The strain rate-dependent stress corrosion cracking behavior of a biodegradable Mg-Zn-Cu alloy

In this study, an as-extruded Mg-6Zn-0.5Cu alloy for potential biomedical applications with a focus on its tensile properties, electrochemical behavior and stress corrosion cracking (SCC) susceptibility via slow strain rate tensile in Hank’s solution at room temperature was investigated. The results demonstrated that the alloy exhibited a corrosion rate of 0.121 mm/y, yield strength of 149 MPa and elongation of 11.3%, which satisfied fundamental requirements for metallic implants. The SCC susceptibility index (ISCC) showed a distinct inverse dependence on strain rate, increasing from 17.5% at 5 × 10− 5 s− 1 to 48.7% at 5 × 10− 7 s− 1. The SCC behavior was governed by a synergistic interaction between anodic dissolution (AD) and hydrogen embrittlement (HE). Localized AD initiated microcracks at stress concentration sites, while absorbed hydrogen diffused to these regions and promoted crack propagation via HE. These findings underscore the promise of Mg-6Zn-0.5Cu alloy as a biodegradable orthopedic implant material and provide valuable insights for designing Mg alloys with optimized corrosion resistance and mechanical integrity.