A study of long-term static load on degradation and mechanical integrity of Mg alloys-based biodegradable metals

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Vol. 219; pp. 45 - 54
• Main Authors: Koo, Youngmi, Jang, Yongseok, Yun, Yeoheung
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.05.2017; Elsevier BV
• Subjects: Biodegradability; Biodegradable materials; Biodegradable metals; Computed tomography; Crack propagation; Degradation; Four point bending; In vivo methods and tests; Integrity; Intergranular corrosion; Magnesium; Magnesium base alloys; Medical devices; Stress corrosion cracking; Stress corrosion cracking; Biodegradable metals; Magnesium; Four-point bending
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2017.02.009

•Long-term stress corrosion cracking (SCC) test of Mg alloys was performed.•AZ31B-H24 shows transgranular stress corrosion cracking (TGSCC) and ZE41A-T5 intergranular stress corrosion cracking (IGSCC).•Long-term static loading accelerated crack propagation, leading to the loss of mechanical strength. Predicting degradation behavior of biodegradable metals in vivo is crucial for the clinical success of medical devices. This paper reports on the effect of long-term static stress on degradation of magnesium alloys and further changes in mechanical integrity. AZ31B (H24) and ZE41A (T5) alloys were tested to evaluate stress corrosion cracking (SCC) in a physiological solution for 30days and 90days (ASTM G39 testing standard). Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) and micro-computed tomography (micro-CT) were used to characterize surface morphology and micro-structure of degraded alloys. The results show the different mechanisms of stress corrosion cracking for AZ31B (transgranular stress corrosion cracking, TGSCC) and ZE41A (intergranular stress corrosion cracking, IGSCC). AZ31B was more susceptible to stress corrosion cracking under a long term static load than ZE41A. In conclusion, we observed that long-term static loading accelerated crack propagation, leading to the loss of mechanical integrity.