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研究了新型定向凝固镍基高温合金DZ68的抗热腐蚀性能, 并与K438合金进行了比较. 结果表明: 热处理态DZ68合金组织中几乎没有(γ+γ') 共晶, 碳化物尺寸小,其整体组织比较均匀; 在热腐蚀过程中发生比较均匀的腐蚀, 其外腐蚀层的腐蚀产物主要是(Ni, Co)Cr₂O₄, 内腐蚀层的腐蚀产物主要是Al₂O₃. 热处理态K438合金组织中存在较多的 (γ+γ'共晶和数量较多、尺寸较大的长条状碳化物, 组织均 匀性较差; 在热腐蚀过程中发生不均匀腐蚀, 其外腐蚀层的腐蚀产物主要是NiO, 内腐蚀层的腐蚀产物主要是CrS.两种合金中Ti元素的偏析有促进其它元素偏析的倾向, 使合金组织的均匀性恶化,热腐蚀均匀性变差. 在本实验条件下, DZ68合金的抗热腐蚀性能略好于K438合金.

The hot corrosion resistance of a new directional solidification (DS) Ni–based super-alloy DZ68 was studied and compared with K438 alloy. The results indicate that the microstructure of DZ68 alloy is more uniform than K438 alloy after heat treatment. There are small size carbides in the microstructure of DZ68 alloy after heat treatment, but there are big size carbides and a lot (γ+γ') eutectic in the microstructure of K438 alloy. The hot corrosion of DZ68 alloy is uniform, and the corrosion products are mainly (Ni, Co)Cr₂O₄ and Al₂O₃. More (Ni, Co)Cr₂O₄ exists in outer corrosion layer and more Al₂O₃ exists in inner corrosion layer. For the K438 alloy the hot corrosion is not uniform, NiO is the mainly corrosion product in outer corrosion layer and CrS is the main corrosion product in inner corrosion layer. Moreover, the segregation of Ti can induce segregation of other elements in the two alloys, which leads to a severe local corrosion of alloys. Under the same expermental condition, the corrosion resistance of DZ68 alloy is a little better than that of K38 alloy.