Influence of Cu and Mg addition on age-related deterioration in strength and creep behavior of Zn-12Al die casting alloys

The influence of the chemical composition of Zn-12Al- Cu- Mg ( = 1, 5; = 0.05–1.4 mass%) die casting alloys on age-related deterioration in mechanical strength and creep behavior was investigated. Tensile tests were performed after aging at room temperature for 1 day and at 100 °C for 1 week. Creep tests were carried out under tensile stresses of 25, 50 and 100 MPa at 100, 130 and 160 °C. Cu addition suppressed age-related deterioration of proof stress by suppressing the coarsening of the eutectic structure during the aging. Creep resistance was improved by the Mg addition, whereas the Cu addition has a deleterious effect on creep resistance. The results show that the age-related deterioration of Zn-12Al alloys can be improved without sacrificing creep resistance by the complex addition of Cu and Mg.