Young's modulus evolution and texture-based elastic-inelastic strain partitioning during large uniaxial deformations of monoclinic nickel-titanium

The authors draw upon recent first-principles calculations of monoclinic NiTi elastic constants to develop a combined numerical-empirical, texture-based approach for calculating the Young's modulus of polycrystalline, monoclinic nickel-titanium specimens. These calculations are carried out for load direction inverse pole figures measured in situ via neutron diffraction during tension-compression deformations to ∼18% true strain, as well as unloading events. As demonstrated by application to this empirical data set, the texture-based approach results in the ability to quantify the evolution of Young's modulus and to micromechanically partition elastic and inelastic macroscopic strains for the entirety of non-linear and asymmetric uniaxial deformations, a result that had not been achieved previously for a monoclinic material.