Corrosion behavior of as-cast magnesium-4 % zinc alloys in simulated body fluid solution: the influence of minor calcium and manganese addition

Abstract

Biodegradable magnesium alloys have been extensively investigated for medical applications. In order to explore magnesiumg alloys with good degradable resistance, the effects of minor amounts of calcium and manganese elements on the corrosion behaviors of newly designed as-cast degradable Mg-4Zn-xMn-xCa alloys have been investigated systematically in this study. The microstructural evolution of various magnesium alloys are measured by optical microscopy, x-ray diffraction, and scanning electronic microscopy. The corrosion properties are studied through immersion tests and electrochemical measurements. The results show that the grains are refined and the distribution of the intermetallic Mg-4Zn-xMn-xCa alloys is rearranged by adding calcium and manganese elements. The lowest corrosion rate of 3.79 mm/y is achieved on the as-cast Mg-4Zn alloy with 0.2 wt.% calcium and 1 wt.% manganese addition. Besides, the corrosion potential (E-corr) shifted to -1.546 V-SCE with the addition of 0.2 wt.% calcium and 1 wt.% manganese. This is because the grain size refinement and the formation of Mg2Ca and Ca2Mg6Zn3 phases. The as-cast Mg-4Zn-1Mn-0.2Ca alloy can be considered an ideal material for biodegradable implant material application.