Fabrication of Magnesium/Hydroxyapatite Bio-composite Using Stir Casting Method

Magnesium and its alloys are suitable and applicable materials for orthopedic implants. Indeed, they have perfect biocompatibility and their mechanical properties are similar to natural bone. Moreover, because of their biodegradable behavior, they do not need to be removed after complete healing, which could prevent further surgeries. However, the corrosion rate of magnesium is too much in body environment, which sometimes do not let bone to be healed sufficiently. Therefore, in order to control its corrosion rate and enhancing its mechanical properties, producing magnesium matrix composites is considered as a solution. In this work, magnesium/hydroxyapatite composite has been fabricated using stir casting method. Powders of hydroxyapatite, which is the major composition of natural bone, have been prepared from bovine bone. After casting the metal matrix composite (MMC), the as-cast billet was extruded with 20.63:1 extrusion ratio. Eventually, mechanical properties of the MMC have been studied containing tension, compression and Micro-hardness tests. In addition, the particle distribution has been investigated, using an optical microscopy. The results show that the Micro-hardness of magnesium matrix is remarkably increased by adding hydroxyapatite powder. Also, the yield stress is increased in both compression and tension tests by increasing the amount of reinforcement, while the maximum elongation reduced and ultimate stresses shows different behaviors.