Damping capacity and mechanical property of NiTiNb shape memory alloys

Two-phase NiTi base alloys (NiTi)_50-0.5xNb_x(x=5, 10, 15, 20) with both high damping capacity and high yield strength have been prepared by addition of Nb. With increasing Nb content, the fraction of eutectic (NiTi+β-Nb) increases, and yield strength in martensite state rises. When x=15, the yield strength reaches the highest value of 289 MPa. And the alloys also exhibit high damping capacity, tanδ>0.01. According to the damping mechanism for the shape memory alloys, the relationship between the damping properties and temperatures of NiTiNb alloys was explained, and phase boundary damping from the β-Nb and NiTi phases was discussed.