Friction and wear properties of cast aluminum alloy with high Cu content

Al-Cu alloy samples with 5%-20% (mass fraction) Cu were prepared by die-casting process. The hardness of the samples was measured on a Brinell hardness tester. The wear experiments with three kinds of load (1-5 N) were carried out with a ball-disk reciprocating wear tester. The wear mechanism of the samples with different Cu contents was analyzed by SEM and EDS. The results show that as the Cu content increases from 5% to 20%, the volume fraction of θ phase in Al-Cu alloy increases from 2.00% to 25.80%, and the size of θ phase increases gradually; the hardness increases from 59HB to 170HB. The coefficient of friction changes within the range of 0.4-0.85; with the increase of Cu content, the specific wear rate of Al-Cu alloy samples decreases sharply at first and then tends to be gentle. When Cu content is more than 15%, the specific wear rate of alloy samples does not change much, and the lowest specific wear rate is about 4.1×10-4 mm3·N-1·m-1. The specific wear rate of samples with lower Cu content changes significantly with the load, and the specific wear rate difference decreases with the increase of Cu content. The main wear mechanisms of Al-Cu alloys are adhesive wear and abrasive wear. For samples with low Cu content, adhesive wear is dominant; while for samples with high Cu content, abrasive wear is dominant. With the increase of load, the adhesive wear degree of the samples with low Cu content increases, and the abrasive wear degree of the samples with high Cu content increases.