Abstract
Refractory intermetallic compounds are potential candidates for high-temperature applications owing to their high thermal stability and excellent softening resistance. However, they suffer from the pest oxidation phenomenon at low temperatures, which highly restricts their applications. Here, after determining the stable segregated phases in complex mixtures of refractory elements, two novel refractory intermetallic compounds with complex compositions are engineered, (Ti 1/5 Zr 1/5 Nb 1/5 Hf 1/5 Ta 1/5 )Al 3 and (Mo 1/3 W 1/3 Ta 1/3 )Si 2 . These two single-phase materials exhibit excellent oxidation resistance with complete suppression of pest phenomenon in the as-cast state. Exploring the underlying oxidation resistance mechanisms, it is found that the synergistic effect of high entropy lattice sites and the ability of Si and Al elements to develop a dense protecting layer are the main reasons for the complete elimination of the pest oxidation. Besides, we introduce and verify a sublattice electronegativity difference criterion as a new indicator for forming single-phase high and medium entropy materials. The approach to engineering single-phase entropy-stabilized intermetallic compounds reported here can be used to develop additional medium- and high-entropy intermetallic compounds with tailorable properties. The raw/processed data required to reproduce these findings are available from the corresponding author upon reasonable request. • A novel approach to design chemically complex intermetallic compounds (CCICs) is developed. • (Ti 1/5 Zr 1/5 Nb 1/5 Hf 1/5 Ta 1/5 )Al 3 RHEIC exhibits a single tetragonal D0 22 structure. • (Mo 1/3 W 1/3 Ta 1/3 )Si 2 RMEIC possesses a nearly single hexagonal C40 structure. • The pest oxidation could be completely eliminated in both CCICs. • A modified sublattices electronegativity difference parameter is introduced.
Published Version
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