Effect of strontium on microstructure, mechanical, and biological responses of Mg–Al–Zn–Sr alloys

In the present study, Mg alloys were prepared with different strontium contents and investigated for applications as resorbable implants (screws, plates, stents etc.). Microstructural characterisation and phase analysis were performed by optical microscopy, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. Alloy with 0.5 wt-% strontium results in a microstructure with fine grains (179 ± 22 µm) and the highest second phase precipitates (area-fraction ∼1.55%). The immersion and electrochemical measurements were performed at different times in Hanks’ solution. The corrosion rate decreased with increasing strontium amount owing to precipitate barrier and protective corrosion products. In vitrobiocompatibility test was carried out by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. The cell viability decreases with an increase in strontium content owing to presumably higher fraction of the Mg17Sr2phase.