The corrosion characteristic and mechanism of Mg-5Y-1.5Nd-xZn-0.5Zr(x=0,2,4,6 wt.%)alloys in marine atmospheric environment

The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectrometry and X-ray Diffraction.The exposure corrosion experiment of these magnesium alloys was tested in South China Sea and KEXUE vessel atmospheric environment.The corrosion characteristic and mechanism of magnesium alloys of Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were analyzed by weight loss rate,corrosion depth,corrosion products and corrosion morphologies.The electrochemical corrosion tests were also measured in the natural seawater.The comprehensive results showed that Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy existed the best corrosion resistance whether in the marine atmospheric environment and natural seawater environment.That depended on the microstructure,type and distribution of precipitated phases in Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy.Sufficient quantity anodic precipitated phases in the microstructure of Mg-5Y-1.5Nd-4Zn-0.5Zr alloy played the key role in the corrosion resistance.

In situ engineered magnesium alloy implant for preventing postsurgical tumor recurrence

Invasive tumors are difficult to be completely resected in clinical surgery due to the lack of clear resection margins,which greatly increases the risk of postoperative recurrence.However,chemotherapy and radiotherapy as the traditional means of postoperative adjuvant therapy,are limited in postoperative applications,such as multi-drug resistance and low sensitivity,etc.Therefore,an engineered magnesium alloy rod is designed as a postoperative implant to completely remove postoperative residual tumor tissue and inhibit tumor recurrence by gas and mild magnetic hyperthermia therapy(MMHT).As a reactive metal,magnesium alloy responds to the acidic tumor microenvironment by continuously generating hydrogen.The in-situ generation of hydrogen not only protects the surrounding normal tissue,but also enables the magnesium alloy to achieve MMHT under lowintensity alternating magnetic field(AMF).Furthermore,the numerous reactive oxygen species(ROS)produced by heat stress will combine with nitric oxide(NO)generated in situ,to produce more toxic reactive nitrogen species(RNS)storm.In summary,engineered magnesium alloy can completely remove residual tumor tissue and inhibit tumor recurrence by MMHT and RNS storm under low-intensity AMF,and the biodegradability of magnesium alloy makes great potential for clinical application.