Effect of transmutation rhenium on tensile properties of tungsten by molecular dynamics simulation

Abstract

The tensile properties of W-Re alloys are studied using molecular dynamics method. Two forms of transmutation Re uniform distribution and cluster distribution in W-Re alloys are systematically explored, W-xRe alloys and W-nRe clusters, respectively. The effects of Re concentration, Re cluster number density, and temperature on the tensile properties are discussed. Findings suggest that Young’s modulus of W-xRe alloys decreases with increasing Re concentration, reaching only 323 GPa when the Re concentration is 50 at.%. The ultimate stress of W-xRe alloys is lower than that of pure tungsten, indicating that the presence of Re would accelerates the fracture of W-xRe alloys. Additionally, Re clusters of different sizes and number density are constructed in tungsten, forming the W-nRe cluster system. Interestingly Re clusters can reduce tensile strength, and the strain hardening modulus (E sh) is independent of the single Re cluster size. With an increase in Re cluster number density, Young’s modulus, ultimate stress, and ultimate strain decrease gradually, leading to fracture in the Re cluster position. Non-coherent and semi-coherent interfaces between Re cluster (χ- and σ-phases) and W lattice cause Re cluster to undergo imbalance stress. For example, in W-12.5 at.% Re alloys, stress–strain curves are studied at different temperatures, revealing that Young’s modulus decreases with increasing temperature, reaching 292 GPa at 1300 K. A linear formula is obtained by fitting Young’s modulus-temperature curve. These results provide important theoretical references for the design of W-Re alloys as the PFMs in the ITER.