定向凝固下Ti-48Al合金与不同氧化物铸型涂层界面反应的研究

Interaction Between the Ti-48Al Alloy and Ceramic Materials During the Solidification Process

摘要:

通过SEM、EDS以及XRD等检测方法对Ti-48Al合金分别与Al2O3、Y2O3、ZrO2铸型涂层的界面反应处的微观组织、元素分布以及界面处的相组成等进行检测；同时结合对界面处的硬度测量，得到界面反应层厚度。结果表明，合金熔体与不同铸型涂层均发生了界面反应。铸型涂层材料不同，界面反应剧烈程度也不同。反应过程中在熔体和扩散元素的冲击下，物理侵蚀和化学反应同时存在形成了反应层，反应的强弱则与涂层材料有关。更值得注意的是，对钛铝合金与铸型涂层的热力学性质进行了计算。研究还表明，熔体在界面处的反应层主要由涂层材料的脱落扩散程度控制，涂层中的元素尤其是O元素的扩散是控制界面反应进程的重要因素。

Abstract:

The effect of Al2O3, Y2O3 and ZrO2 coating materials to the Ti-48Al alloys on the metal-coating interface, alloy chemical composition and microstructure is evaluated by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction analysis, respectively. Microhardness variation from the surface to the inside of the samples was compared. The results indicate that inordinate interaction occurred at the interface between the coating and the melt. The crucible layer was found to suffer chemical dissolution and some physical erosion by the molten alloy and the extent of that dissolution, depend partly on the coating material. Additionally, The thermodynamics of the TiAl/Oxide reactions have been studied, and the main mechanism responsible for the contamination of the directional solidification samples is diffusion controlled dissolution of the coatings in the melt which leads to an increase of oxygen content in the matrix.