Effect of powder metallurgy parameters on microstructure, mechanical, and bio-corrosion properties of Mg-alloys for biodegradable orthopedic implants

Magnesium-based alloys have attracted increasing attention for biomedical applications due to their biocompatibility, biodegradability, and mechanical properties used in biodegradable temporary medical devices. Processing of magnesium-based alloys strongly affects microstructure, mechanical performance, and bio-corrosion properties. This study investigates the influence of powder metallurgy processing parameters on the microstructure, mechanical properties, and bio-corrosion behavior of Mg-30Zn-5Ca-3Mn alloys aimed at orthopedic applications. Employing a full factorial design, parameters such as milling time, milling speed, heating rate, and heating time were systematically varied, and an L₁₆ orthogonal experimental design was conducted. Characterization techniques, including XRD, mechanical testing, and immersion testing, were used to analyze the developed alloys. The results demonstrated that processing conditions significantly affect the amorphous and crystalline phase content, which in turn impacts mechanical strength and biodegradability. The result of tensile strength, microhardness, and bio-corrosion rate range (360-553 MPa), (240-312.5 HV) and (0.13-0.23 mm/year) was revealed, respectively. The processed alloys with higher milling speeds, longer milling time, rapid heating rate, and shorter sintering times favored the formation of predominantly amorphous microstructure which further enhances mechanical strength (higher microhardness (312.5 HV) and tensile strength (553 MPa) and reduces biodegradation rate (0.13 mm/year) while those with shorter milling show promoted crystalline phases and lower mechanical properties and higher bio-corrosion rate. Milling time was the highest significant parameter. These findings provide critical insights into tailoring Mg-based biodegradable implants with desirable mechanical and corrosion properties for orthopedic use, and the bio-corrosion rate and mechanical properties of (Mg-30Zn-5Ca-3Mn) alloy can be tuned by varying the processing parameters.