Development of Al-Ti-C grain refiners and study of their grain refining efficiency on Al and Al-7Si alloy

Al-5Ti-0.8C and Al-5Ti-1.2C master alloys have been successfully prepared by reaction of K2TiF6 salt and graphite powder with molten Al. While the Al-5Ti-0.8C consists of some TiAl3 particles in addition to TiC particles in the Al matrix, the Al-5Ti-1.2C master alloy revealed the presence of only TiC particles. The grain refining efficiency of these two master alloys has been compared with that of the conventional Al-5Ti-1B master alloy on Al and Al-7Si alloy at different addition levels. Al-5Ti-1.2C master alloy was found to be the most efficient grain refiner for Al amongst the grain refiners studied. Even in case of Al-7Si alloy, the Al-5Ti-0.8C and Al-5Ti-1.2C master alloys performed better than conventional Al-5Ti-1B master alloy. However, the Al-5Ti-1.2C master alloy shows poor response to grain refinement in Al-7Si alloy at higher addition levels than the Al-5Ti-0.8C master alloy, indicating poisoning.