The microstructure and shape memory effect of Ti–16 at.%Nb alloy

The microstructure, phase composition, mechanical properties and shape memory effect of the Ti–16 at.%Nb alloy were investigated by means of TEM, XRD, bending test and tensile test. The XRD results showed that the Ti–16 at.%Nb alloy is mainly composed of two phases: α″ phase and β phase at room temperature. TEM observation proved that there is also a little amount of ω phase in the Ti–16 at.%Nb alloy solid solution treated at 750 °C for 0.5 h. The martensite lath with a sub-structure of (111) type I twin was found in the Ti–16 at.%Nb alloy solid solution treated at 750 °C for 0.5 h by TEM observation. While solid solution treated at 750 °C, the Ti–16 at.%Nb alloy has the best combination of mechanical properties. The Ti–16 at.%Nb alloy has a certain shape memory effect. When the pre-strain is less than 2%, the deformed alloy can completely recover to the original shape. The SME of the Ti–16 at.%Nb alloy has an acceptable reproducibility, because when pre-deformed with 3.26% strain, after more than 20 times deformation cycling, the recovery ratio is still more than 40%.