富镍镨掺杂镍钛形状记忆合金的微结构、相变特性与硬度

Effect of Pr Addition on Microstructure,Phase Transformation Behavior,and Hardness of Ni-Rich NiTi Shape Memory Alloy

采用真空熔炼法向NiTi二元合金中掺杂Pr稀土元素,制备了多组分原子分数的Ni_(50)Ti_(50)-xPrx(x=0,0.1,0.3,_(0.5),0.7,0.9)合金。研究了Pr元素的添加对NiTi合金金相组织、相变温度和硬度的影响。结果表明,Ni_(50)Ti_(50)-xPrx合金由NiTi基体与NiPr夹杂相组成,其中Ni_(50)Ti_(49.5)Pr_(0.5)合金的马氏体相变温度达73℃,合金的热滞窄至37℃,维氏硬度约为28_(50)MPa。Pr元素的添加显著降低了NiTi合金的马氏体相变温度,同时,与其他NiTi基合金相比,NiTiPr合金保持了较窄的热滞和较高的硬度。

The influence of Pr addition on the microstructure,phase transformation,and hardness of Ni_(50)Ti_(50)-xPrx(x=0,0.1,0.3,0.5,0.7,0.9,at%)shape memory alloys was investigated.Results show that Ni_(50)Ti_(50)-xPrx alloys consist of NiTi matrix and NiPr precipitates.Ni_(50)Ti_(49.5)Pr_(0.5)alloy has the optimal properties of martensitic transformation start temperature of 73℃,the thermal hysteresis as narrow as 37℃,and the Vickers hardness of 28_(50)MPa.Pr addition obviously decreases the martensitic transformation temperature of NiTi alloys,but the composite alloy maintains a relatively narrow thermal hysteresis and relatively high Vickers hardness,compared with other NiTi-based shape memory alloys.