Effect of hafnium carbide on the grain refinement of Mg-3 wt.% Al alloy

This study investigates how different amounts of hafnium carbide (HfC) powder affect the grain refinement of Mg-3 wt.% Al alloys. Even though HfC and Mg have a similar crystallography, the use of HfC powder is not a very effective means of refining pure magnesium with typical columnar grains. However, Mg-3 wt.% Al alloy can be successfully refined by the addition of HfC due to the in situ formation of Al4C3. The addition of 0.7 wt.% of HfC into Mg-3 wt.% Al alloy leads to the smallest grain size, and its average grain size is refined from 365 μm to 145 μm.