Microstructural Evolution and Mechanical Performance of Magnesium-Niobium Composites with Potential for Biomedical Applications

Abstract

This study used the powder metallurgy technique to fabricate biocompatible niobium (Nb)-reinforced pure Mg matrix composites. The impact of Nb particulate contents (2.5 wt.%, 5 wt.%, 7.5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) on the microstructure, density, mechanical properties and fracture behavior of the resulting composites was investigated. The results indicated a uniform distribution of Nb reinforcement particles with excellent interfacial bonding and minimal porosity. The addition of Nb slightly refined the grain structure. Mechanical tests revealed that dispersing Nb particles within the Mg matrix enhanced the composite's strength and hardness through load transfer, dislocation strengthening and grain boundary strengthening mechanisms. Furthermore, the even distribution of Nb reinforcements uniformly transferred load across the composite samples delaying fracture initiation and improving failure strain. Both pure Mg and Mg-Nb composites displayed a combination of brittle and shear fracture modes in their fracture behavior. The inclusion of 15 wt.% Nb significantly increased hardness (by 62%), compressive yield strength (by 89%), and failure strain (by 37.6%) compared to pure Mg.