In Situ Neutron Diffraction Study of NiTi–21Pt High-Temperature Shape Memory Alloys

In situ neutron diffraction was used to investigate the microstructural features of stoichiometric and Ti-rich NiTiPt high-temperature shape memory alloys with target compositions of Ni 29 Ti 50 Pt 21 and Ni 28.5 Ti 50.5 Pt 21 (in atomic percent), respectively. The alloys’ isothermal and thermomechanical properties (i.e., moduli, thermal expansion, transformation strains, and dimensional stability) were correlated to the lattice strains, volume-averaged elastic moduli, and textures as determined by neutron diffraction. In addition, the unique aspects of this technique when applied to martensitic transformations in shape memory alloys are highlighted throughout the paper.