Spray forming of 2014-Al alloy based composites with injection of SiC particulates

Abstract

Aluminium alloy (AA2014) based metal matrix composites were produced by spray atomization and co-deposition. The mass median diameter and mass flow rate of SiC were varied between 6 and 58 mum and between 10 and 30 wt.% of the melt flow rate, respectively. Microstructures of deposits and overspray powder particles were examined. Porosity and SiC content were measured at different positions in the preform. The fraction of SiC particulates incorporated in the preform varies between 4 and 11 vol.%, which is caused by the low compaction efficiency lying within the range of 30 to 50 % of injected secondary particulates. Porosity is observed to increase with increase in deposited SiC content. Optical microscopy shows a uniform distribution of particles in the microstructure. Microstructural examination of overspray powder particles shows that the basic reason for the incorporation of smaller particles is the collision between reinforcement particles and the liquid droplets during flight. The results are presented and discussed in light of process parameters used.