Structure, phase transformation, and hardness of NiTiHfNd alloys

Abstract

Abstract Ni50Ti29Hf21−x Nd x (x = 0, 1, 2 at.%) and Ni50Ti29−x Hf21Nd x (x = 1, 2 at.%) alloys were fabricated via arc melting. For the first time, the influence of Nd addition on structure, phase transformation, and hardness of NiTiHf alloy was investigated experimentally. It is found that the NiTiHfNd alloys consist of NiTiHf matrix and Nd-rich precipitates. Ni50Ti29Hf21 alloy demonstrates a martensitic transformation temperature as high as 314.1 °C, a thermal hysteresis as narrow as 37.7 °C, and a Vickers hardness as high as 500 HV. Nd addition obviously decreases the martensitic transformation temperature of NiTiHf alloys but still maintains a relatively narrow thermal hysteresis and a relatively high Vickers hardness compared with most other components of NiTiHf-based alloys.

Keywords

• NiTiHfNd
• Microstructure
• Phase transformation
• Hardness