稀土La对铁基耐蚀合金抗氧化性能的影响

通过X射线衍射(XRD)、扫描电镜(SEM)及能谱分析(EDS)等手段对不同La含量的铁基耐蚀合金850 ℃下的抗氧化性能进行了研究。结果表明,在850 ℃条件下,随着稀土La含量的增加,在一定程度上降低了合金的抗氧化性能,但氧化膜与基体的粘附性却得到了大大提高。La含量增加后,促进了氧的内扩散,使内氧化层呈树枝状深入合金基体,对氧化膜起到钉固作用。氧化膜主要由3个区域组成:外层是Fe₂O₃与CuO混合层,并含有少量CuFe₂O₄;中间层是以NiFe₂O₄为主的保护层,并含有少量的Fe₂O₃、NiO;内层则是以Fe₂O₃为主并含有少量NiO氧化物的内氧化区。

Effect of La content on oxidation resistance of Fe-based corrosion resistant alloy

Oxidation resistance of Fe-base corrosion resistant alloys with different La content at 850 ℃ was studied by using XRD, SEM and EDS techniques. The results show that at 850 ℃, with the increase of La content, the anti-oxidation property of the alloy is reduced to a certain extent, but the adhesion of the oxide film to the matrix is greatly improved. The oxide film can be fixed on the alloy matrix tightly with the increase of La content by promoting the internal diffusion of oxygen and make the inner oxide layer become dendritic and go deep into the alloy matrix. The oxide film is mainly composed of three layers: the outer layer is the mixed layer of Fe₂O₃ and CuO, and contains a small amount of NiFe₂O₄; the middle layer is a protective layer dominated by NiFe₂O₄, and contains a small amount of Fe₂O₃ and NiO; the inner layer is an inner oxidation zone dominated by Fe₂O₃ and contains a small amount of NiO oxide.