Particle size versus grain size relation in the sprayformed Al-18Si composites

Abstract

Various hypereutectic Al-18Si-X composites with different average Si particle sizes ranging from 0.2 similar to 30 mu m were produced by varying process parameters of spray forming. The effect of the Si particle size in determining the matrix grain size was investigated in order to design the optimum process for producing hypereutectic Al-18Si-X composites with fine microstructures. The experimental results suggested that the Si particle size greater than 2 mu m is desirable for retarding the grain coarsening during subsequent forming processes, resulting in the fine microstructure. The observed results on the coarsening behavior of grains during spray-forming were analyzed from the free energy viewpoint.