Effects of Nb on the Microstructure and Compressive Properties of an As-Cast Ni(44)Ti(44)Nb(12) Eutectic Alloy

The addition of Nb can form a eutectic phase with a NiTi matrix in a NiTi-based shape memory alloy, improving the transition hysteresis of the NiTi alloy. A Ni(44)Ti(44)Nb(12) ingot was prepared using the vacuum induction melting technique. Under compression deformation, the yield strength of the NiTi–Nb alloy is about 1000 MPa, the maximum compressive strength and strain can reach 3155 MPa and 43%, respectively. Ni(44)Ti(44)Nb(12) exhibited a superelastic recovery similar to that of the as-cast NiTi(50). Meanwhile, the loading–unloading cycle compression shows that the superelastic recovery strain reached a maximum value (2.32%) when the total strain was about 15%, and the superelasticity tends to rise first and then decrease as the strain increases.