硼含量对Fe-Cr-Al合金高温氧化层结构的影响

Effect of trace boron on oxide layer structure of Fe-Cr-Al alloy at high temperature

以添加不同硼含量的Fe-Cr-Al合金为试验材料,在1220℃下热处理之后,采用X射线衍射、扫描电镜、能谱分析等方法,研究硼含量对Fe-Cr-Al合金在1220℃下氧化层结构的影响。结果表明,当不含硼时,合金氧化层由外层Fe_2O_3,内层为(Fe_(0.6)Cr_(0.4))_2O_3、(Al_(0.9)Cr_(0.1))_2O_3两层氧化层构成;硼含量为8×10^(-6)时,合金氧化层由外层Fe_2O_3、(Fe_(0.6)Cr_(0.4))_2O_3,内层(Al_(0.9)Cr_(0.1))_2O_3两层氧化层构成;硼含量为18×10^(-6)时,合金氧化层由多层氧化层转变为单层Al2O3层,且局部区域发生氧化失稳,生成瘤状氧化层,存在贯穿性微裂纹。因此为了保证1220℃下合金不生成瘤状氧化层,硼的添加量不应超过8×10^(-6)。

Taking Fe-Cr-Al alloy with different boron content as test material,the oxide layers were studied by X-ray diffraction analysis,microscopic morphology observation and energy spectrum analysis,as a objective to evaluate the effect of boron on the oxide layer structure of Fe-Cr-Al alloys at temperature 1220 ℃. The results show that when not containing boron,the outer layer is Fe2O3,while the inner layer is composed of（ Fe0. 6Cr0. 4）2O3and（ Al0. 9Cr0. 1）2O3; When boron content of the alloy is 8 × 10^-6,the outer oxide layer is composed of Fe2O3and（ Fe0. 6Cr0. 4）2O3,while the inner oxide layer is composed of（ Fe0. 6Cr0. 4）2O3and（ Al0. 9Cr0. 1）2O3; When boron content of the alloy is18 × 10^-6,two layers of oxide transform into single alumina scale,the oxidation becomes instability in some local area of the alloy,and forms tumor oxide layer in which penetrative cracks are observed. Therefore,the content of boron in the alloy should not exceed 8 × 10^-6in order ensure tumor oxide layer does not formed.