Thermal stability, grain growth kinetics, mechanical properties, and bio-corrosion resistance of pure Mg, ZK30, and ZEK300 alloys: A comparative study

Abstract

Thermal stability, grain growth kinetics, tensile properties, and corrosion resistance of commercially pure (CP) magnesium can be tailored by zinc addition in conjunction with small additions of zirconium and rare earth (RE) elements, which need to be systematically investigated. Accordingly, the thermal stability, grain growth kinetics, tensile properties, and bio-corrosion resistance of hot rolled CP Mg, and ZK30 (Mg-3Zn-0.5Zr) and ZEK300 (Mg-3Zn-0.5RE-0.5Zr) alloys were compared in this work. The solute drag effect of Zn in the ZK30 alloy and the Zener pinning effect of CeZn 5 compound in the ZEK300 alloy were responsible for the improved thermal stability and higher grain growth activation energy of these alloys compared to CP Mg. The tensile properties of hot rolled ZK30 and ZEK300 alloys were superior due to their fine grain sizes. Moreover, corrosion tests in simulated body fluid (SBF) solution confirmed the higher corrosion resistance of the ZEK300 alloy for biomedical implant applications. The shear punch testing (SPT) results revealed that the ZEK300 alloy can better retain its superior mechanical properties during deformation/testing at elevated temperatures. Grain growth annealing led to a decrement in strength but an increment in the total elongations, and hence, the highest tensile toughness was obtained for the ZEK300 alloy with an average grain size of ~ 8.5 μm. Accordingly, this work proposed that RE addition at the micro-alloying level to a lean Mg-Zn alloy is quite effective in the enhancement of thermal stability, room/elevated-temperature mechanical properties, and bio-corrosion resistance.