High-temperature creep properties and mechanisms of Mo-Re alloys

Abstract

Due to their excellent high-temperature mechanical properties and good room-temperature machinability, molybdenum‑rhenium (MoRe) alloys have been widely used as high-temperature structural materials. This study investigates the creep properties of the MoRe alloys prepared by powder metallurgy with the Re contents of 5, 14, and 41 wt%. The results showed that the steady-state creep rates of Mo5Re, Mo14Re, and Mo41Re under creep conditions of 1350 K and 100 MPa were 2.21 × 10⁻⁷ /s, 1.58 × 10⁻⁷ /s, and 8.14 × 10⁻⁸ /s, respectively. It is revealed that the creep resistance increases with Re content. The changes in the proportions of the slip systems in MoRe alloys before and after creep were analyzed. The results show that the proportion of {112}〈111〉 or {123}<111 > slip systems rises with increasing Re content. DFT results indicate that the unstable stacking fault energy of slip systems decreases with the increase of Re content, which implies that the activation energy barrier of slip systems decreases with the increase of Re content. This result indicates that the increase of Re content promotes the activation of multiple slip systems. The activation of multiple slip systems enables the high-temperature deformation capacity of MoRe alloys to improve with increasing Re content. Grain state and dislocation morphology evolution demonstrate that increased Re content suppresses dislocation climb behavior in MoRe alloys. Additionally, in Mo41Re, a small number of Re atoms aggregate to form Re clusters. The interaction between these Re clusters and dislocations further restricts dislocation migration. These factors collectively contribute to the improvement of creep resistance in MoRe alloys with increasing Re content.