Formation of single-phased B2 multi-principal element intermetallics: From experiments to modeling

In this study, a variety of Co-Ni-Ti-Zr alloys with various compositions were examined to identify potential single-phase B2 intermetallics. While classical theoretical models suggested that most compositions would present multiple phases or even amorphous phases, the equiatomic CoNiTiZr alloy revealed a stable single-phased B2 structure even under extended annealing at temperatures approaching its melting point. Notably, this alloy showcased desirable properties, such as a strong Elinvar effect and a high elastic strain limit. To aid in the design of B2 multi-principal elemental intermetallics (MPEIs), we proposed a pseudo-binary system model that counts for both chemical long-range order across two sublattices and random atom mixing within each sublattice. The outcome of this study is expected to accelerate the identification of valuable B2 MPEIs.