Structure and refinement performance of Al-5Ti-0.2C master alloy produced via an improved self propagating synthesis approach

Abstract

When Al-Ti-C master alloys are produced via the conventional Self-propagating High-temperature Synthesis (SHS), the reduction of production temperature below 1523 K leads to the drastic deterioration of the refiner efficacy. In the present work, a simple yet effective way to improve the combustion process for low TiC-containing refiners is proposed. The SHS reaction was performed to obtain Al-10TiC slurry first, which subsequently was mixed with Al-Ti melt to obtain Al-5Ti-0.2C master alloy. By means of the proposed method, the process temperature was lowered to 1323 K. According to the results, in the case of improved SHS approach, the Al temperature after the onset of reaction increases by 90-100 K more than in the case of conventional preparation route, providing better kinetic conditions for TiC formation. As a result, at 1323 K production temperature, the average carbide size increases by 100% as compared to the conventionally produced refiner, which is claimed to be a reason for the improved refining performance of master alloy.