Ab-initio investigation of mechanical and fracture-related properties of W-Re σ and χ precipitates

Abstract

Tungsten (W) is a leading candidate for plasma-facing materials in fusion reactors. Recently, experiments have shown that during neutron irradiation, W and its transmutation products, mainly rhenium (Re), will form precipitates of the σ and χ types. This study identifies close-packed planes of the σ- and χ-phases in the W-Re system and uses ab-initio methods to identify mechanical properties such as elastic constants, generalized stacking fault energies (GSFE), and fracture toughness associated with brittle and ductile mechanisms. By utilizing a sublattice model we demonstrate how these properties depend on the Re content. For Re concentrations in the range where the σ- and χ-phases are stable, we find a weak dependency on the Re content, meaning that the elemental composition has little influence on the mechanical and fracture-related properties.