Effect of Cu Content on Microstructure and Properties of Al-2.5Mg-xCu-0.2Si Alloy

Effect of Cu content on microstructure and properties of Al-2.5Mg-xCu-0.2Si alloys was investigated in this research. Results show that the microhardness of the alloy with Cu addition has an obvious rapid hardening effect due to the clustering of Cu and Mg at the early stage of aging. With further aging, the microhardness of the alloy increases again and reaches an obvious second peak due to the formation of S' phase and Guinier-Preston-Bagaryasky (GPB) zone. The increasing amount of Cu content results in a significant increase in tensile strength and yield strength while a reduction of elongation and intergranular corrosion performance. With the increase of Cu content, the intergranular corrosion performance of the alloy becomes worse. The alloy has a reasonably well corrosion performance when the Cu content is less than 1.14wt%. However, there is a significant reduction when the alloy contains 2.10wt% Cu. Based on these results, the alloy containing 1.14wt% Cu has better mechanical properties and corrosion resistance. Copyright © 2021, Northwest Institute for Nonferrous Metal Research. Published by Science Press. All rights reserved.