Multicomponent Alloy of FeCoNiVTiAl with a Dual Core–Shell Structure and Cactus-Like Morphology for Aerospace Applications

A dual core–shell structure with cactus-like morphology in a FeCoNiVTiAl multiprincipal element alloy was synthesized for the first time through a reasonable composition design, which is used as a candidate for aerospace applications. The morphology evolution of this core–shell structure and its response to mechanical properties with the Ti/Al ratio were characterized and discussed. The results demonstrated that the core–shell is characterized by a dual-core structure, comprising a Co, Ti-rich nucleus, a core with particle morphology enriched in Co, Fe, and Ti elements located in the center of the nucleus, and a shell with cactus-like morphology enriched in Fe and Co elements. The formation of the cactus-like core–shell structure in the FeCoNiTiAlV alloy is contingent upon the Ti/Al ratio exceeding 8:4. This process is divided into three distinct stages: (1) nonequilibrium crystallization and elements segregation; (2) component subcooling and the formation of the shell; (3) Fe segregation and precipitation with particles in the core. This study offers insight into the heterogeneous structure of multiprincipal element alloys and presents a promising strategy for their design with high properties.