Corrosion fatigue behaviors of two biomedical Mg alloys – AZ91D and WE43 – In simulated body fluid

• Published in: Acta biomaterialia Vol. 6; no. 12; pp. 4605 - 4613
• Main Authors: Gu, X.N., Zhou, W.R., Zheng, Y.F., Cheng, Y., Wei, S.C., Zhong, S.P., Xi, T.F., Chen, L.J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2010
• Subjects: Alloys - chemistry; Biocompatible Materials - chemistry; Biomedical metallic materials; Body Fluids - chemistry; Corrosion; Corrosion fatigue; Electrolytes - chemistry; Fatigue; Magnesium - chemistry; Magnesium alloy; Microscopy, Electron, Scanning; Stress, Mechanical; Surface Properties; Temperature; X-Ray Diffraction; Fatigue; Corrosion fatigue; Biomedical metallic materials; Magnesium alloy
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2010.07.026

Magnesium alloys have been recently developed as biodegradable implant materials, yet there has been no study concerning their corrosion fatigue properties under cyclic loading. In this study the die-cast AZ91D (A for aluminum 9%, Z for zinc 1% and D for a fourth phase) and extruded WE43 (W for yttrium 4%, E for rare earth mischmetal 3%) alloys were chosen to evaluate their fatigue and corrosion fatigue behaviors in simulated body fluid (SBF). The die-cast AZ91D alloy indicated a fatigue limit of 50 MPa at 10 7 cycles in air compared to 20 MPa at 10 6 cycles tested in SBF at 37 °C. A fatigue limit of 110 MPa at 10 7 cycles in air was observed for extruded WE43 alloy compared to 40 MPa at 10 7 cycles tested in SBF at 37 °C. The fatigue cracks initiated from the micropores when tested in air and from corrosion pits when tested in SBF, respectively. The overload zone of the extruded WE43 alloy exhibited a ductile fracture mode with deep dimples, in comparison to a brittle fracture mode for the die-cast AZ91D. The corrosion rate of the two experimental alloys increased under cyclic loading compared to that in the static immersion test.