Directional freeze-casting-a process used in order to produce foams with elongated, aligned pores applied so far exclusively for ceramics-is demonstrated for a titanium foam. An aqueous slurry of <45 mum titanium powders is directionally solidified, resulting in a preform with elongated, aligned, dendrites of 0.2 wt percent agar solution, separated by interdendritic regions with high powder content. The preform is freeze-dried to remove the ice dendrites and sintered. The resulting titanium foams show 60 vol percent aligned pores (approx 0.1 mm width and several millimeters long) replicating the ice dendrites and separated by walls constructed by partially-sintered titanium powders. On the other hand, when large size powder (<125 mum) was applied, their larger size inhibits the formation of pure ice dendrites, in agreement with a theoretical model.
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