NiAl-31Cr-3Mo合金的低温热腐蚀性能

Low Temperature Hot Corrosion Properties of NiAl-31Cr-3Mo Alloy

通过对NiAl—31Cr-3Mo合金在550℃、600℃、650℃和700℃四种温度下进行恒温热腐蚀试验，研究其低温热腐蚀行为，通过电子显微镜、SEM进行表面观察分析，探讨了NiAl—31Cr-3Mo合金的低温热腐蚀机理。结果表明：NiAl—31Cr-3Mo的热腐蚀存在孕育期，在孕育期间首先形成保护性Al2O3和Cr2O3氧化膜。在550-650℃之间，这种保护作用较为明显。最严重的低温热腐蚀发生在650-700℃之间，低温热腐蚀后合金表面为坑点状，发生点蚀，并且有贫铬、贫铝现象，这造成Mo含量升高，从而引发酸性腐蚀。

The low temperature hot corrosion behavior of NiA1-31Cr-3Mo alloy was investigated under constant temperature condition of 550℃, 600℃, 650℃ and 700℃. The microstructure of NiAl-31Cr-3Mo alloy before and after the low temperature hot corrosion were analyzed by means of optical microscopy（OM）, SEM and TEM, and the mechanism of low temperature hot corrosion was discussed. There was an incubation period at the initial stage of hot corrosion. The continuous layers of Al2O3 and Cr2O3 were formed on the surface of NiAl-31Cr-3Mo alloy which provided protective effect at 550-650℃. At 650-700℃, the hot corrosion became serious, cavities were observed in the alloy surface, indicating pitting corrosion occurred, and the basic condition for the acid corrosion of Al-poor, Cr-poor and Mo-rich phases appeared.