Investigating the Degradation Behavior of Grain Refined WE43 Magnesium Alloy Produced by Friction Stir Processing for Medical Implant Applications

Abstract

Developing Magnesium (Mg) based degradable implants for orthopedic applications is an attractive research area for the past two decades in the biomedical engineering. Mg is well accepted by human system and does not cause any health abnormalities during its degradation in the physiological environment. However, in order to improve its life span by controlling the aggressive degradation, novel Mg alloys are developed and subjected to different treatments to enhance their performance to tailor as promising candidates for implant manufacturing. In this context, recently, a special attention is paid towards using rare earth containing Mg alloys due to their excellent mechanical and corrosion resistance properties. Hence, in the present work, WE43 Mg alloy has been selected and the microstructual modification was carried out by friction stir processing. The role of grain refinement on the degradation behavior of FSPed WE43 Mg alloy was assessed by immersing the samples in simulated body fluids. From the microstructural studies, grain size reduction from 46 ± 4.2 µm to 16.1 ± 5.4 µm was achieved after FSP. The larger intermetallic particles were also observed as dissolved into the solid solution grains and fewer intermetallic particles were remained in the stir zone of FSPed alloy. After immersion studies, the surface of the samples was deposited with mineral phases and were analyzed by X-ray diffraction analysis and scanning electron microscope and found that the grain refinement achieved by FSP has a significant effect on increasing the mineral depositions which helps to control the degradation rate of the samples.