SiC/Ti6Al4V复合材料界面反应扩散系数和微观扩散机理

采用三元体系半无限扩散偶的高斯方法,求解了SiC/Ti6AL4V复合材料界面反应层中相关元素的扩散系数,计算的浓度分布和实测值一致.碳原子通过反应层的扩散服从间隙扩散机制,硅原子的扩散为空位扩散机制.由于碳扩散的振动能最低并且跃迁距离最短,而供硅扩散的空位不足,碳和硅在反应产物TiCx中具有最小的内禀扩散系数,分别为8.9403×10-16和4.7747×10-16 m2·s-1.研究表明,在SiC/Ti6AL4V复合材料界面反应的过程中,反应元素通过反应层TiCx的扩散是一个主要的控制步骤.

Interfacial Reaction Diffusion Coefficients and Micro-Diffusion Mechanism in SiC/Ti6A14V Composite

The diffusion coefficients of the relative reactive elements in interfacial reaction layer of SiC/Ti6A14V composite were solved by use of Guass method in a semi-infinite diffusion couple for ternary systems, and the concentration distribution of diffusion elements calculated was well fitted to the measurements. C atoms diffuse through the reaction layer by interstitial diffusion mechanism, while Si atoms diffuse through the reaction layer by vacancy diffusion mechanism. C and Si atoms have the minimum intrinsic diffusion coefficients in TiCx layer, which are 8.9403×10-16 and 4.7747×10-16 m2·s-1, respectively, because of the lowest molecular vibrancy energy and transition distance for C atoms and the insufficient vacancy for Si atoms. The reactive element diffusing through the TiCx layer is a dominant determining step in interfacial reaction progress of SiC/Ti6Al4V composite.