Effect of B/C ratio on the microstructure and grain refining efficiency of Al–Ti–C–B master alloy

A series of Al–Ti–C–B master alloys with different B/C ratios were prepared in the present study. It was found that with the increase of B/C ratio, the microstructure of Al–Ti–C–B was improved firstly and then became agglomerated at a very high B/C ratio. Furthermore, the grain refining performance of Al–Ti–C–B also varied with the increase of B/C ratio. The experimental results show that Al–Ti–C–B master alloy presents both a dispersive microstructure and a high grain refining efficiency at an optimum B/C ratio about 1/1. It is supposed that the improvement of Al–5Ti–0.25C–0.25B master alloy can be attributed to the high efficiency TiCxBy particles and a certain amount of TiB2 particles.

Research highlights▶ Al–Ti–C–B master alloy presents both a dispersive microstructure and a high grain refining efficiency at an optimum B/C ratio about 1/1. ▶ The B element doped in TiCxBy particles can greatly improve the grain refining ability for α-Al grains. ▶ A proper B/C ratio in the Al–Ti–C–B master alloy is important for the formation of the high efficiency nucleating particles of TiCxBy.