Fabrication and Study of Wear Properties of AA8090 Composite Reinforced with SiC Particles after Precipitation Hardening with Directional Quenching

AA8090 is an extra light and deformable group of lithium containing aluminum alloys which have recently replaced some aerospace aluminum alloys, such as 2000 and 7000 series, due to their higher elastic modulus and lower specific weight. In this study, AA8090 matrix composites containing 3, 6 and 9 vol.% SiC were cast using a modified stir casting method. The casting billets were deformed though a hot extrusion operation, followed by a precipitation hardening treatment (T6) with directional quenching and aging at 190 °C. Wear tests were conducted before and after the precipitation hardening (at the peak hardness aging time) using the pin-on-disc method at loads of 10, 20 and 30 N. All samples exhibited a mild wear at 10 and 20 N wear loads, which turned into a sever wear at 30 N. It was shown that increasing the SiC content in the composite samples reduces the wear rate. Also, the wear results after precipitation hardening indicated a decrease in the wear rate only at the wear loads of 10 and 20 N. At the wear load of 30 N, the wear rate increased after precipitation hardening. This behavior was attributed to a transition in the wear mechanism from abrasive to adhesive by increasing the load.