Study on microstructure and dynamic corrosion behavior of degradable Mg-Y-Zn-Zr alloy with different Sr contents

Microstructure and corrosion behaviors of cast Mg-2Y-1Zn-0.4Zr-xSr alloys were investigated by using OM, SEM, immersion and electrochemical tests. The results show that the addition of Sr refines the grain, the grain size of Mg-2Y-1Zn-0.4Zr-0.3Sr alloy is the thinnest. the addition of Sr also changes the morphology and distribution of the second phase. The precipitation of W-phase at grain boundary decreases, while the precipitation of punctate W-phase and Mg0.97Zn0.03 phase in the grain increased. In addition, both immersion and electrochemical tests illustrates Mg-2Y-1Zn-0.4Zr-0.3Sr alloy has the best corrosion performance among the four investigated alloys, and shows a relatively uniform corrosion morphology on the surface. Moreover, as the Sr content increases, the corrosion mode of the alloy changes from intergranular corrosion to intragranular corrosion.