Grain refinement of A356 alloy by Al–Ti–B–C master alloy and its effect on mechanical properties

A new Al–3Ti–1B–0.2C master alloy with uniform microstructure was prepared using a melt reaction method in this study. In the master alloy, TiB2 particles exhibit hierarchical dendritic morphology, while TiC particles doped with a trace amount of B show a polyhedral morphology. The grain refining performance of the master alloy on A356 alloy has also been investigated. It is found that the addition of 0.2 wt.% Al–3Ti–1B–0.2C master alloy can induce very effective grain refinement of the A356 alloy. The average grain size of α-Al is reduced to 167 ± 8 μm from about 1570 μm and the grain refining efficiency does not fade obviously within 60 min. Therefore, the mechanical properties of the A356 alloy have been improved obviously by the addition of the Al–3Ti–1B–0.2C master alloy, including the ultimate tensile strength, yield strength and elongation.

► Al–3Ti–1B–0.2C master alloy with a uniform microstructure was prepared. ► The nucleating efficiency of the particles has been improved. ► The master alloy behaves a good grain refining performance on A356 alloy. ► Mechanical properties of A356 alloy have been obviously improved.