb(Zr_0.5Ti_0.5)O₃ demonstrates superior mechanical properties. A comparative analysis reveals that as Zr content increases, the cubic phase exhibits enhanced structural resilience, greater electronic structure stability, and increased anisotropy. These characteristics make cubic Pb(Zr_xTi_1−x)O₃ more suitable for advanced manufacturing techniques such as additive manufacturing, offering enhanced design flexibility for ferroelectric materials.