Corrosion morphology of biodegradable ZE21B Mg alloy microtubes under dynamic corrosion tests

In the corrosion tests, yttrium (Y) element reacts with oxygen (O) element to form Y-O compound, generating a protective corrosion layer to isolate magnesium (Mg) alloy from further attack of corrosion medium. To better illustrate the protective effects of Y-O compound on corrosion morphology of biodegradable Mg alloys stents, in vitro dynamic corrosion tests were conducted for ZE21B Mg alloy microtubes. Under dynamic flow, Mg-O layer and calcium-phosphate (Ca-P) layer peeled off from microtubes, and the compact and flat Y-O layer started to emerge, protecting ZE21B Mg alloy microtubes against flow induced corrosion.