EFFECT OF VOLUME FRACTION OF REINFORCEMENT AND MILLING TIME ON PHYSICAL AND MECHANICAL PROPERTIES OF Al7075–SiC COMPOSITES FABRICATED BY POWDER METALLURGY METHOD

Abstract

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 microstructure, relative density, hardness, and compressive strength were studied. The Al7075 and SiC powders were mixed by a planetary ball mill for about 4 and 8 h, and Al7075–x vol.% SiC specimens (x = 4, 6, 8) were fabricated by a uniaxial cold press and sintered at 873 K (600 ºC) 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.