Thermo-mechanical treatment of Al-5Ti-1B and Al-5Ti master alloy on its grain refining performance on aluminium

摘要

Al-5Ti-1B and Al-5Ti master alloys in as cast, extruded and rolled conditions were studied for their grain refining performance on aluminium (Al). The Al-5Ti-1B and Al-5Ti master alloys were prepared by the reaction of K_2TiF_6, KBF_4 and K_2TiF_6 respectively with molten Al. The performance of as cast and thermo-mechanically treated master alloys have been studied in deytaik and results showed that thermo-mechanically treated master alloys showed improved grain refining results as compared to as cast master alloys. This is due to the formation of more number of TiAl_3 particles that were formed during rolling and extrusion. In both the processes, the mean particle size of TiAl_3 decreased with increase in the reduction level of rolling. Moreover, the morphology ofTiAl_3 in as cast condition was observed as plate like and after thermo-mechanical treatment, the morphology has been changed to blocky type and the latter was considered to be effective nucleating sites during solidification of Al.