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采用真空非自耗电弧熔炼工艺制备了Cr2Nb-XTi(X=5,10,15,at%)合金,利用光学显微镜(OM),X射线衍射(XRD)仪,扫描电镜(SEM)对电弧熔炼态铸锭的组织进行了研究,探讨了合金化元素Ti的含量对Laves相Cr2Nb力学性能及耐蚀性的影响。结果表明:3种成分的电弧熔炼态合金凝固组织主要由C15-Cr2(Nb,Ti)相和六方的β-(Ti,Nb)以及体心立方结构的β-(Nb,Ti)相组成。在5Ti和10Ti合金冷速较小的铸锭上部凝固组织中出现了亚稳相C14-Cr2(Nb,Ti)。通过对合金力学性能研究表明,随合金化元素Ti含量的增加,Laves相Cr2Nb合金的显微硬度逐渐降低,断裂韧性增大,当Ti含量达到15at%时,合金的断裂韧性达到了3.1 MPa·m1/2,比单相Laves相Cr2Nb提高1倍。另外,对腐蚀性能的测试表明,Ti含量增加材料腐蚀性能下降,但15Ti合金仍表现出良好的耐蚀性。
The Cr2Nb-XTi (X = 5, 10, 15, at%) alloy was prepared by vacuum non-consumable arc melting process. The microstructure of Cr2Nb-XTi alloy was characterized by optical microscope (OM), X-ray diffraction (XRD) and scanning electron microscope The microstructure of the as-cast ingot was studied, and the effect of alloying element Ti content on the mechanical properties and corrosion resistance of Laves phase Cr2Nb was discussed. The results show that the solidification microstructures of the three components are mainly composed of C15-Cr2 (Nb, Ti) phase and hexagonal β (Ti, Nb) and the body-centered cubic β- (Nb, Ti) phase. The metastable phase C14-Cr2 (Nb, Ti) appeared in the solidified microstructure of the upper ingot with lower cooling rate of 5Ti and 10Ti alloys. Through the study of the mechanical properties of the alloy, the microhardness of Laves phase Cr2Nb alloy gradually decreases and the fracture toughness increases with the increase of the alloying element Ti content. The fracture toughness of the alloy reaches 3.1 MPa when the Ti content reaches 15 at% m1 / 2, which is double that of single phase Laves phase Cr2Nb. In addition, the corrosion performance of the test shows that the corrosion resistance of the material decreases with increasing Ti content, but the 15Ti alloy still exhibits good corrosion resistance.