Effects of Minor Sr Addition on Biocorrosion and Stress Corrosion Cracking of As-Cast Mg-4Zn Alloys

Microstructure, biocorrosion, and stress corrosion cracking (SCC) behavior of as-cast Mg-4Zn-xSr alloys (x ≤ 0.4, in mass%) are studied by scanning electron microscopy, immersion testing, slow strain rate tensile testing, etc. A minor Sr addition (≤0.2%) in Mg-4Zn alloy can reduce the average corrosion rate and the corrosion current density in Hank’s solution, resulting from grain refinement, dispersion of the smaller secondary phase particles, and the more-protective corrosion product film. Thus, a minor Sr addition (≤0.2%) can improve both strength and plasticity of the Mg-4Zn alloy without increasing the SCC susceptibility, and the Mg-4Zn-0.1Sr alloy exhibits the best comprehensive properties.