Grain Refining Efficiency of SHS Al-Ti-B-C Master Alloy for Pure Aluminum and Its Effect on Mechanical Properties

A new Al-5Ti-0.75B-0.2C master alloy was successfully prepared by self-propagating high-temperature (SHS) reaction from an Al-Ti-B₄C system with molten Al. Microstructure and phase characterization of the prepared Al-5Ti-0.75B-0.2C master alloy show that the nearly spherical TiC particles, hexagonal or rectangular TiB₂ particles, and block-like TiAl3 particles distribute uniformly in the aluminum matrix. Grain refining test on commercial pure aluminum indicates that Al-5Ti-0.75B-0.2C master alloy exhibits a better grain refining performance than Al-5Ti-1B master alloy. By addition of 0.2 wt% Al-5Ti-0.75B-0.2C master alloy, the average grain size of α-Al can be effectively refined to 160 ± 5 μm from about 3000 μm, and the tensile strength and elongation are increased by about 20% and 14.1% due to the grain refinement.