The 9Cr-1Mo steel (ASTM P91) was hot-dip aluminized, and its microstructural changes during oxidation were studied. Before oxidation, the coating consisted of (Al-rich topcoat containing a small amount of Al 5 Fe 2 and Al 13 Fe 4 )/(Al 13 Fe 4 -rich, Al 13 Fe 4 -containing alloy layer)/(Al 5 Fe 2 alloy layer containing a small amount of Al 9 Cr 4 precipitates), from the surface. During oxidation at 700–900 °C for 20–100 h, Al diffused inward and the substrate elements migrated outward to broaden and soften the coating, and also to transform (high Al)-Fe intermetallics to (low Al)-Fe intermetallics. The phases in the coating progressively transformed during oxidation as follows; (Al-rich topcoat)/(Al 5 Fe 2 –rich, Al 13 Fe 4 -containing alloy layer)/(Al 5 Fe 2 alloy layer)→(α-Al 2 O 3 scale)/(Al 13 Fe 4 –rich, Al 5 Fe 2 -containing layer)/(Al 5 Fe 2 layer)/(AlFe interlayer)→(α-Al 2 O 3 scale)/(AlFe–rich, Al 5 Fe 2 -containing layer)/(AlFe layer)/(AlFe 3 layer))→((α-Al 2 O 3 , Fe 2 O 3 )-mixed scale)/(AlFe 3 layer)/(Fe(Al) layer) from the surface. As the oxidation progressed, the scale changed from α-Al 2 O 3 to the (α-Al 2 O 3 , Fe 2 O 3 )-mixture, which provided the necessary oxidation resistance.
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机译：将9Cr-1Mo钢（ASTM P91）热浸镀铝，并研究其在氧化过程中的显微组织变化。在氧化之前，涂层由（含少量Al 5 Fe 2和Al 13 Fe 4的富Al面漆）/（富含Al 13 Fe 4的含Al 13 Fe 4的合金层）/（Al 5 Fe含有少量Al 9 Cr 4的2合金层从表面析出。在700–900°C的温度下进行20–100小时的氧化过程中，Al向内扩散，基底元素向外迁移，从而使涂层变宽和变软，并且还将（高Al）-Fe金属间化合物转变为（低Al）-Fe金属间化合物。涂层中的相在氧化过程中按如下方式逐渐转变： （富铝面漆）/（富Al 5 Fe 2，含Al 13 Fe 4的合金层）/（Al 5 Fe 2合金层）→（α-Al2 O 3鳞片）/（Al 13 Fe 4-富含Al 5 Fe 2的层）/（Al 5 Fe 2层）/（AlFe中间层）→（α-Al2 O 3鳞片）/（富含AlFe–的Al 5 Fe 2层）/（AlFe层）/（AlFe 3层））→（（α-Al2 O 3，Fe 2 O 3）-混合鳞）/（AlFe 3层）/（Fe（Al）层）。随着氧化的进行，水垢从α-Al2 O 3变为（α-Al2 O 3，Fe 2 O 3）混合物，从而提供了必要的抗氧化性。
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