Microstructure and shape memory effect of Ti–20Zr–10Nb alloy

Abstract

The microstructure, martensitic transformation behavior and shape memory effect of Ti–20Zr–10Nb shape memory alloy have been studied by X-ray diffraction (XRD), optical microscopy (OM) and transmission electron microscopy (TEM) observation, differential scanning calorimetry (DSC) and tensile stress–strain measurements. The results show that the recrystallization occurs in the cold rolled Ti–20Zr–10Nb alloy by annealing at 600 °C and the grain size goes up with the increasing annealing temperature up to 800 °C. The Ti–20Zr–10Nb alloy is primarily composed of α″ martensite and a small amount of ω phase which appears after annealing. A reverse martensite transformation temperature higher than 500 °C upon heating has been detected for the Ti–20Zr–10Nb alloy annealed at 600 °C, but no obvious exothermic behavior can be found upon cooling. The tensile strength and the failure strain of the alloy are measured to be 542 MPa and 13.1%, respectively, associated with a maximum shape recovery strain of about 2.5%.