Wear Behaviour of Aged Al-Cu-Mg Alloys Sliding Against C45 Steel and SiC Abrasive Paper

Abstract The present study reports dry sliding wear characteristics for cast, homogenized, solution treated, and aged Al-Cu-Mg alloys with four different compositions and different microstructures, aged under same conditions, sliding against C45 steel and a water proof SiC abrasive paper. Al-Cu-Mg alloys, a family of important aluminum alloys, are strengthened by the formation of fine (sub-micron) metastable precipitates. However, their wear characteristics are influenced not only by this precipitation induced hardness, but also by the presence of hard intermetallic particles (constituents) formed during solidification. A series of Al-Cu-Mg alloys with different Cu and Mg contents (namely 8.5 Cu + 1.25 Mg; 7.8 Cu + 1.0 Mg; 7.0 Cu + 0.75 Mg; and 4.5 Cu + 0.0 Mg, in wt. %) were produced and aged under the same conditions. These alloys were solution treated at 520°C for 5 hours, quenched in water at room temperature, and aged at 200°C. A scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) was used to characterize the constituent particles in these samples following heat treatment. The wear behaviour of the aged samples with various contents of Cu and Mg was investigated under dry sliding conditions using a pin-on-disc sliding wear test. The peak age hardness was approximately the same for all alloys examined, although the alloys containing magnesium had slightly higher hardness and were more resistant to over-ageing. With increased alloy content, the wear resistance of samples sliding against C45 steel increased, while the wear resistance of alloys sliding against SiC abrasive paper decreased. For the case of the steel wear surface, the improved aluminium wear resistance coinsides with increased amounts (expected) of eutectic constituent with alloy content. For the case of the SiC abrasive paper, the loss in wear resistance is related to the loss (i.e. pull-out) of Al-Cu-Mg particles during the test.