Journal of Magnesium and Alloys (Jun 2020)
Mechanical and corrosion behaviour of hydroxyapatite reinforced Mg-Sn alloy composite by squeeze casting for biomedical applications
Abstract
Magnesium alloys have gained increasing attention for biomedical applications due to their biocompatibility and the biodegradability. Hydroxyapatite (HA) is known to be a highly bioactive because of its similar chemical and crystallographic structures to bone. Therefore, HA is believed to be a potential ceramic material for the fabrication of Mg based composites, to combine the advantages of both Mg and HA. But, in general, the composites known to be more susceptible to corrosion attack than the matrix alloy. Hence, in the present work, Sn is used as an alloying element to evaluate its effect on mechanical as well as corrosion properties of Mg/HA composites. Mg with 5 wt% HA and Mg-1 wt% Sn-5 wt% HA composites were prepared separately by stir assisted squeeze casting route. The phase analysis and microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS) respectively. Mechanical properties were evaluated by conducting the compression and micro hardness tests. Corrosion properties of as-cast composites were studied by linear polarization, Tafel and electrochemical impedance spectroscopy (EIS) techniques. The results of both XRD and SEM-EDS revealed that the main constitutional phases of as-cast Mg/HA composites were α-Mg and HA whereas, in Mg-Sn/HA composites, the phase Mg2Sn was observed along with fine distribution of HA particles. In both the cases, no interfacial reactions observed. The yield strength, ultimate compression strength and hardness were found to be increased with the addition of Sn in Mg/HA composites. Furthermore, the addition of Sn also played an important role in increasing the corrosion resistance of the Mg/HA composites which was attributed the refinement of grain size and the formation of Mg2Sn phase along the grain boundaries. Hence, it was concluded that the addition of Sn improves both mechanical and corrosion properties of Mg/HA composites.
