【摘要】 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。更多还原

【Abstract】 The effects of Dy addition on the microstructure Ni-44Ti-6Al alloy were studied through electron scanning electron microscopy(SEM) and X-ray diffraction(XRD) measurements,and the mechanical properties of Ni-Ti-Al-Dy alloys were investigated by compressive tests at room temperature and elevated temperatures.The results showed that Dy existed as a solid solution element in NiTi phase in Ni-44Ti-6Al alloy with the small solubility of 0.03%(mass fraction),and,moreover,caused the refinement of crystal grains.The extra Dy tended to form Dy-O phase,distributing as small particles in gain boundaries.The yield stress and plasticity of Ni-44Ti-6Al alloy were improved by the addition of Dy.For Ni-44Ti-6Al alloy with Dy of 0.05%,the yield stress and plasticity reached the maximum values of 1570 MPa and 10.9%,respectively,but the corresponding values decreased with further increase of Dy content.The yield strength of Ni-44Ti-6Al alloy at 600-800 ℃ was remarkably increased by the addition of Dy and it exhibited the maximum value when Dy content was 0.05%.The improvement of mechanical properties was mainly attributed to the grain refinement and solid solution strengthening effects caused by Dy.更多还原