SEM In Situ Investigation of the Effects of Ca and Sr Additions on Cracking in Cast AZ91D Alloys at Different Temperatures

We studied the effects of the Ca and Sr additions on the microstructure and the cracking process of magnesium alloys with in-situ scanning electron microscope (SEM) images. We found that the Ca addition is not only able to refine the Mg17Al12 phase but also form a new Al2Ca phase, which lead to improved ductile of cast magnesium alloys at elevated temperature. The MgAlCaSr phase can be improved the hot resistance. However, the number of cracks per unit area increases with increasing Ca addition.