A review on magnesium alloys for application of degradable fracturing tools

The vulnerable corrosion resistance of Mg alloys is regarded as one of the main disadvantages restricting their application, while it can be used as an extraordinary specialty in some particular fields, such as petroleum exploitation and medicine. In recent years, many Mg alloys with high corrosion rate and high strength have been developed for fracturing temporary plugging tools in the oil exploitation. This review briefly introduces the performance requirements of the degradable fracturing tools classified into mechanical and corrosion properties. Recent progress on corrosion behavior of degradable Mg-Al, Mg-Zn, Mg-RE alloys and Mg matrix composites is then summarized and discussed. Finally, the factors influencing the degradation rate of Mg alloys are analyzed and divided into secondary phase, texture, dislocation, grain size and surface film. From the summary, it can be found that addition of Ni or Cu to the degradable Mg alloys is a common and effective method to enhance the degradation rate due to increasing the amount of secondary phases and deteriorating the corrosion product layers. For the as-extruded degradable Mg alloys, grain size, texture and dislocation are the key factors affecting the corrosion rate under different processing conditions. We expect this review is helpful for those who are working on developing Mg-based functional materials with superior degradation rate.