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采用扫描电镜和X射线衍射方法研究了添加微量Dy元素(0～0.1%(质量分数))对Ni-44Ti-6Al合金微观组织的影响,并采用力学压缩实验研究了合金的室温和高温力学性能。结果表明,Dy元素在Ni-44Ti-6Al合金中的NiTi基体相中固溶,但其固溶度仅为0.03%(原子分数),同时使晶粒细化。超量的Dy以氧化物的形式析出,大部分呈颗粒状分布在晶界。适量的Dy能够有效提高合金的室温屈服强度和塑性。添加0.05%Dy的合金的屈服强度和塑性变形率均达到最大值,分别为1570 MPa和10.9%;Dy含量继续增加,合金的屈服强度和塑性变形率有所下降。Dy能够显著提高合金在600～800℃下的屈服强度,添加0.05%Dy合金的屈服强度最高。Dy对合金力学性能的改善主要归因于晶粒细化和固溶强化作用。
The microstructure of Ni-44Ti-6Al alloy with addition of trace Dy (0 ~ 0.1% (mass fraction)) was investigated by scanning electron microscopy and X-ray diffraction. The mechanical properties of the alloy at room temperature and elevated temperature . The results show that the Dy element forms a solid solution in the NiTi matrix phase in Ni-44Ti-6Al alloy, but its solid solubility is only 0.03% (atomic fraction), meanwhile the grain size is refined. Excessive amount of Dy precipitates in the form of oxides, most of which are distributed in grain boundaries at grain boundaries. The proper amount of Dy can effectively improve the room temperature yield strength and ductility of the alloy. The yield strength and plastic deformation rate of alloys with addition of 0.05% Dy reached the maximum value of 1570 MPa and 10.9%, respectively. The content of Dy continued to increase, and the yield strength and plastic deformation rate decreased. Dy can significantly improve the alloy yield strength at 600 ~ 800 ℃, adding 0.05% Dy alloy highest yield strength. The improvement of the mechanical properties of Dy alloy is mainly due to grain refinement and solution strengthening.