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通过自编软件建立了Fe-Cr-Al合金表面、氧化膜/基体界面模型,采用递归法计算了合金元素在Fe-Cr-Al合金表面、氧化膜/基体界面的环境敏感镶嵌能、亲和能、结合能、态密度等电子结构参数.从电子层次系统研究了Fe-Cr-Al合金氧化膜的形成机理、稀土元素和杂质硫对氧化膜形成过程及黏附性的影响机理.研究表明Fe-Cr-Al合金中Al的偏聚驱动力远大于Y,Cr.氧化初期氧从合金表面向合金内部扩散,合金内部Al向合金表面扩散,使合金形成富铝、氧表面层;氧与Al间的亲和力较大(亲和能低),氧原子容易与Al结合生成Al2O3保护膜;合金中加入Y后,Y在合金表面偏聚,抑制Al向合金表面扩散,氧化膜的横向生长得到有效控制,从而避免氧化膜皱褶形貌的发生,提高氧化膜的黏附性;合金内部的S通过扩散汇集在基体/氧化膜界面,S使界面区原子的总能增高,总态密度降低,减小了界面的稳定性,进而削弱氧化膜与合金基体的结合力.
The interface model of Fe-Cr-Al alloy and oxide film / matrix was established by self-made software. The environment-sensitive inlay and affinity of alloying elements on the surface of Fe-Cr-Al alloy and oxide / Energy, bonding energy and density of states, etc. The formation mechanism of the oxide film of Fe-Cr-Al alloy and the influence mechanism of rare earth element and impurity sulfur on the formation process and adhesion of the oxide film were studied from the electronic hierarchy system. The driving force for the segregation of Al in -Cr-Al alloy is much larger than that of Y and Cr. In the initial stage of oxidation, the oxygen diffuses into the alloy from the surface of the alloy, and the interior of the alloy diffuses to the surface of the alloy to form the aluminum-rich and oxygen surface layer. Between the affinity of the larger (affinity and low), the oxygen atoms easily combine with Al to form Al2O3 protective film; alloy Y added, Y segregation on the alloy surface, inhibit the diffusion of Al to the alloy surface, the lateral growth of the oxide film is effective So as to avoid the occurrence of wrinkle appearance of the oxide film and improve the adhesion of the oxide film. The internal S of the alloy is collected at the interface of the substrate and the oxide film by diffusion, so that the total energy of the atoms in the interface region increases and the total state density decreases Small interface stability, Which further weakens the adhesion between the oxide film and the alloy substrate.