Fluidity and microstructure evolution of Al-12%B4C composites containing magnesium

Abstract

The influence of 0.5% magnesium addition on the fluidity evolution and microstructure of aluminum and Al-12%B4C composites was investigated. It was observed that the magnesium addition reduced the fluidity of aluminum and the Al-B4C composites. Moreover, magnesium promoted the interfacial reactions between liquid aluminum and B4C in the Al-B4C composites. An adequate Ti addition in the composites could effectively limit the impact of magnesium on the interfacial reactions and significantly improve the fluidity by forming a dense TiB2 protective layer on the B4C particle surface. It was also found that a part of magnesium is consumed in the reaction product, which resulted in the reduction of magnesium available in the matrix. The effects of magnesium and titanium on the fluidity, interfacial reactions and magnesium redistribution were discussed. © 2011 The Japan Institute of Light Metals.