Influence Factors and Microstructures of Machined Surface in Electrical Discharge Machining for SiC_w/2024 Aluminium Matrix Composite

摘要

The microstructures of machined surface of the specimens in electrical discharge machining (EDM) for SiC_w/2024 aluminium matrix composites were measured with scanning electron microscope (SEM) and Talysurf-6 roughometer, and the energy spectrums of them were analyzed using EDAX spectrometer. The results show that the microstructures of machined surface are the "birds nest" shape complex structures, and mainly by the formation of pits, flange convexes, bonding of aluminium droplets again, cracks and SiC_w whisker breakages. Moreover, deformation and failure modes of SiC_w whiskers have three kinds of fusing and breaking off, pulling out directly, bonding again. With the increase of pulse width, processing speed and roughness values of the machined surface will increase, too. However, with the increase of pulse interval, processing speed will rapidly decrease, but roughness values of machined surface will maintain the stability.