Microstructure and mechanical properties of low activation Fe-Ti-Cr-V-W multi-principal element alloys

Single-phase multi-principal element alloys can have low activation and rapid induced radioactive decay properties that make them ideal structural materials for the first wall/cladding structure of nuclear fusion reactors. The present work proposes the design of multi-principal element alloys consisting of low activation elements Fe, Ti, Cr, V, and W with both equiatomic and optimized compositions. The optimal composition of the multiple components is based on the formation of a single-phase solid solution with a minimal Gibbs free energy. The microstructures and mechanical properties of the alloys are investigated. The equiatomic alloy is observed to be composed of dendritic crystals consisting of a body-centered cubic (bcc) solid solution phase and a complex intermetallic compound, while the optimized alloy is composed of cellular dendritic crystals consisting of a single bcc solid solution phase in its as-cast state. Homogenization treatment is observed to reduce the fracture strength of the equiatomic alloy due to grain coarsening, although it has little effect on the hardness and other mechanical properties. However, homogenization increased the hardness and compressive yield strength of the optimized alloy to different degrees. The optimized alloy has better plastic toughness than the equiatomic alloy, which increases its workability and radiation resistance. (c) 2020 Elsevier B.V. All rights reserved.