Investigating the effect of elastic anisotropy on martensitic phase transformations at the nanoscale

In this paper, the phase field approach and the finite element method are used to study the effect of elastic anisotropy on martensitic phase transformations (PTs). This anisotropy is included through the Murnaghan two-constant elastic potential which constants are functions of austenite and different martensitic variants. Martensitic PTs are considered for NiAl. The interface propagation is studied under different thermal and mechanical loadings. It is revealed that the effect of elastic anisotropy is more pronounced considering thermal strain. Thus, the interplay of elastic, transformational and thermal strains is investigated. The thermal induced growth of a martensitic nucleus is investigated for both isotropic and anisotropic cases with thermal strain and without it. The formation of a M-M interface is also studied and the effect of elastic anisotropy on the interface width and stress field is investigated. Martensitic PTs for two variants are studied under different loadings. Martensitic PTs for two variants are studied in the presence of a hole for both isotropic and anisotropic cases. This pronounces the significant effect of heterogeneous stress concentration and the size on the PTs. Surface-induced PT for two martensitic variants is also studied for both isotropic and anisotropic cases through applying a variable surface energy on the surface. Moreover, martensitic PTs for two variants are studied under different applied strains for both isotropic and anisotropic cases and the heterogeneity of the transformation work was discussed. The obtained results reveal a significant effect of elastic anisotropy on martensitic PTs.