Designing compressive properties of titanium foams

Abstract

Titanium foams were produced by optimizing a relatively cheap method, sintering under flowing high purity argon gas with fugitive space holder. Removal of the space holder was conducted by dissolution in hot deionized water which renders it possible to minimize contamination of titanium. Titanium foams having various densities between 20 and 70% were manufactured and systematically characterized. Pore sizes varying from a few microns up to 2 mm were obtained. Compatibility with well known porosity–mechanical property formulations of cellular solids was investigated. Pore sizes in the investigated range were found to have a negligible effect on the elastic portion of compressive stress–strain diagram. High strain rate tests revealed that increasing the strain rate increases compressive strength of the titanium foams produced. The onset strain of densification of the produced titanium foams was determined by the recently developed energy absorption efficiency method. The energy absorbed per unit volume was then calculated by referring to the pre-determined onset strain of densification. A plot of energy absorbed per unit volume (E_A) as a function of relative density (ρ/ρ_s) at various strains (%ε) suggested that the data could be fitted to an equation of the form E_A = A(%ε)^B(ρ/ρ_s)^C, where A, B and C are constants, for both fine- and coarse-pored titanium foams.