Titanium with controllable pore fractions by thermo reversible gelcasting of TiH2

Thermoreversible gelcasting, a near-net-shape processing technique, is demonstrated here for titanium. The gelcasting system is composed of TiH2 particles suspended in a triblock copolymer gel that behaves as a viscous liquid above 56 degrees C and an elastic solid at room temperature, a temperature-dependent transition that is fully reversible when solvent is present. Organic pyrolysis to remove the gel followed by vacuum sintering to density the Ti powders (produced by decomposition of the hydride) results in titanium with near full density and low contamination. Incorporation of polypropylene and poly(methyl methacrylate) space-holder particles into the gel results in titanium with controlled porosities up to 44 vol.% and with low contamination. These foams exhibit tailorable stiffness and strength, together with excellent compressive ductility and energy absorption. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.