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 = 70.2 + 1190.8/ 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 = 0.5,1, 5, 12, 20 K) compared to Ti and TiCN refiners.