Neutron diffraction studies and multivariant simulations of shape memory alloys: Concurrent verification of texture development and mechanical response predictions

A new methodology has been developed to compare texture development and macroscopic response predictions of micromechanical shape memory alloy models directly with diffraction data. Using these methods empirical neutron diffraction data from sequential, multi-axial, compressive loading schemes were compared with calculations from the simplified multivariant model. Through this process the ability of a multivariant model to predict both the texture development and mechanical response trends during the creation of complex stress states in martensitic polycrystalline NiTi was demonstrated for the first time. The result made it evident that a multivariant model is more completely validated through simultaneous verification of micro and macroscale predictions as opposed to only verifying macroscale predictions, as was the previous state of the art. The new methodology presented here provides the means to perform this multiscale verification for any multivariant model. It is also shown that in combining a multivariant model with diffraction techniques a new tool for examining the plausibility of variant growth and depletion mechanisms has been created.