Influence of Ag on microstructure, mechanical properties and tribological properties of as-cast Al-33Zn-2Cu high-zinc aluminum alloy

The effect of Ag on the microstructure, mechanical properties, and tribological properties of Al-33Zn-2Cu alloys was investigated. The results show that the mechanical properties of the high-zinc aluminum alloy increase linearly with increasing silver content. The yield strength, tensile strength and elongation of the Al-33Zn-2Cu-0.6Ag alloy are 370 MPa, 433 MPa and 8.2% respectively. Wear resistance was also significantly improved. As the silver content in the Al-33Zn-2Cu alloy increases, the density of the η' phase in the α matrix increases. The addition of Ag aggravates the discontinuous precipitation of the α + η phase, resulting in the inhibition of the continuous large α + η phase in the alloy and the transformation into small discontinuous precipitation phases. Besides, as the Ag content increases, the lamellar α + η phases formed at the grain boundaries become finer and denser. This study may provide innovative ideas for alloy design of high-zinc aluminum alloys.