电弧熔炼Cr-40Ti-20Nb三元合金的组织与压缩性能

摘要

采用真空非自耗电弧熔炼的方法制备了Cr-40Ti-20Nb(原子分数)合金.利用光学显微镜(OM),X射线衍射(XRD),扫描电镜(SEM)分析了合金不同凝固位置处的相组成和组织形态.结果表明,合金的凝固组织主要是由Laves相Cr2(Nb,Ti)枝晶组织及丁i的固溶体组成.同时对合金的显微硬度和压缩性能进行了测试,显微硬度值在6 112～7 350MPa之间,比Laves相Cr2Nb的显微硬度低20％.另外室温压缩屈服强度可达1 334-1 524 MPa,与采用多种合金化元素的Cr-12Nb-4Re-2Al合金相当,这表明Ti元素的添加不仅可以改变Laves相Cr2Nhb合金的凝固组织,而且对其塑性也有很大程度的改善.%The ternary alloy Cr-40Ti-20Nb was successfully prepared by vacuum non-consumable arc melting. The alloy solidified microstructure and compression behavior were investigated by using optical microscope (OM), X-ray diffraction (XRD) as well as scanning electron microscope (SEM). The results show that the solidified microstructure of the ternary alloy Cr-40Ti-20Nb was mainly composed of Laves phase Cr2(Nb2 Ti) and Ti solid solution. As the solidification position was varied from the top to the bottom of the arc-melting ingot, the microhardness of the ternary alloy was measured ranging from 6 112 to 7 350 MPa, less than that of the Laves phase Cr2Nb by a factor of 20%. Moreover, the compression yield strengths of the ternary changed from 1 334 to 1 524 MPa at room temperature, close to that of the multi-component alloy Cr-12Nb-4Re-2Al. According lo these experimental results, Tl additions not only change the solidified microstructures of the Laves-phase Cr2Nb alloy, but also remarkably improve the plasticity of the Laves phase Cr2Nb alloy.