Effects of plasma surface modification of Mg-2Y-2Zn-1Mn for biomedical applications

Magnesium (Mg) alloys have emerged as promising materials for biodegradable implants in orthopedic, oral, and cardiovascular applications. Despite their potential, high corrosion rate, and release of diatomic hydrogen in the surrounding environment remain the unmet challenges. In this research, oxygen plasma ion immersion implantation (O-PIII) was investigated in an attempt to modify the degradation rate of Mg-2Y-2Zn-1Mn alloy. In particular, the effects of pulse duration (t_pd) and pressure (p) on the degradation rate were investigated. For all the investigated conditions, plasma treatment enriched the surface chemical composition with O, forming a Mg- and Y- rich oxide layer. Mg and Y elements were mainly concentrated at grain boundaries. The concurrent phenomena of sputtering and energetic implantation led to crystalline Y₂O₃ formation. Electrochemical investigations confirm that the degradation rate of samples decreased significantly, from ∼0.23 mm/y for untreated to ∼0.07 mm/y for O-PIII conditions. These findings demonstrate the effectiveness of O-PIII in changing surface properties and controlling corrosion rate of Mg alloys.