Particle migration and surface modification on Ti6Al4V in SiC powder mixed electrical discharge machining

The study examines the impact of SiC powder concentration on surface topography, particles deposition and subsurface structures in powder mixed electrical discharge machining (PMEDM) of Ti-6Al-4V-ELI work material. It was observed that low pulse currents and high suspended particle concentration in dielectric liquid enhance the material transfer mechanism in particulate form. The subsurface properties of such surfaces exhibited a distinctive and harder re-solidified layer structure that indicates a unique material transfer mechanism takes place during machining. The particles placed close to a discharge column directed towards the melted metal pool due to the sudden closure of the plasma channel. When the main discharge channel subdivided into several secondary discharges, the suspended particles in dielectric liquid stuck among the scattered sub discharges and increased the probability of penetrating into the melted metal pool at the end of a discharge. Therefore, the formation of secondary discharges favoured the improved SiC transfer in particulate form. However, increasing the pulse current deplete the material transfer mechanism in particulate form due to the inadequacy of secondary discharges.