Influence of C/Ti stoichiometry in TiCx on the grain refinement efficiency of Al-Ti-C master alloy

TiCx contained Al-Ti-C is a kind of grain refiner for Al alloys. In this work, the influence of C/Ti stoichiometry, i.e. the x value in TiCx on grain refinement efficiency was investigated. TiCx particles have been obtained in five Al-5Ti-mC (m= 0.1, 0.5, 0.8, 1, 1.25) master alloys and the x values were measured to be 0.72, 0.75, 0.79, 0.81and 0.8, respectively. It was found that the refinement performance of the master alloys had a close relationship with the x value of TiCx. The Al-5Ti-mC alloy with lower-x TiCx shows better refinement efficiency and anti-fading capability. It is supposed that TiCx particles with lower x are more preferred to release Ti atoms during nucleating process and have a better Ti-absorbing capability. This contributes to the Ti-rich zone formation at TiCx/melt interface, thus enhancing the refinement and anti-fading capability. (C) 2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.