Effects of mischmetal modification

misch metal plus phosphorus modification and melt superheating treatment on microstructure and properties of in-situ 18Mg2Si/Al composites were investigated.The results show that the primary Mg2 Si in 18Mg2Si/Al composites presents coarse polygonal shapes or dendritic shapes with the average grain size of 65.3μm and uneven distribution in condition of unmodification.After modification treatment

the primary Mg2 Si is refined to some extent

where the size of primary Mg2 Si reaches 15μm after mischmetal plus phosphorus modification

and the eutectic Mg2 Si becomes spheroidization.In addition

the size of primary Mg2 Si reaches 13μm after melt superheating treatment

and the eutectic Mg2 Si exhibits sinewy.After mischmetal modification

misch metal plus phosphorus modification

and melt superheating treatment

the tensile strength and elongation of the insitu composites are improved to some extent.