Effects of hydroxyapatite addition on the bioactivity of Ti-Nb alloy matrix composite fabricated via powder metallurgy process

Abstract

This study investigates the bioactivity of titanium-niobium-hydroxyapatite (Ti-Nb-HA) composite prepared by mechanical alloying and powder metallurgy with variable HA content from 0 to 15 wt.%. Increasing the HA content weakened the X-ray diffraction intensity of β phase along with the noticeable presence of α phase and phases of TiO2, and Ti2P. The composite displayed good bioactivity in Hanks’ Balanced Salt Solution (HBSS) with the highest bioactivity exhibited by the 15 wt.% HA after a 30-day immersion with observed additional phases of CaTiO3 and CaO. Signs of HA decomposition, which led to an enhancement in the bioactivity, were remarked. The dispersion of HA particles in the Ti-Nb alloy matrix accelerated the apatite formation based on the accumulation of Ca, P and O elements on the composite surface. The presence of OH− and PO43- denoted the formation of calcium phosphate (apatite) with a hydrophilic surface. Based on the immersion test, only the 15 wt.% HA composite experienced a weight loss while the other composites gained weight.