目的 研究Si对Fe-18%Cr-3%B合金高温抗氧化性能的影响，并开发新型抗氧化轧辊材料。方法 采用定向凝固技术制备出Si质量分数分别为0.0%、1.0%、2.0%、3.0%的Fe-Cr-B定向凝固合金，并用增重法表征合金的氧化动力学，通过SEM、XRD等手段分析定向合金氧化膜表面和截面形貌、结构和物相组成，并评价Si对定向合金抗氧化性能的作用。结果 Si的加入明显细化了定向凝固Fe-Cr-B合金的组织，有利于合金中硬质相M2B硼化物的定向生长。氧化结果表明，经800 ℃氧化100 h后，Si的加入可使合金氧化速率从0.052 28 g/(m².h)降至0.009 28 g/(m².h)，抗氧化性能提升5倍以上。Si的加入使定向合金表面氧化膜变得光滑平整、致密连续且无开裂和剥落。表面膜结构分析表明，该定向合金氧化膜从合金基体到表面依次为Cr2O3、FeCr2O4、Fe3O4尖晶石和最外层的Fe2O3复合氧化物，而Si的加入促进了最内层SiO2氧化膜的形成，该层呈连续曲折形态存在于定向合金与Cr2O3的界面。同时，定向合金中取向排列的M2B硬质相与内氧化层SiO2呈现出“嵌入式”的嵌合界面，改变了界面结合形态和内界面结构，显著提高了复合氧化膜与定向合金界面的附着力。定向合金的氧化过程中，相对粗大的初生硼化物失效主要源于初生硼化物的剥落与氧内扩散诱致M2B开裂。结论 Si显著提高定向Fe-Cr-B合金的抗氧化性，主要机制为Si促进内氧化层SiO2的形成，并导致“互嵌入式”的SiO2/M2B双向嵌合界面结构的产生，这种氧化膜/合金界面“取向性互嵌型钉扎膜结构”可有效提高膜基界面附着力。

The aims is to study the effect of Si on the high temperature oxidation resistance of Fe-18wt.%Cr-3wt.%B alloy and develop a new type oxidation-resistant roll material. Fe-Cr-B directional solidification alloys with Si content of 0.0wt.%, 1.0wt.%, 2.0wt.%, and 3.0wt.% were prepared by directional solidification technology and the oxidation kinetics of the alloys were characterized by the weight gain method. Analyze the surface and cross-sectional morphology, structure and phase composition of the oriented alloy oxide film by means of SEM, XRD and other means and evaluate the effect of Si on the oxidation resistance of the oriented alloy. The addition of Si significantly refines the structure of the directionally solidified Fe-Cr-B alloy, which is beneficial to the directional growth of the hard phase M2B boride in the alloy. The oxidation results show that the addition of Si can reduce the oxidation rate of the alloy from 0.052 28 g/(m2.h) to 0.009 28 g/(m2.h) after being oxidized at 800 ℃ for 100 h, and the oxidation resistance is increased by more than 5 times. The addition of Si makes the surface oxide film of the oriented alloy smooth, compact and continuous without cracking and peeling. The analysis of the surface film structure shows that the oriented alloy oxide film is composed of Cr2O3, FeCr2O4, Fe3O4 spinel and the outermost Fe2O3 composite oxide from the alloy matrix to the surface. The addition of Si promotes the formation of the innermost SiO2 oxide film. The layer is in a continuous tortuous form at the interface between the oriented alloy and Cr2O3. At the same time, the oriented M2B hard phase and the internal oxide layer SiO2 in the oriented alloy present an “embedded” intercalation interface, which changes the interface bonding morphology and internal interface structure, and significantly improves the adhesion between the composite oxide film and the oriented alloy interface force. The failure of relatively coarse primary borides in the oxidation process of oriented alloys is mainly caused by the spalling of primary borides and the internal diffusion of oxygen inducing M2B cracking. Si significantly improves the oxidation resistance of the oriented Fe-Cr-B alloy. The main mechanism is that Si promotes the formation of the internal oxide layer SiO2 and leads to the production of the "inter-embedded" SiO2/M2B bidirectional intercalation structure. This film/alloy interface which is composed by “oriented inter-embedded pinned film structure” can effectively improve the adhesion of the film/matrix interface.