Self-propagating high-temperature synthesis of nanostructured titanium aluminide alloys with varying porosity

Metallic foams were synthesized by means of a self-propagating high-temperature reaction producing a highly porous solid metal alloy with customizable material properties. Nanoscale aluminum (nAl) and nanoscale titanium (nTi) particles were mixed with either nanoscale aluminum passivated with a gasifying agent such as perfluoroalkyl carboxylic acid (C ₁₃F₂₇COOH) or polytetrafluoroethylene (Teflon) (C ₂F₄)_n particles and pressed into pellets. These samples were then ignited with a laser producing a reaction product composed of an AlTi alloy that has a highly porous structure. Objectives of this study were to use combustion synthesis to create a functionally graded porous AlTi alloy and identify correlations between the product microstructure and parameters such as type and amount of gasifying agent present in the reactants. Photographic data allowed interpretation of the reaction propagation while characterization of the final product indicated porosity and morphology. Results from this study may have applications in biomaterial development by tailoring porosity throughout the matrix.