Cr含量对CrxMoNbTiZr系高熵合金组织与性能的影响

采用真空电弧熔炼的方法制备了Cr_xMoNbTiZr系高熵合金(x=0, 0.5, 1, 1.5)。利用X射线衍射仪(XRD)、扫描电镜(SEM)、能谱仪(EDS)、显微硬度计以及电化学工作站研究了Cr含量对该高熵合金结构、组织、硬度和耐蚀性能的影响。结果表明，Cr的添加使合金由单相BCC结构转变为富Zr相与富Mo-Nb相的双相BCC结构，随着Cr含量增加，在富Zr相中还有富Cr的Laves相析出；Cr_1.5MoNbTiZr合金具有最高硬度765.53 HV,这是由于第二相析出强化、固溶强化与高熵合金晶格畸变的共同作用；Cr的加入增加了Cr_xMoNbTiZr系高熵合金在质量分数为3.5%NaCl溶液中发生腐蚀倾向，但降低了该系高熵合金的腐蚀速率，同时发现Cr的添加存在一个临界值来保证合金的抗点蚀能力，超过这个临界值合金就会更容易发生点蚀现象。

Effect of Cr content on microstructure and properties of CrxMoNbTiZr high-entropy alloys

Cr_xMoNbTiZr high-entropy alloys (x=0, 0.5, 1, 1.5) were prepared by vacuum arc melting. X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), microhardness tester and electrochemical workstation were used to study the effect of Cr content on the crystallographic structure, microstructure, hardness and corrosion resistance of the high-entropy alloy. The results show that the addition of Cr makes the alloy change from a single-phase BCC structure to a dual-phase BCC structure of Zr-rich phase and Mo-Nb-rich phase. With the increase of Cr content, there is also a Cr-rich Laves phase precipitate in the Zr-rich phase. The Cr_1.5MoNbTiZr alloy has the highest hardness of 765.53 HV, which is due to the combined effect of the second phase precipitation strengthening, solution strengthening and high-entropy alloy lattice distortion. The addition of Cr increases the corrosion tendency of the Cr_xMoNbTiZr high entropy alloy in 3.5%NaCl solution (mass fraction), but reduces the corrosion rate of this high entropy alloy. Meanwhile, it is found that the addition of Cr has a critical value to ensure the pitting resistance of the alloy, beyond which the alloy is more prone to pitting.