Non-parabolic Al3Ti intermetallic layer growth on aluminum-titanium interface at low annealing temperatures

Abstract Intermetallic compound (IMC) layer growth at dissimilar metal interfaces, controlled by diffusion, usually follows a parabolic law. However, in the present study, the growth of Al3Ti layer on the Al-Ti interface at a low annealing temperature (TA, 500 °C) obviously didn’t follow a parabolic law. A very long incubation stage of Al3Ti layer growth was observed in the Al-Ti diffusion couple annealed at 500 °C. Residual oxide layers and an oxygen rich layer were experimentally observed on Al-Ti and Al3Ti-Ti interface regions using high resolution STEM-EDS. The very long incubation stage is probably caused by the oxide layers and the oxygen rich layer on the interface region, which act as a diffusion barrier and as a source of oxygen atoms. The length of the incubation stage became shorter and even unobservable with increasing temperature probably due to the higher reaction rate between titanium oxides and aluminum at higher temperatures.