(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 通过真空铸造得到Ni-10%Fe-10%Al-10%Cu(质量分数)及分别添加0.8%Y、5.3%Ta和13.6%Cr(质量分数)的Ni-Fe-Al-Cu-X(X：Y或Ta或Cr)4种合金，采用熔盐腐蚀实验及SEM，XRD及EDX测试研究各合金在850 ℃静态冰晶石熔盐气氛中的腐蚀行为。结果表明：在850 ℃冰晶石熔盐气氛中，Ni-10%Fe-10%Al-10%Cu合金表面形成的氧化物保护膜；由于氧的聚集、扩散，并在熔盐/氧化膜界面处发生O2+2e=2O2−还原反应，而生成的O2−与MeO反应生成MeO22−，致使NiO和Al2O3等氧化物层疏松、多孔、易剥落；另外，氧化物保护膜也被熔盐挥发的氟化物通过物理化学作用而溶解，形成坑洞，腐蚀层呈现层叠状；添加0.8%Y和5.3%Ta可净化合金晶界，使腐蚀层中氧化产物更致密，提高合金抗冰晶石熔盐气氛腐蚀性能；添加13.6%Cr的Ni-10%Fe-10%Al-10%Cu合金，其腐蚀层形成Cr2O3及NiCr2O4冰晶石结构的化合物，降低其他氧化物的活度，提高氧化膜的保护作用，该合金抗冰晶石熔盐气氛腐蚀性能最好。
关键字: Ni-Fe-Al-Cu合金；冰晶石熔盐气氛；Y；Ta；Cr
中图分类号：TG 146.15 文献标志码：A
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The static thermal corrosion behaviors at 850℃ in cryolite melten atmosphere by adding 0.8%Y, 5.3%Ta and 13.6%Cr (mass fraction), respectively, in Ni-10%Fe-10%Al-10%Cu cast alloys were investigated by SEM, XRD and EDX. The results indicate that, the oxides layer is formed on the surface of Ni-10%Fe-10%Al-10%Cu (mass fraction) alloy. The reductive reaction O2+2e=2O2− takes place on the interface between melt salt and oxides layers due to the concentration and diffusion of oxygen. The oxides layers as NiO and Al2O3 tend to be loose, porous and easy to be peeled off because of MeO22− produced by the reaction between O2− and MeO. In addition, the oxide layers on the surface of Ni-10%Fe-10%Al-10%Cu alloy can easily be dissolved by fluoride volatized from molten salt after physical and chemical reactions, then the corrosion products are laminated. Adding 0.8%Y and 5.3%Ta can clear the impurities at grain boundaries and densify the oxides in the corrosion layer, thus the high temperature corrosion resistance of alloys in cryolite melten atmosphere is improved. The Ni-10%Fe-10%Al-10%Cu alloy with adding 13.6%Cr has the best corrosion resistance in cryolite melten atmosphere because the main oxides in corrosion layer are Cr2O3 and NiCr2O4, which can inhibit the activities of the other oxides and enhance the protective ability of the oxide layers.
Key words: Ni-Fe-Al-Cu alloy; cryolite melten atmosphere; Y; Ta; Cr
