EFFECT OF VOLUME FRACTION OF REINFORCEMENT AND MILLING TIME ON PHYSICAL AND MECHANICAL PROPERTIES OF AI7075-SiC COMPOSITES FABRICATED BY POWDER METALLURGY METHOD

摘要

The volume fraction of reinforcement and milling time are two important factors in fabricating aluminum metal matrix composites via powder metallurgy (P/M) techniques. In the present work, the effects of volume fraction of reinforcement and milling time on the micro-structure, relative density, hardness, and compressive strength were studied. The AI7075 and SiC powders were mixed by a planetaiy ball mill for about 4 and 8 h, and AI7075-x vol.% SiC specimens (x - 4, 6, 8) were fabricated by a uniaxial cold press and sintered at 873 K (600 °C) for 1 h. The crystallite size and morphology of the powder particles were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results showed that with increasing milling time and volume fraction of the reinforcement phase, the hardness and compressive strength increased. The SEM illustrates that the number of voids increases as SiC content increases, but their size decreases.