Influence of carbon source on the microstructure of Al-Ti-C master alloy and its grain refining efficiency

A new kind of Al-5Ti-0.3C master alloy with a uniform microstructure was prepared by using Al-5C alloy as a carbon source in this study. In the master alloy, TiC particles exhibit hexagonal platelet and macroporous morphologies, distributing homogeneously in the aluminum matrix. It is supposed that TiC particles are synthesized by the reaction between dissolved Ti and Al4C3. The grain refining performance of the master alloy on commercial pure aluminum was investigated. The average grain size of α-Al can be reduced from 3300 μm to 178 μm with the addition of 0.2 wt.% of the prepared Al-5Ti-0.3C master alloy. Besides, the grain refining efficiency is stable and does not fade within 30 min.