Berlin 2015 – wissenschaftliches Programm
MM 28.30: Poster
Dienstag, 17. März 2015, 18:30–20:30, Poster E
Effect of Mg addition on the mechanical properties of a Zn-Al-Cu alloy — •Zhicheng Wu, Liang Wu, Weiping Hu, Günter Gottstein, and Sandra Korte-Kerzel — Institut für Metallkunde und Metallphysik, RWTH Aachen, Kopernikusstr. 14, D-52074 Aachen, GERMANY
Zinc alloys are liable to creep even at only moderately elevated temperatures due to their low melting point of around 380∘C. In order to increase the strength and especially the creep resistance of a Zn-Al-Cu alloy by solid solution and precipitation strengthening, the effect of Mg addition was studied. On the basis of the composition of the commercial alloy Z410 (4wt% Al, 0.5wt% Cu), three laboratory alloys were produced with different amounts of Mg (0.04wt%, 0.2wt% and 0.3wt%) and characterized in terms of their mechanical properties and microstructure using tensile tests in conjunction with scanning and transmission electron microscopy. Tensile tests were performed at RT, 55∘C and 85∘C and strain rates of 5×10−4, 5×10−5 and 6×10−6/s−1. The true stress - true stain curves revealed at low strain rates (5×10−5 and 6×10−6/s−1) a regime with a nearly constant work softening rate. Based on the low strain rate tests, the steady state creep rate of the investigated Zn alloys was approximated in order to estimate the creep activation energy and stress exponent of the studied Zn alloys. It was found that the Zn alloy with medium Mg content (0.2wt%) had the highest yield strength both at RT and elevated temperatures and also the highest activation energy for creep. The underlying physical mechanisms of the observed phenomena will be briefly discussed.