Effects of Zinc Concentration and Initial Condition on Precipitation Kinetics of Magnesium Alloys

Sammanfattning

Magnesium alloys are promising candidates for biomedical implants due to their ability to dissolve in the human body, which improves the surgical procedures making a secondary surgery to remove the implant unnecessary. However, one of the main challenges magnesium alloys faces in terms of an implant is their inferior strength compared to such permanent implant materials as stainless steel and titanium. In this work, Mg-Zn based alloys of high, medium and low zinc quantities and different processing states, homogenized and extruded, were heat treated to find peak aging time, which optimizes materials strength. During aging, the specimens were periodically extracted, and hardness tested to follow the process kinetics. It has been found that both the quantity of Zn in the Mg alloys, and processing state have significant impact on both aging kinetics and maximum hardness level at peak aging.Furthermore, the specimen microstructure was studied with SEM to analyze grain sizes and intermetallic particle structure. Grain sizes were determined by linear intercept method. Homogenized material showed bigger grain size and lower quantities of particles compared to the extruded samples.