Grain refinement response of LM25 alloy towards Al–Ti–C and Al–Ti–B grain refiners

Abstract

The grain refining response of LM25 (Al–7Si–0.35Mg) alloy has been studied with the newly made Al–5Ti–0.8C and Al–5Ti–1.2C master alloys which have been successfully prepared in the laboratory by reaction of K 2TiF 6 salt and graphite powder with Al. The results have been compared with the grain refining efficiency of Al–3B, Al–1Ti–3B and Al–5Ti–1B master alloys on LM25 alloy at different addition levels. The results show that the grain refining efficiency of even lowest addition level (0.1 wt.%) of both Al–5Ti–0.8C and Al–5Ti–1.2C master alloys are equivalent to the 1.0 wt.% addition levels of Al–1Ti–3B and better than 1.0 wt.% of Al–3B master alloy. At higher addition levels of Al–5Ti–0.8C and Al–5Ti–1.2C master alloys exhibits fading in grain structure on longer holding due to agglomeration of TiC particles and poisoning of Si.