Mechanical properties of directionally freeze-cast titanium foams

Titanium foams with aligned, elongated pores were created by directional freeze-casting of aqueous slurries of titanium powders, followed by ice sublimation and powder sintering. Increasing sintering times from 8 to 24 h and decreasing powder size from 20 to 10 μm resulted in improved densification within cell walls and decreased overall foam porosity, with a concomitant increase in compressive stiffness, yield strength and energy absorption. A simple model for foam stiffness and strength is in general agreement with experimental measurements of strength but overpredicts stiffness, probably because it does not take into account micro-plasticity occurring during measurements.