Corrosion and corrosion-fatigue behavior of magnesium metal matrix composites for bio-implant applications: A review

Recently, the topic of bioresorbable metals, with much focus on magnesium for bone implant applications, has been an area of considerable investigation. Indeed, it could be argued that magnesium is the most promising biodegradable material currently being studied for use as an orthopedic skeletal fixation and joint replacement hardware. However, the fast degradation rate of magnesium-based materials in the physiological environment negatively affects their mechanical integrity and hence limits their biomedical use. The most critical conditions may occur when the implant is subjected to a corrosive physiological environment and a fluctuating load during daily activities. Hence, numerous studies have been published on the synthesis, alloying, and coating of magnesium to control degradation rate and increase strength and durability. Among the materials and strategies employed to achieve these goals, magnesium-based biocomposites have exhibited superior mechanical properties and acceptable biocompatibility. However, there is a lack of understanding of their corrosion and corrosion-fatigue behavior. Such understanding is necessary to qualify these new materials for various bio-implant applications. To this end, this paper reviews the recent advances in the corrosion and corrosion-fatigue behavior of magnesium-based biocomposites. It also provides a comprehensive discussion of different factors that influence the biocompatibility, corrosion, fatigue, and corrosion-fatigue of magnesium-based biocomposites as potential implant materials. This study emphasizes that despite the abundance of various studies on the corrosion behavior of magnesium-based biocomposites, there is an imperative need for more fatigue and corrosion-fatigue studies.