A comparative study on compressive deformation and corrosion behaviour of heat treated Ti4wt%Al foam of different porosity made of milled and unmilled powders.

ABSTRACT

Ti4wt%Al alloy foams of various porosities were prepared using milled and unmilled powders through space holder technique. Crystallographic and morphological change in milled powder compared to the unmilled one were also examined. Space holder content was varied to get foams of different porosities. After sintering, foams were thermally oxidized through heat treatment and characterised in terms of their pore size, pore morphology, pore interconnectivity, phase formation and compressive deformation behaviour. It was observed that plastic collapse stress, elastic modulus, plateau stress and energy absorption capacity are strong function of porosity and these are higher for the foam made of milled powder (Mf) than those of the foam made of unmilled one (Uf). Corrosion behaviour of these foams were examined. Open circuit potential, Tafel plot and electrochemical impedance spectroscopy confirm that Mf has higher corrosion resistance than Uf for the same porosity level. Also, with increasing porosity, corrosion resistance of the foam samples reduces.