Influence of Ti/C mass ratio on the microstructure of Al-Ti-C master alloy and refinement effect on pure aluminum

Abstract Al-Ti-C master alloys with different Ti/C mass ratios were fabricated by self-propagating high-temperature synthesis (SHS).Besides, the effect of Ti/C mass ratio on the microstructure of SHS products and its effect on the grain refinement of industrial pure aluminum were also investigated. The results indicated that the product with Ti/C mass ratio of 4:1 is mainly composed of TiC particles with average size of 0.81 μm, and there is only a small amount of rod-shaped Al3Ti in the sample. When the Ti/C mass ratio is increased to more than 10:1, the rod-shaped Al3Ti is the main product in master alloy, which has the most obvious effect on the refinement of pure aluminum. When the addition amount is 3wt.%, the average grain size decreased to about 191 μm. The Al-Ti-C master alloy with Ti/C mass ratio of 4:1 has better anti refining degradation performance. When add 1.2% of the above master alloy to pure aluminum, holding time 60min, the macroscopic grains of industrial pure aluminum is more uniform and finer, with an average grain size of 324µm. The results indicate that the morphology of TiC particles in the product changes from regular sphere to polyhedron with the increases of mass ratio of Ti/C, the average size of TiC particles increases, and the rod-shaped Al3Ti changes from thick rod to thin rod, the average size of rod-shaped Al3Ti decreases.