Effect of Zn Content and SPS Process Parameters on the Microstructure and Hardness of Mg-Zn Alloys

This research investigated the microstructure and hardness of binary Mg-xZn (x=1, 3, 5) alloys produced by the spark plasma sintering process at different temperatures, times, and pressures. Taguchi quality function was used to model the process and obtain the optimal input parameters. Optical and scanning electron microscopes were used to analyze the microstructure and grain size of the alloys. Microstructural analyses revealed that the grain sizes directly increased by the Zn content. Meanwhile, the intermetallic phase of MgZn was formed in the alloys containing 3 and 5 wt. % Zn. Density and hardness measurements were employed for all alloys. The results also indicated that the highest hardness value was 92.5 HV for the alloy containing 1 wt. % Zn, while the highest relative density, 1.21, referred to the alloy containing 5 wt. % Zn, when the temperature, time, and applied pressure had the minimum values. Furthermore, by increasing temperature and pressure, the porosities were reduced. The grain size initially dropped and then ascended by merging the grains to form larger ones due to the enhanced diffusion kinetics.