Mo-enhanced chemical stability of TiC nanoparticles in molten Al

Abstract

TiC nanoparticle is an effective reinforcement for Al alloys. However, the inevitable reaction between Al and TiC below 780 °C is problematic. Successful solidification processing of the Al-TiC system under industrially benign temperatures is needed. To achieve this, given the lower surface reaction diffusivity of Mo in Al, the effect of Mo addition (0.5 wt%) on the chemical stability of Al-TiC at 750 °C is studied. The microstructures and phase compositions after adding Mo have been compared to the Mo-free material. It shows a clear difference in mechanical properties (i.e., microhardness and compression strength) and electrical conductivity between Al-TiC and Al-Mo-TiC during the reaction. Moreover, in situ XRD scanning was used to determine the reaction rate between molten Al and TiC. The results support the positive effects of Mo addition in suppressing Al-TiC reaction and Al3Ti generation at 750 °C. This finding would be of significance to developing Al-TiC nanocomposites with higher chemical stability under a wider processing temperature.