Processing of Metal Matrix AA2124 Aluminium Alloy Composites Reinforced by Alumina and Silicon Carbide by Powder Metallurgy Techniques

摘要

This work aims the processing of metal matrix AA2124 aluminium alloy composites reinforced by alumina (Al_2O_3) and silicon carbide (SiC). The composites were manufactured by powder metallurgy techniques, in a grinding using a ball mill spex type (high energy) at a ratio of balls/ powders of 10:1 and grinding time of 30 and 60 minutes using stearic acid (C_(18)H_(36)O_2) as lubricant to each one of the samples. The fractions used in both reinforcements were 5, 10 and 15% in mass. The microstructural characterizations of AA2124 alloy powders with the reinforcements of alumina (Al_2O_3) and silicon carbide (SiC) powders were obtained by scanning electron microscopy (SEM) and the particles sizes and distribuition of the particle sizes in powders produced were obtained by laser diffraction, whereas the sintered characterizations were obtained by scanning electron microscopy (SEM) and mechanical characterization of the sintered tests was achieved by Vickers hardness (HV). The composites were uniaxially cold compacted (room temperature), at a pressure of 7.01 / cm~2, thus forming small pellets that were sintered (at a temperature of 500 ℃) in a vacuum furnace at IPEN (SP). There was observed the influence of the respective bulk fractions of reinforcement particles used in mechanical characteristics presented in the resulting composites.