Application of powder metallurgy-processed Al-Cu-CNT composite electrodes for surface modification of inconel 718 using EDM

Surface modification of workpiece through Electro-Discharge Machining (EDM), particularly in terms of elemental composition, microstructure, and properties, is a growing area of research. Inconel is hard to cut because of its high strength, severe strain hardening, and cutting tool wear. While researchers have focused on Inconel's electro-discharge machining and optimization, its surface modification remains underexplored. In this work, Inconel 718 machined with five powder metallurgy (PM) processed Aluminium (Al) metal matrix composite electrodes with 5 Weight % of Copper (Cu) and varying amounts (0–1.5 volume %) of carbon nanotubes (CNT) named as PM-Al, PM-Al-5Cu, PM-Al-5Cu-0.5CNT, PM-Al-5Cu-1.0CNT, PM-Al-5Cu-1.5CNT. The results were compared with cast Cu electrodes. The PM-processed electrodes exhibited a higher material transfer to the workpiece than the cast-Cu electrode. A significant increase of transferred materials (carbon, Al, Cu) and a decrease of Inconel basic materials (Ni, Fe, Cr) were observed on the EDM-ed surface. The Inconel surface hardness increased by 251% when machined with a PM-Al-5Cu-1.5CNT electrode, while the PM-Al-5Cu-0.5CNT electrode achieved the highest surface finish. By using PM-processed electrodes, the elemental composition of the Inconel surface can be modified, improving both its hardness and surface finish to meet specific requirements.