铁基合金上几种常见氧化层开裂及剥落的声发射研究

A Study on the Cracking and Spalling of Some Common Oxide Scales Formed on Iron-Base Alloys by AE

用声发射（ＡＥ）技术研究了铁基合金上几种常见氧化层在恒温氧化和随后冷却过程中发生的开裂及剥落行为。获得了ＡＥ累积计数及温度对时间的变化曲线。通过显微镜、扫描电镜的观察和Ｘ射线射衍物相分析，确定了实验合金表面氧化层的主要物相。结果表明：除了加Ｓｉ合金的氧化层在恒温氧化过程已开裂外，其余合金的氧化层均在冷却时开裂并剥落。Ｆｅ２５Ｃｒ－１０Ａｌ合金上α－Ａｌ２Ｏ３层的开裂及剥落最为剧烈。Ｆｅ－２５Ｃｒ－７．５Ｎｂ合金的Ｃｒ２Ｏ３层ＡＥ总计数远远高于Ｆｅ－２５Ｃｒ合金。而Ｆｅ－２５Ｃｒ－４Ｔｉ和Ｆｅ－２５Ｃｒ－９Ｍｎ的情况与Ｆｅ－２５Ｃｒ大体相同。

The cracking and break up of some common oxide scales on the iron-base alloys during their oxidation at a constant temperature and in the subsequent cooling process has been studied by means of an acoustic emission(AE) technique.The time dependence of the accumulation counts and the temperature were obtained.The phase species of oxide scales on the tested alloys were determined by a microscope,a scanning microscope and especially the X-ray diffraction analysis.It can be stated from the experimental results that the oxide scales on alloys cracked and broke up during the cooling process except for the oxide scale on the alloy containing silicon which cracked in the period of the constant temperature oxidation.The α-Al2O3 scale on Fe-25Cr-10Al cracked and exfoliated most severly.The total counts of AE of the Cr2O3 scale on the Fe-25Cr-7.5Nb alloy is much higher than that of Fe-25Cr.The situations of Fe-25-Cr-4Ti and Fe-25Cr-9Mn alloys were similar to that of Fe-25Cr.