Influence of thermomechanical processing on the superelastic properties of a Ni-rich Nitinol shape memory alloy

Ni-rich NiTi shape memory alloys usually undergo a series of thermomechanical treatment in their production and component fabrication processes. Comprehension of property changes and microstructural evolutions induced by these treatments is essential for quality control and improvement of these materials. The effect of controlled ageing for prolonged times (of the order of several hours) has been extensively investigated in the literature. This study investigates the effect of actual production processes of NiTi tubing, which often involve thermomechanical treatment for multiple periods of short durations and which are typical of industrial production routines of devices like stents, on the transformation and deformation behaviour of a Ti-50.8 at%Ni alloy. Evolution of the properties is characterized by DSC measurements and by tensile testing at 310 K. (c) 2006 Elsevier B.V. All rights reserved.