Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 57 9 2025 11 22 Reinforcement of Magnesium-Matrix Biocomposites with Hydroxyapatite during Severe Plastic Deformation Reinforcement of Magnesium-Matrix Biocomposites with Hydroxyapatite during Severe Plastic Deformation 1127 1142 5992 10.22060/mej.2026.24785.7900 FA Seyed Ashkan Ghoreishizade Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran Hadi Allaei Oregani Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran Mohammad Sedighi Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran 0000-0001-6828-1732 Journal Article 2025 09 24 Metal biocomposites have garnered significant attention due to their combined benefits from both the matrix and reinforcement phases. Among these, magnesium-based biocomposites have been particularly emphasized in medical applications such as orthopedics and cardiovascular implants owing to their biocompatibility, biodegradability. However, the inferior mechanical properties of these composites have necessitated modifications to enhance their strength. Equal-Channel Angular Pressing (ECAP) is one of the Severe Plastic Deformation (SPD) techniques that contributes to grain refinement and the improvement of mechanical properties. Accordingly, this research investigates the effect of ECAP on the mechanical properties and microstructure of a magnesium/2.5 wt.% hydroxyapatite biocomposite. The samples were initially fabricated via mechanical magnetic stir casting followed by two passes of hot extrusion. They were then subjected to ECAP processing at 325°C using route BC with a channel angle of φ = 90°. The results indicate that increasing the number of ECAP passes leads to grain refinement and the formation of nanostructured grains. Moreover, a 33% improvement in mechanical strength compared to pure magnesium and a 15% enhancement compared to the twice-extruded magnesium/hydroxyapatite biocomposite were observed. Microhardness tests also revealed a 50% increase compared to pure magnesium and a 25% increase compared to the twice-extruded magnesium/hydroxyapatite biocomposite. Metal biocomposites have garnered significant attention due to their combined benefits from both the matrix and reinforcement phases. Among these, magnesium-based biocomposites have been particularly emphasized in medical applications such as orthopedics and cardiovascular implants owing to their biocompatibility, biodegradability. However, the inferior mechanical properties of these composites have necessitated modifications to enhance their strength. Equal-Channel Angular Pressing (ECAP) is one of the Severe Plastic Deformation (SPD) techniques that contributes to grain refinement and the improvement of mechanical properties. Accordingly, this research investigates the effect of ECAP on the mechanical properties and microstructure of a magnesium/2.5 wt.% hydroxyapatite biocomposite. The samples were initially fabricated via mechanical magnetic stir casting followed by two passes of hot extrusion. They were then subjected to ECAP processing at 325°C using route BC with a channel angle of φ = 90°. The results indicate that increasing the number of ECAP passes leads to grain refinement and the formation of nanostructured grains. Moreover, a 33% improvement in mechanical strength compared to pure magnesium and a 15% enhancement compared to the twice-extruded magnesium/hydroxyapatite biocomposite were observed. Microhardness tests also revealed a 50% increase compared to pure magnesium and a 25% increase compared to the twice-extruded magnesium/hydroxyapatite biocomposite. https://mej.aut.ac.ir/article_5992_675f9820626f5bc0afb47b57890b466e.pdf