Interactions of particles with solidifying front in Al2O3P/Al-Si composites
(College of Materials Science and Engineering,Huazhong University of Science and Technology, Wuhan 430074, P.R. China)
Abstract: The behavior of ceramic particles at the solid/liquid interface and the distribution of particles in metallic matrix composites was studied with a zone unidirectional solidification method. Two kinds of partice dispersed composites, Al2O3P/Al-12.6%Si-Sr and Al2O3P/Al-12.6%Si-Sr-Ca containing Al2O3 particles in volume fraction 2%~5% were used. In the Al2O3P/Al-Si-Sr composites, the particles were pushed by the solidifying front, and did not uniformly distribute in the solid. But in the Al2O3P/Al-Si-Sr-Ca composites, the particles were engulfed by the solidifying front and uniformly distributed in the solid. The particles engulfing into the solid was realized only by Sr and Ca addition at the same time. As the interfacial energy between solid and particle was decreased in this case, the Al2O3 particles acted as the substrates of heterogeneous nucleation for the Si phases, which made the particles to be engulfed.
Key words: metallic matrix composites; solidification; particle size distribution