Grain Refining Performance of Al-B Master Alloys with Different Microstructures on Al-7Si Alloy

摘要

The improved halide salt route has been employed to produce A1-3B master alloys with different micro-structures. The microstructural features of AlB_2 particles exhibited different impacts on the grain refining response of Al-7Si alloy, evolving with the holding time after inoculation. Large blocky A1B_2 particles suffer from an intense fading effect while strip-like particles are not effective enough at the 0.005 wt% B addition level. Among the various A1-3B master alloys, sample 1 containing fine, blocky A1B_2 particles was revealed to be the most efficient in refining Al-7Si alloy. With inoculation of only 0.005%B of such alloy, the final grain size of Al-7Si alloy can reach 238 urn. Its grain refining efficiency was more or less retained for holding times up to 60 min.