Abstract

The microstructure and mechanical properties of spray formed and hot-pressed Al-35Si alloy was studied and compared with as cast alloy. The microstructures of spray deposited, hot pressed and as cast alloys were investigated by optical microscopy, scanning electron microscopy techniques. The microstructure of spray deposited alloy showed a homogeneous distribution of fine primary silicon, eutectic silicon phases in the equiaxed Al-matrix. The microstructural refinement was further increased by hot compression. The microstructure of as-cast alloy composed of coarse plate-like primary Si particles and needle/fiber form of eutectic Si randomly distributed in the Al dendritic matrix. Room temperature hardness and tensile strength of spray formed, hot compressed alloy showed considerable increase in their strength and ductility over that of as cast alloy. The improvement in hardness, mechanical properties of spray deposited alloy is discussed in light of the microstructural refinement induced during spray deposition and hot-pressing processes.

Keywords: Microstructure; Hardness; Tensile strength; Spray deposition process