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采用热模拟实验研究了Ni50Ti46-xAl4Hfx(x=0～6,at%)合金的微观组织特点和高温变形行为。合金由基体相NiTi和第二相Ti2Ni组成。Hf全部溶解在基体相和第二相中,并且促进了第二相的析出,显著提高了合金的高温强度。Ni-Ti-Al-Hf合金在700～800℃下变形行为的研究表明:合金具有良好的高温压缩性能,流变应力随着应变速率的减小或变形温度的增加而降低,其高温变形行为符合温度补偿幂规律描述。Hf的添加使合金的应力指数(n)和变形激活能(Q)上升,这主要是由于Hf的固溶强化、促进Ti2Ni相析出强化和高温稳定性造成的。
The microstructure and high temperature deformation behavior of Ni50Ti46-xAl4Hfx (x = 0 ~ 6, at%) alloy were studied by means of thermal simulation. The alloy consists of the matrix phase NiTi and the second phase Ti2Ni. Hf all dissolves in the matrix phase and the second phase, and promotes the precipitation of the second phase, significantly improving the high-temperature strength of the alloy. Deformation behavior of Ni-Ti-Al-Hf alloy at 700-800 ℃ shows that the alloy has good high-temperature compressive properties. The flow stress decreases with the decrease of strain rate or deformation temperature, and the deformation at high temperature Comply with temperature compensation power law description. The addition of Hf raises the stress index (n) and the deformation activation energy (Q) of the alloy, which is mainly attributed to the solid solution strengthening of Hf and the precipitation strengthening and high temperature stability of Ti2Ni phase.