A novel TiNiNb shape memory alloy with high yield strength and high damping capacity

摘要

TiNi shape memory alloys exhibit excellent damping capacity in martensite state or during the martensitic transformation. However, the alloys in these situations are very soft (as low as 100 MPa) due to the reorientation of martensite variants or detwinning in the deformation process. In the present paper, we report NiTiNb shape memory alloys with high yield strength (287 MPa) and high damping capacity (Q~(-1) greater than 10~(-2)). The NiTiNb alloys are characterized by a composite feature in microstructure, i.e. isolated martensitic NiTi(Nb) islands were randomly distributed in the eutectics of B2-TiNi(Nb) and P-Nb. The isolated NiTi(Nb) phase provides excellent damping capacity and the eutectics contribute to high yield strength. The influence of Nb addition on the microstructure, phase transformation temperature, damping capacity and the mechanical properties of the TiNiNb alloys were reported.