Microstructures and grain refinement performance of rapidly solidified Al-Ti-C master alloys

In the present work, the microstructures and grain refining performance of melt-spun Al-3.5Ti-0.15C. Al-5Ti-0.3C and Al-10Ti-1C (in wt.%) alloys have been investigated, using X-ray diffraction (XRD), scanning electron microscopy (SEM), and grain refining tests. All three types of ingot-like alloys contain coarse slablike TiAl3 and fine TiC particles. The microstructures of melt-spun Al-3.5Ti-0.15C and Al-5Ti-0.3C alloys are composed of spherical or near-spherical dispersed TiC particles and alpha-Al supersaturated solid solution, while melt-spun Al-10Ti-1C alloy consists of small blocky TiAl3, spherical or near-spherical TiC particles and alpha-Al solid solution. Furthermore, most of the TiAl3 and TiC particles are distributed in the edge zone of the chill surface of the rapidly solidified alloy ribbons. Rapid solidification process (RSP) does not improve the grain refinement performance of Al-Ti-C master alloys. The reasons for the formation of microstructures and the grain refining performance of melt-spun Al-Ti-C master alloys have also been discussed. (C) 2002 Elsevier Science B.V. All rights reserved.