Effect of TiAl₃ particles size and distribution on their settling and dissolution behaviour in aluminium

Abstract

The effect of TiAl₃ particle size and distribution on their settling and dissolution behaviour in molten aluminium during grain refinement has been studied. For this purpose Al-5Ti master alloys containing blocky TiAl₃ particles of different size and distribution are synthesised at reaction temperatures 750, 800 and 850 °C for 60 min and used for grain refinement. The extent of fading and the recovery due to stirring is calculated from the measured grain size and used to judge the dissolution and settling behaviour of TiAl₃ in molten Al, which is greatly attributed to its size and distribution in Al-5Ti master alloy. Fine TiAl₃ particle dissolve faster in the melt and cause fading. Larger size TiAl₃ particles exist for longer time in molten Al and act as a nucleating site even when added in hypoperitectic concentration (0.05 wt% Ti).