Grain refinement of an AZ63B magnesium alloy by an Al - 1C master alloy

In order to develop a refiner of Mg – Al alloys, an Al – 1C (in wt.%) master alloy was synthesized using a casting method. The microstructure and grain-refining performance of the Al – 1C master alloy were investigated using X-ray diffraction (XRD), electron probe microanalysis (EPMA) and a grain-refining test. The microstructure of the Al – 1C master alloy is composed of α-Al solid solution, Al4C3 particles, and graphite phases. After grain refinement of AZ63B alloy by the Al – 1C master alloy, the mean grain size reached a limit when 2 wt.% Al – C master alloy was added at 800 °C and held for 20 min in the melt before casting. The minimum mean grain size is approximately 48 lm at the one-half radius of the ingot and is about 17 % of that of the unrefined alloy. The Al – 1C master alloy results in better grain refinement than C2Cl6 and MgCO3 carbon-containing refiners.