The grain refinement of aluminium by a new as-cast Al–Ti–TiCN composite

Abstract

A new type of composite refiner Ti/TiCN is prepared by loading submicron-TiCN particles onto Ti micron-particles and added to industrial pure aluminium. Refining mechanism has been characterised in detail by optical microscopy, scanning electron microscopy and transmission electron microscopy coupled with energy disperse X-ray spectra. These experimental results show that Ti/TiCN inoculation is more effective in refining pure aluminium than Ti and TiCN added separately. The relationship between grain size and growth restriction factors of aluminium matrix containing Ti/TiCN refiner is d\u2009=\u200970.2\u2009+\u20091190.8/Q. According to the free growth theory, aluminium matrix with Ti/TiCN inoculation has the largest solidification driving force to promote grain nucleation under the same growth restriction factors (Q\u2009=\u20090.5,1, 5, 12, 20\u2009K) compared to Ti and TiCN refiners.