Shape Memory Behavior of Highly Ni-Rich NiTi Alloys

NiTi alloy is the most widely used SMA for electrical, mechanical and bio-medical applications due to its good ductility and excellent shape memory behavior. High Ni-rich NiTi SMAs are coming into prominence owing to their high strength, damping and surface finish qualities. In this study, effects of heat treatments (from 400 to 600°C) on the shape memory properties and compressive mechanical behavior were investigated on highly Ni-rich Ni-Ti alloys. It was revealed heat treatments and applied stress could significantly alter the transformation temperatures and shape memory effect response. High Ni-rich NiTi alloys has the ability exhibit perfect shape memory effect under high stress levels of 1 GPa and perfect superelasticity when up to 2 GPa was applied  after selected heat treatments in compression.