摘要
High-temperature stable intermetallics, such as L12-structured γ′, have been introduced as coherent precipitates in the face-centered-cubic-structured γ matrix of high-entropy compositions, creating a new class of materials called high-entropy superalloys (HESAs). HESAs have been designed to possess elevated temperature strength and oxidation resistance, and they have emerged as potential candidates to compete with conventional Ni-based superalloys with respect to cost-performance. Notably their compositions contain higher amounts of Fe and Ti, along with lower contents of refractory elements, making HESAs cheaper and lighter than those of conventional superalloys. Furthermore the unique thermodynamics and kinetics of the HESAs system have rendered interesting phase transformation pathways, resulting in hierarchical microstructures with additional strengthening contributions from high-entropy γ particle formation in the γ′ phase, and the high-entropy γ matrix also contributes to the ductility of the bulk material. This chapter summarizes the current state of the art in HESA's research and development.