Advances toward stress-assisted degradation of biomedical Mg alloys
Biomedical Mg alloys are candidate biodegradable metals for orthopedic and cardiovascular implants, yet their in vivo service life is governed by coupled mechanical-chemical attack that accelerates loss of mechanical integrity. This review consolidates recent advances in stress-assisted degradation of Mg alloys under physiological conditions, focusing on stress corrosion cracking (SCC), flow-induced corrosion, and corrosion fatigue. Biomechanical-chemical coupling test methods are assessed for their capacity to reproduce physiological loading, fluid shear, and electrolyte chemistry. Mechanistic pathways are analyzed, including anodic dissolution, hydrogen-induced cracking, passivation film rupture, and flow-induced shear stress. Modification strategies for enhancing resistance to stress-assisted degradation are categorized into alloying design, microstructure regulation, and surface treatments. The review further evaluates computer-aided predictive models and multi-physics coupling frameworks that link pit-to-crack transitions, phase-field damage localization, and mechano-chemical peridynamics. Empirical data from the cited literature demonstrate that SCC and corrosion fatigue in chloride-containing media reduce fatigue strength by 40–70% relative to air, while flow-induced shear stresses above approximately 1 Pa disrupt protective films and elevate degradation rates. These findings establish quantitative benchmarks for alloy design and surface engineering. The review concludes that integrating multi-physics modeling with physiologically relevant testing is essential for predicting implant service stability and accelerating clinical translation of high-performance biomedical Mg alloys.