Microstructural characterization and interactions in Ti- and TiH2-hydroxyapatite vacuum sintered composites

Titanium/hydroxyapatite (HAP) composites are candidate materials for biomedical applications as implants and hard tissue substitutes since they combine the good mechanical properties and biocompatibility of Ti with the excellent HAP bioactivity and osteointegration. In powder metallurgy processing of these composites, HAP decomposition promoted by Ti during powder sintering is found. In a previous work Ti-50v%HAP greens of 60% theoretical density (dT) were vacuum sintered at 1150 °C and formation of CaO and Ca4O(PO4)2 (TTCP) resulting from the HAP decomposition, as well as Ti4P3 at the Ti/HAP interfaces was obtained. In the present work those composites are compared with similar ones processed from TiH2 as a substitute for Ti which were also vacuum sintered at 1150 °C from greens with 60 to 86%dT. For the lower %dT, the compounds formed were CaO, TTCP and Ti4P3 and for the higher %dT ones, besides those same products, CaTiO3, Ti5P3 and a phase containing Ti, Ca and P were detected