Electrical discharge machining of Al2024-65 vol% SiC composites

In the present work, the wire electrical discharge machining (WEDM) process of the 65 vol% SiCp/2024Al composite prepared by pressure infiltration methods has been investigated. The microstructure of the machined composite was characterized by scanning electron microscope, the average surface roughness (Ra), X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy (TEM) techniques. Three zones from the surface to the interior (melting zone, heat affected zone and un-affected zone) were found in the machined composites, while the face of SiC particles on the surface toward the outside was "cut" to be flat. Increase in Al and Si but decrease in C and O were observed in the core areas of the removed particles. Si phase, which was generated due to the decomposition of SiC, was detected after the WEDM process. The irregular and spherical particles were further observed by TEM. Based on the microstructure observation, it is suggested that the machining mechanism of 65 vol% SiCp/2024Al composite was the combination of the melting of Al matrix and the decomposition of SiC particles.