The effect of hydroxyapatite reinforcement and preparation methods on the structure and mechanical properties of Mg-HA composites

Magnesium composites with suitable reinforcement such as hydroxyapatite (HA) or tricalcium phosphate can offer improved mechanical and also biological properties, which points to them as possible candidates in medicine as biodegradable materials. The present paper deals with structure and mechanical properties of Mg-xHA (x=0, 2, 5, 10 wt.%) composites prepared from coarse Mg powder and nanoparticles of HA. Different preparation methods (milling, stamping, extrusion, spark plasma sintering) and process temperatures are combined to avoid the creation of agglomerates in structure and to reach improved mechanical properties. Hardness, compressive and three-point bending tests are performed for material characterization. On the basis of these results, authors confirm the clear effect of the volume fraction of reinforcement in composite on final properties, but authors also show even stronger effect of the preparation method on the mechanical properties of Mg-HA composites. Measured properties of selected final products, which reached about 500 MPa in ultimate compressive strength and flexural strength, slightly exceed values reported in literature and fulfil general requirements on mechanical properties for applications in medicine such as bone fixations.