Titanium alloys find extensive use in the biomedical field, including applications in the
form of a porous structure as a scaffold material for bone repair. Scaffold materials have
demanding mechanical and biocompatibility requirements, which vary depending on the
orthopaedic application. These requirements are determined by both the porous
macrostructure of the foams and the strut wall microstructure. Therefore techniques are
needed to characterise these structural features and relate them to the mechanical and
physical properties. In this thesis new methods were developed to both manufacture
titanium alloy foams and characterise them.
Non- destructive X-ray micro-computed tomography (μCT) methods were employed to
characterise the pore and interconnect size. The pore and interconnect size dominates the
flow properties (permeability) of open-foam structures. Thus, μCT data was meshed and
computational fluid dynamics analysis was performed to predict permeability. Direct
finite element modelling, continuum micromechanics and analytical models of the foam
were employed to characterise the elasto-plastic deformation behaviour. Pore anisotropy
was quantified and related to the yield stress anisotropy, allowing identification of initial
pore collapse. These results were validated against experimental measurements.
Finally, the conventional production method of porous titanium is achieved through a
costly multi-step powder metallurgical (PM) route. A new, potentially low cost, method
was developed to produce porous titanium with properties similar or better than the
existing titanium foam from a ceramic precursor via an electrochemical route. Two steps
were involved: (1) preparing the ceramic precursor foam via a gel-casting route; and (2)
reducing the oxide electrochemically via the FFC (Fray, Farthing and Chen) Cambridge
process. The results of this preliminary study are very promising, with the foams
produced via this method demonstrating mechanical and physical properties comparable
to conventionally manufactured foams.