稀土改性Fe-Al层表面Al2O3 薄膜的物相分布

Phase Distribution of Al2O3 Thin Films on Rare Earth-Modified Fe-Al Layer Surface

摘要:

在760 ℃下采用稀土改性包埋渗铝以及原位氧化方法制备Fe-Al/Al₂O₃复合涂层，研究了渗铝层和氧化膜的微观组织和相分布。结果表明，稀土改性渗铝层可分为3层：外层渗铝层、过渡层和内扩散层。渗铝层主要由FeAl相和Fe₃Al相组成。FeAl相主要集中在渗铝层的外层，为Al₂O₃氧化膜的选择性氧化提供了有利条件。氧化膜表面呈α-Al₂O₃脊状结构。此外，表面氧化铈的存在是由于氧化初期Ce向外扩散且与O₂的优先反应。氧化膜可分为2层，即纯α-Al₂O₃层和主要由α-Fe(Al)和Al、Fe、Ce的混合氧化物组成的过渡层。

Abstract:

Fe-Al/Al₂O₃ composite coating was prepared through rare earth-modified aluminizing and in-situ oxidation at 760 °C. The microstructure and phase distribution of the aluminizing layer and oxide film were investigated. Results show that the rare earth-modified aluminizing layer can be divided into three layers: an outer aluminizing layer, a transition layer, and an inner diffusion layer. The aluminizing layer is predominantly composed of FeAl phase and Fe₃Al phase. Notably, the FeAl phase is primarily concentrated in the outer layer of aluminizing layer, providing favorable conditions for selective oxidation of the Al₂O₃ oxide film. The surface of oxide film exhibits the α-Al₂O₃ ridge structure. Additionally, the presence of Ce oxide on the surface is attributed to the outward diffusion of Ce and its preferential reaction with O₂ during the initial oxidation stage. The oxide film can be divided into two layers, namely a pure α-Al₂O₃ layer and a transition layer which is mainly composed of α-Fe(Al) and mixed oxides of Al, Fe, and Ce.