Synthesis and characterization of novel high entropy Heusler intermetallics.

This study aims at developing novel Full-Heusler high entropy intermetallic compounds (FH-HEICs). To this end, the formation of Heusler-type intermetallic structures and their thermal stability are studied in three systems with (CoFeNiCuV) 2 MnAl, Co 2 (FeMnNiCuTi)Al and Co 3 (FeMnNiCu)Al chemical compositions, where one sublattice composed of multi-component elements. The results indicated that (CoFeNiCuV) 2 MnAl crystallizes in a pure FH-HEIC type phase consisting of ordered L2 1 and disordered A2 structures, and it remains stable after 5 h annealing at 900 °C. Annealing could effectively suppress segregation of elements in (CoFeNiCuV) 2 MnAl, but it did not trigger substantial disorder-to-order phase transition. Co 2 (FeMnNiCuTi)Al crystallized in a mixture of B2 and FCC phases, in which the ordered B2 structure undergoes a transition to disordered A2 type structure upon annealing at 900 °C. On the other hand, Co 3 (FeNiMnCu)Al exhibited a A2+FCC two-phase structure in both as-cast and annealed states. (CoFeNiCuV) 2 MnAl exhibited higher microhardness value (589 HV) compared to Co 2 (FeMnNiCuTi)Al (474 HV) and Co 3 (FeMnNiCu)Al (417 HV) FH-HEICs, consisting with its higher degree of ordering. Finally, all the samples exhibited ferromagnetic behavior with relatively high magnetic saturation and coercivity in the range of semi hard magnetic materials. [Display omitted] • Full-Heusler high entropy intermetallic compounds (FH-HEICs) are developed. • (CoFeNiCuV) 2 MnAl FH-HEICs composed of ordered L2 1 and disordered A2 structures. • The microhardness of FH-HEICs are correlated with the degree of ordering in lattice structure. • FH-HEICs exhibited ferromagnetic behavior with relatively high magnetic saturation. • Entropy engineering is an effective route to improve functional properties of Heusler phases. [ABSTRACT FROM AUTHOR]