Al₂O₃-Ti functionally graded material prepared by spark plasma sintering for orthopaedic applications

Orthopaedic prostheses still suffer from limited lifetime which imposes revision surgery with the associated risks involved. This, to some extent, is related to the vulnerability of the biomaterials used for their fabrication that are commonly single-constituent and uniform. Therefore, hybrid biomaterials such as composites and functionally graded materials (FGMs) are being developed to overcome the shortcomings of available biomaterials. The present paper focuses on the study of the structural, physical and mechanical properties of a FGM made of alumina-titanium fabricated by spark plasma sintering (SPS). The corresponding composites of the individual FGM layer were also fabricated. After sintering, the structural, mechanical and physical tests were carried out. The microstructural analysis using X-ray diffraction revealed the presence of Ti₃Al and TiAl in the composites, particularly with the increase of titanium content. Scanning electron micrographs revealed good adhesion and bonding between the two phases and between the FGM layers. The hardness and bending strength of the composites and FGM samples were tested and it was found that the increase in amount of Ti volume fraction decreases these properties monotonically. Furthermore, the sintering behaviour and fracture mechanisms of the FGM sample were studied and discussed.