Grain refining efficiency and microstructure of Al-Ti-C-RE master alloy

Al-Ti-C-RE master alloy has been successfully prepared by reaction of K2TiF6 salt, graphite powder and rare earth (RE) with Al. The microstructure of the alloy was characterized by optical microscopy, X-ray diffraction, scanning electron microscopy equipped with energy-dispersive spectrometry. The results show the microstructure of Al-Ti-C-RE alloy is composed of alpha-Al, lath-shaped TiAl3, granular TiC, and blocky or rim Ti2Al20Ce. Compared with the Al-Ti-C master alloy, the addition of RE modifies the morphology of TiAl3 phase, accelerates the formation of TiC. Al-Ti-C-RE alloy was used for grain refinement studies on commercial pure aluminum. An excellent grain refining performance was obtained when the addition level of Al-Ti-C-RE reaches to 0.5 wt%. The refinement mechanism of Al-Ti-C-RE has also been discussed. (C) 2010 Elsevier B.V. All rights reserved.