Effect of Sr on the microstructure and biodegradable behavior of Mg–Zn–Ca-Mn alloys for implant application

Highlights: • The Mg_65.2-xZn₃₀Ca₄Mn_0.8Sr_x (x=0, 0.3, 0.5 and 0.8) amorphous matrix composites were prepared by copper mold casting • Introducing 0.3at% and 0.5at.% of Sr to Mg₆₆Zn₃₀Ca₄Mn_0.8 would improve glass forming ability and corrosion property. • The cellular-behavior evaluation demonstrated that Mg_64.7Zn₃₀Ca₄Mn_0.8Sr_0.5 alloy showed good vitro cytocompatibility. • A schematic diagram was proposed to illustrate the corrosion mechanism. In this paper, the effect of Sr on the microstructure and bio-corrosion behavior of Mg_65.2−xZn₃₀Ca₄Mn_0.8Sr_x (x = 0, 0.3, 0.5 and 0.8) amorphous matrix composite were investigated by X-ray diffraction, differential scanning calorimetry, scanning electron microscope, electrochemical measurements, immersion test and in vitro cytotoxicity test, respectively. Compared to the Mg–Zn–Ca-Mn alloy, the Sr-bearing alloys with minor Sr incorporation improved the glass formation ability and bio-corrosion resistance significantly. The corrosion products of the Mg_65.2−xZn₃₀Ca₄Mn_0.8Sr_x (x = 0, 0.3, 0.5 and 0.8) alloys mainly contained Zn(OH)₂, hydroxyapatite and phosphate after 124 h static immersion test, which were beneficial to the bone growth. The results suggested that the novel Mg_64.7Zn₃₀Ca₄Mn_0.8Sr_0.5 alloy possessed a good corrosion resistance and biocompatibility, showing a promising candidate for the biodegradable implants.