Computational analysis of phase-transformation-induced deformation in coated polycrystalline titanium nickelide

Numerical simulation of deformation in the surface layer of coated polycrystalline titanium nickelide is performed. The coating is synthesized from a layered Ti/Ni/Ti nanolaminate. The polycrystalline microstructure is studied by electron backscatter diffraction (EBSD) analysis. Based on the available experimental data, a model microstructure of the polycrystalline composite assuming the grain orientation is created. An anisotropic constitutive model of composite elastoplastic deformation is developed taking into account the cubic syngony, slip systems, and phase transition. The microstructure and model are integrated into ABAQUS/Explicit. Finite element calculations of tension and subsequent unloading of the microstructure are performed. The interrelated processes of nucleation and propagation of elastic phase transformation in titanium nickelide and elastoplastic flow in the coating layer are studied. It is found that the phase transition in the base material contributes to a more uniform distribution of strains, while the plastic flow in the coating leads to the formation of residual martensite in the titanium nickelide surface layer.