Ti/Al2O3 interfacial diffusion: Kinetic equation for growth of reaction layer and formation mechanism

Ti/Al2O3 composites are prepared by vacuum hot-pressing sintering in order to study the elements diffusion and formation of the reaction layer at the interfaces. The results indicate that the forming process of the reaction layer can be separated into three stages, and the thickness of the interfacial layer is greatly related to the sintering temperature and holding time. By calculating, the kinetic equation for the growth of the thickness is expressed as d = 1.2864 x 10(3)exp(-(153:1 x 10(3))/RT)t(0.96). When temperature is above 1250 degrees C, Al element has more powerful diffusion ability than Ti, so reaction layer mainly composed of TiAl and Ti3Al is formed at the side of Ti zone. In the case of Al2O3 phase, Al ions dissolve in the Ti phase substitutionally and migrate by exchanging with vacancies, which is in contrast with the direct interstitial mechanism of Ti and O ions. (C) 2015 Elsevier B.V. All rights reserved.