The microstructure, tensile properties, and creep behavior of Mg-Zn alloys containing 0-4.4 wt.% Zn

This paper describes the microstructure, tensile, and tensile-creep behavior of a series of Mg-Zn alloys ranging from 0 to 4.4 wt.% Zn. The microstructures consisted of equiaxed hexagonal-close-packed grains with fine precipitates preferentially located at grain boundaries. Some of the microstructures contained fine laths within the equiaxed grains. The finest grain sizes were observed for a Zn composition of 4 wt.%. Tensile experiments were performed at room temperature and 150 °C while creep experiments were conducted at 150 °C for applied stresses between 30 and 50 MPa. The greatest tensile and creep resistance was exhibited by Mg-4.1Zn which contained 0.2 wt.% Y. The measured creep exponent for the Mg-4.1Zn alloy was 4.2, suggesting dislocation climb as the dominant creep mechanism. Overall, Zn proved to be a potent grain refiner and strengthener for Mg where 4 wt.% appeared to be the optimal Zn content for tensile and creep strengthening over the range of alloying additions examined.