A study on NiTiNbCo shape memory alloy

The influence of Co on the microstructure, phase transformation temperature, mechanical properties and shape memory effect of TiNiNb alloys has been investigated by X-ray diffraction, differential scanning calorimetry, tensile stress–strain measurements and bending tests, respectively. The results show that the addition of Co suppresses the brittle (Ti,Nb)2Ni phase of NiTiNb alloys, and the phase transformation temperature and lattice parameter of Ni46.5−xTi44.5Nb9Cox alloys are decreased with the increase of Co content. The yield strength of NiTiNb alloys has been improved due to the addition of Co. In particular, Ni45.5Ti44.5Nb9Co1 alloy exhibits highest yield strength among the Ni46.5−xTi44.5Nb9Cox (Co = 0.5, 1, 1.5, 2) alloys, and a maximum completely recoverable strain of 7.8% has been achieved.