Macrosegregation in high-pressure die-cast AM60 alloy

Macrosegration is known to occur in the vicinity of cast surfaces in Al and other nonferrous alloy castings under certain conditions and has been well documented, but it has not been investigated in high-pressure die-cast Mg-alloys. Solidification gives rise to transport of interdendritic liquid in order to feed shrinkage, which leads to a solute-rich region close to the cast surface, commonly called inverse segregation. This contribution presents an experimental metallographic evidence of inverse macrosegregation in a high-pressure die-cast AM60B Mg-alloy and the effects of process parameters on the extent of inverse segregation. The combination of the process parameters that leads to low levels of micro-porosity facilitates the occurrence of inverse macrosegregation in this alloy.