The discharge gap phenomena in powder-mixed electrical discharge machining are examined using SiC powder mixing in water dielectric liquid. Surface modifications on machined work materials are investigated by means of optical, scanning electron microscopy and energy-dispersive spectroscopy. The experimental studies revealed that the surface morphology drastically affected the additives as means of secondary discharges and particle migration from dielectric liquid. Such mechanisms do not occur randomly and indicate a robust dependency with respect to powder suspension concentration, pulse on duration and current. The influence on discharge transitivity with respect to suspended particle concentration is noted with pock shape development due to secondary discharges followed by an intermediate stage signifying a sudden increase in particle migration from the dielectric liquid. The particles decomposed on the surface at specific operational conditions demonstrating the possibility of methodical surface alloying using the process. Finally, the mechanisms involved were elaborated with respect to operational parameters and discussed based on the experimental results.