Growth of Al_8Mn_5 Intermetallic in AZ91

摘要

Al_8Mn_5 is crucial for impurity control and corrosion resistance of AZ91. We study the growth morphology of primary and eutectic Al_8Mn_5 after the equiaxed solidification of AZ91 cooled at ～1 K/s. Primary Al_8Mn_5 grew as ～10 μm equiaxed faceted crystals with multiple growth facets. The eutectic Al_8Mn_5 grew with a complex faceted morphology ranging from rod to sheet and folded plate-like, often with growth steps on the largest facets. The results are compared with the AZ91 solidification path predicted by PanDat with the PanMg8 database.