Investigating microstructural and mechanical properties evolution in biomedical AZ31 magnesium alloy under different casting conditions

Magnesium alloy AZ31 is highly valued for aerospace components, medical implants, and prosthetics due to its exceptional mechanical properties. Its density and elastic modulus closely match those of cortical bone, making it a promising material for orthopaedic applications. Its biodegradability further enhances its potential by eliminating the need for secondary surgeries. However, casting magnesium alloy AZ31 poses challenges due to its high reactivity, leading to oxidation, porosity, and phase segregation, which affect mechanical properties and surface integrity. This study focuses on a method for developing a customized, patient-specific AZ31 magnesium alloy implant using casting as the manufacturing technique. The microstructure and mechanical properties of AZ31 are investigated with respect to different casting parameters, pouring temperatures, shielding techniques, and furnace types. SEM and EDS identified primary α-Mg and secondary β-Mg17Al12 phases, as well as increased oxide layer thickness and phase segregation. XRF and XRD were used to confirm shifts in alloy composition and the presence of phases such as MgO and Al-Mn intermetallic, which have been shown to effect on mechanical properties. This study aims to develop an effective method for casting AZ31 magnesium alloy implants, giving significant insights to minimize oxidation while improving the mechanical properties and surface integrity of AZ31 alloy castings.