An assessment on modified AZ80 alloys for prospect biodegradable CV stent applications

In medicine, stents are inserted into an artery to prevent local constrictions to blood flow. Commonly used stents are permanent metal stents, yet developments in this area are more and more heading towards biodegradable stents. Implants made of materials that can dissolve in the patient's body by being biodegradable, negates the necessity of implant removal, or long term complications of carrying substances unknown to body. Magnesium alloys are frequently addressed in the literature concerning biodegradable implant applications [1-3], mainly concerned with the in vitro and/or in vivo material degradation. There has been ongoing research on improving corrosion properties of magnesium alloys [4] and linking the corrosion resistance to the thermomechanical history of magnesium alloys [5-6]. The objective of this study is to investigate the consequences of thermomechanical treatments on not only corrosion resistance but also on the mechanical performance, which generally counteract with each other. Cast magnesium alloys have superior corrosion resistance compared to wrought alloys yet exhibit very poor ductility [7]. To this purpose, utilizing a commercial grade AZ80 alloy and an experimental AE70 alloy, several heat treatments are applied and the resulting corrosion resistance and mechanical performance is tested. It is seen that, the rare-earth modified alloy AE70 shows improved corrosion resistance by annealing without severe grain growth, yet at the expense of strength and ductility.