Effect of glucose on corrosion fatigue behavior and crack propagation mechanism of Mg-xGa alloys in simulated body fluid

Purpose – This paper aims to investigate the fatigue crack propagation mechanisms of extruded Mg–xGa alloys in air and glucose-containing corrosion environments, focusing on the roles of microstructural evolution and glucose-induced Ca-P passivation. Design/methodology/approach – Fatigue crack propagation behavior of extruded Mg–xGa (1.0–2.0 wt%) alloys was investigated under cyclic loading in air and glucose-containing corrosion media. Crack-tip deformation behavior was examined using optical microscopy (OM) and scanning electron microscopy (SEM). Surface corrosion films and glucose-induced Ca–P passivation layers formed in corrosion media were characterized by SEM and X-ray photoelectron spectroscopy (XPS). Findings – Fatigue crack propagation in Mg–xGa alloys were mainly governed by grain refinement and extensive twinning at the crack tip, which increase local strength and reduce cyclic strain amplitude. These microstructural features do not deteriorate crack growth resistance. Interestingly, in corrosion environments, higher glucose concentration promotes the formation of a dense Ca–P layer that provides effective crack-tip passivation. This passivation suppresses the ratcheting effect, slows crack propagation and even improves corrosion fatigue life, indicating that Ca–P layer formation was the dominant factor controlling fatigue crack propagation (FCP) resistance. Research limitations/implications – This study is limited to extruded Mg–xGa alloys and specific glucose concentrations, which may not fully represent the complexity of in-vivo biochemical environments. The corrosion fatigue behavior was evaluated under controlled laboratory conditions and long-term physiological interactions, protein adsorption and dynamic biological responses were not included. Despite these limitations, the findings provide important insights into crack-tip passivation mechanisms and offer guidance for optimizing Mg-based implant alloys for improved corrosion fatigue performance. Practical implications – The findings provide practical guidance for designing Mg-based biodegradable implants with improved corrosion fatigue resistance. The demonstrated role of glucose-induced Ca-P passivation suggests that tailoring alloy composition and promoting controlled surface mineralization can effectively enhance crack-tip stability in physiological environments. These insights support the development of safer and longer-lasting Mg alloy implants, and offer a reference for optimizing material selection and surface treatments in biomedical engineering applications. Originality/value – The FCP behavior of Mg–xGa alloys in glucose-containing physiological corrosion environments was systematically investigated for the first time. These findings provide new mechanistic insights beyond current common understanding.