Microstructure and mechanical properties of Mg-6Zn-xCu-0.6Zr (wt.%) alloys

The microstructures and mechanical properties of the new quaternary Mg-6Zn-xCu-0.6Zr alloys (x = 0, 0.5, 1.0 and 2.0 wt.%) have been investigated. The results show that the Cu content has a significant effect on the age-hardening response, tensile performance and fracture behavior of the alloys. The addition of 0.5 wt.% Cu resulted in a remarkable age-hardening response and a striking improvement of the room temperature tensile properties after an isothermal ageing at 180 degrees C. However, an excessive Cu addition of 2.0 wt.% caused the formation of continuous brittle grain-boundary intermetallic particles, thus degrading the age-hardening response and the mechanical properties of the alloy. The microstructural factors associated with the improvements in the mechanical properties are discussed in detail. (c) 2010 Elsevier B.V. All rights reserved.