Single-phase high-entropy intermetallic compounds(HEICs): bridging high-entropy alloys and ceramics

High-entropy intermetallic compounds(HEICs)were fabricated by mechanical alloying and spark plasma sintering to fill a knowledge gap between the traditional high-entropy alloys(HEAs)and emerging highentropy ceramics(HECs).Notably,several four-or five-component equimolar aluminides,such as the B2-phase(Fe1/5Co1/5Ni1/5Mn1/5Cu1/5)Al,have been made into single-phase HEICs for the first time.Thermodynamic modeling and a reversible,temperature-dependent,phase-stability experiment suggest that such B2-phase HEICs are entropy-stabilized phases.The structure of these HEICs resembles that of HECs with high-entropy mixing of fo ur or five elements of nearly equal fractions in one and only one sublattice,but with significant(~10%)anti-site defects(differing from typical HECs).A new phase stability rule for forming single B2-phase HEICs is proposed.Five additional HEICs of predominantly D022phases have also been made.This study broadens the families of equimola r,single-phase,high-entropy materials that have been successfully fabricated.