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

Abstract

In situ neutron diffraction was used to investigate the microstructural features of stoichiometric and Tirich 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.

The effect of vanadium and nickel on the microstructure and transformation temperatures of Ti50Pt50 alloy

“…Moreover, solid solution strengthening was also found to improve high temperature strength of Ti50Pt50 alloy [1][8][9] [10]. Previous studies reported that, partial substitution of Pt with Ni, Ti50Pt21Ni29 and Ti50.5Pt21Ni28.5 alloys, showed an improved work output and reduced transformation temperatures (Af less than 500 • C) [11] when compared to Ti50Pt50 alloy. However, partial substitution of Ni with Pt in TiNi alloys results in high temperature transformation properties and the ability to perform work under relatively high stress conditions at high temperatures [12].…”