Effect of temperature and Rhenium content in precipitates on dispersion hardening of tungsten

Tungsten (W) is being developed as a plasma-facing material for fusion reactors, where it is subjected to MeV neutron irradiation, low-energy helium isotope particles, and high temperatures. These conditions lead to the formation of point defects, dislocation loops, voids, and transmutation into rhenium (Re) and osmium (Os), which form precipitates that significantly impact dislocation motion and increase hardness. This study uses molecular dynamics modeling to examine the interaction between an edge dislocation and Re-rich particles of various stoichiometries, specifically coherent bcc-phase particles and noncoherent s-phase precipitates. Results show that shear stress increases by approximately 20e40 % with larger particle size (3e5 nm diameter) and higher Re content (50e75 at.%), while temperature (600e1400 K) has a weak effect on critical shear stress. Coherent bcc-phase particles are weak barriers to dislocations, whereas noncoherent s-phase precipitates are strong obstacles. The study reveals that dislocations typically cut through these particles, except for noncoherent spherical ones, which are bypassed via the Orowan mechanism.