Creep behaviour of eutectic Zn-Al-Cu-Mg alloys

In this study we investigated the creep behaviour of three eutectic ZnAl4Cu1Mg alloys with different Mg contents, namely ZnAl4Cu1Mg0.04, ZnAl4Cu1Mg0.21 and ZnAl4Cu1Mg0.31 (in wt%), using uniaxial tensile creep tests at temperatures between 25 °C and 105 °C. Furthermore, we studied the creep properties of the individual microstructural constituents of the ZnAl4Cu1Mg0.31 alloy using nanoindentation creep experiments at room temperature (25 °C) and 85 °C. Increasing Mg content causes an acceleration of the creep rate of ZnAl4Cu1 alloys. Zn-Al eutectic and eutectoid structures show a lower creep resistance than the η-Zn matrix phase. Stress exponents of 6.9-8.0 and creep activation energy values of 93-104 kJ/mol are obtained during the uniaxial tests, which suggests dislocation controlled creep.