Intergranular strains in transforming NiTi alloys

Shape memory alloys (SMAs) exhibit unique thermomechanical properties due to a reversible martensitic phase transformation. Their current high cost and the insufficient predictability of the thermomechanical responses of these materials hinders further growth in their application. Neutron diffraction offers a unique tool to probe the phase transformation of bulk materials in situ during thermal and mechanical loading, allowing the simultaneous monitoring of phase fraction, texture evolution, interphase and intergranular strains. This paper describes the initial results of thermomechanical loading tests of the shape memory material NiTi as it martensitically transforms in complex thermomechanical load cycles. When fully analyzed this experimental data will provide crucial information on the interaction between the transformed and untransformed material, and on the dependence of transformation on grain level orientation.