Elastic investigation for the existence of B33 phase in TiNi shape memory alloys using atomistically informed Eshelby’s ellipsoidal inclusion

Abstract

The existence of the B33 phase in TiNi alloys, which was reported to be a stable phase using density functional theory calculations but not confirmed experimentally, is controversial. Using Eshelby’s ellipsoidal inclusion, which was atomistically informed by density functional theory calculations, we investigated the existence of the B33 phase in the TiNi shape memory alloy. The calculated total strains of the heterogeneously nucleated B33 phase were similar to the eigenstrains of the B19’ phase, which were also calculated using density functional theory calculations. Considering the similarity of the atomic structures of B33 and B19’, this indicates that the B33 phase was elastically suppressed and changed to the B19’ phase by the original B2 matrix. We confirmed that the elastic inhomogeneity between the B2 matrix and B33 phase plays a role in this change.