Surface modification of aluminum with green compact powder metallurgy Inconel-aluminum tool in EDM

The present work attempts to modify the surface characteristics of Al-7075 alloy using powder metallurgy (PM) green compact tool in electric discharge machining (EDM). Al-7075 alloy has high strength but possesses poor tribological properties due to its lower hardness. So, Inconel 718 powder, having high hardness and corrosion resistance, and Al powder which acts as binder material is mixed for the preparation of PM green compacts. The tool material is then deposited onto the workpiece by EDM process to modify its surface. Pulse on-time and current have been varied and their influence on the characteristics of the workpiece surface are investigated by evaluating material transfer rate, tool wear rate and surface roughness of the deposition. The surface characteristics of the deposited layer are evaluated by optical microscopy and scanning electron microscopy analyses, wherein the formation of recast layer, globules, redeposition and cracks is depicted. X-ray diffraction and energy dispersive X-ray analyses substantiate the existence of tool material and carbides, which confirms the successful deposition of Inconel on Al workpiece. The deposited layer exhibits an increase in micro-hardness by 1.5-2.5 times as compared to the base material. This confirms the effectiveness of depositing Inconel on the surface of Al workpiece using EDM.