Mechanical behavior in NiTiNb shape memory alloys with low Nb content

Effect of low Nb content (3.5 at.%, 4.5 at.%, 5.0 at.%) on the mechanical properties of NiTiNb shape memory alloy (SMA) has been investigated in detail by differential scanning calorimetry (DSC), tensile test and scanning electron microscope (SEM). The Ms temperatures of three kinds of NiTiNb alloys with different Nb content were fixed at about 188 K to eliminate the influence of testing temperature on the mechanical behaviors. The experimental results show that with the increase of Nb content, the yield strength increased and the elongation decreased gradually. However, the NiTiNb alloys still keep high elongation property. Furthermore, it has been found that the shape recovery strain of NiTiNb alloy with 5.0 at.% Nb can reach 7.4%. It is believed that NiTiNb alloys with low Nb content can obtain good shape memory characteristic.