Effect of Calcium and Strontium on Microstructure of AZ31 Wrought Magnesium Alloys
AZ31 wrought alloys at as-cast state with different microcontent calcium and strontium was studied by optical microscopy, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The study shows that the primary dendrite spacing and the secondary dendrite arm spacing can be refined significantly by Ca or Sr element. At 0.5wt.% Sr and 1.8wt.% Ca, the best refinement effect is fulfilled, its primary dendrite spacing and secondary dendrite arm spacing decreased from 292μm to 87μm. The Al4Sr intermetallic compound is observed at grain boundaries When Sr was added. The Al4Sr disappears after Ca added, a new ternary intermetallic compound (Mg, Al)2Ca presents. The addition of Sr and Ca can cause microhardness increasing.
Yafang Han, Fusheng Pan, Jianmao Tang, Chungen Zhou
Z. Q. Zhu et al., "Effect of Calcium and Strontium on Microstructure of AZ31 Wrought Magnesium Alloys", Materials Science Forum, Vol. 686, pp. 30-39, 2011