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利用热场发射电镜研究AISI-304奥氏体不锈钢表面在用粉末包埋法热扩散处理获得的渗硅层的微观组织和精细结构。结果表明,在1050℃扩散处理6h,γ相不锈钢的渗硅层厚度可达60μm以上,渗硅层组织由高硅表面和α相扩散区组成,在α相扩散层中由表及里出现了不同形貌的类调幅组织,由表及里逐渐细化,其形貌从交叉织纹状到正交片状和交叉短杆状过渡。在扩散层中部为单一的砌块状DO3(Fe3Si型)有序转变产物,深部为纳米级细晶粒,至γ相基体前晶粒更加细小。微观成分分析表明,渗硅层的微观结构与硅的浓度梯度密切相关。
The microstructure and fine structure of the siliconized layer obtained on the surface of AISI-304 austenitic stainless steel by thermal diffusion with powder embedding method were studied by thermal field emission electron microscope. The results show that the thickness of the infiltrated silicon layer in γ-phase stainless steel can reach over 60μm at 1050 ℃ for 6h, and the microstructure of the siliconized layer consists of the high-silicon surface and the α-phase diffused region. In the α-phase diffused layer, Different types of amplitude modulation organization, gradually thinning from the table, the shape of the cross from the weave to the orthogonal sheet and cross short rod-shaped transition. In the central part of the diffusion layer, there is a single block-like DO3 (Fe3Si type) ordered transformation product, with nano-scale fine grains in the deep part and smaller grains before the γ-phase matrix. Micro-composition analysis shows that the microstructure of the siliconized layer is closely related to the concentration gradient of silicon.