Structure and properties of Zn–Al–Cu alloy reinforced with alumina particles

Metal matrix composites were prepared using Zn–21Al–2Cu (zinalco) as base alloy, by means of powder metallurgy techniques. Alumina particles were used as reinforcement in concentrations of 7, 14 and 27% in volume. The composites prepared using this technique exhibit good consolidation even before sintering. Samples of the base alloy and of the different composites were sintered in air at 473 K in periods of 10, 20, 40 and 80 h. Measurements of density, hardness and yield strength in compression were performed in green and sintered materials. A decrease of 30% in density is achieved for the 27 vol.% alumina composite compared with the unreinforced base alloy. An improvement of 13% in the values of conventional yield strength and hardness is shown for the composite with 7 vol.% alumina deformed at a strain rate of 10−3 s−1 and after 20 h of sintering time. At higher strain rates, the ductility of unreinforced and composite materials is reduced for all alumina concentrations.