Mechanical and Corrosion Performance of Hot-Pressed Magnesium Composites

Magnesium-based materials are promising candidates for biodegradable implants due to their biocompatibility and density close to natural bone. However, their rapid corrosion rate and relatively low mechanical strength limit their clinical application. To overcome these challenges, Sn was added to promote the formation of strengthening Mg2Sn intermetallic phases, Ca was incorporated to enhance grain refinement and biocompatibility, and Y2O3 nanoparticles were introduced to improve hardness and corrosion resistance. In addition, powder metallurgy followed by hot pressing was employed to achieve enhanced densification and microstructural homogeneity. This study investigates the effects of Sn, Ca, and Y2O3 additions on the microstructure, mechanical, tribological, and corrosion properties of magnesium based composites. Four compositions were fabricated: pure Mg, Mg-15 wt.% Sn, Mg-15Sn-5Ca, and Mg-15Sn-5Ca-1Y2O3. XRD and SEM analyses confirmed the formation of Mg2Sn intermetallics, successful incorporation of Y2O3 particles, and significant microstructural refinement. The addition of Sn and Ca reduced porosity from approximately 10% in Mg-15Sn to about 5% in Mg-15Sn-5Ca and improved densification. Hardness increased from 47.7 HV for pure Mg to 68.5 HV for Mg-15Sn-5Ca and further to 74.9 HV for Mg-15Sn-5Ca-1Y2O3. The compressive strength improved from 97 MPa for pure Mg to 203 MPa for Mg-15Sn-5Ca, while the Y2O3-containing composite maintained a high strength of 187 MPa. The wear rate decreased from 0.117 g/min for pure Mg to 0.0122 g/min for Mg-15Sn-5Ca, with an increase to 0.0255 g/min after Y2O3 addition. Electrochemical measurements in simulated saliva fluid showed that the corrosion rate increased from 1.004 mm/year for pure Mg to 2.11 mm/year for Mg-15Sn and 2.06 mm/year for Mg-15Sn-5Ca. Following the incorporation of 1 wt.% Y2O3, the corrosion rate decreased to 0.96 mm/year, representing a reduction of approximately 53.4% relative to Mg-15Sn-5Ca and approximately 4.4% relative to pure Mg.