2009 Volume 50 Issue 11 Pages 2609-2614
Porous Al3Ti/Al composite was fabricated by a combustion foaming process, which makes use of exothermic reactions between titanium, aluminum and boron carbide powders. Boron carbide powder was used as an exothermic agent to increase the heat of reaction. Fundamental combustion foaming behavior and effects of processing parameters (Al/Ti blending ratio, addition of exothermic agent and powder compacting pressure) on the foaming behavior were investigated. Combustion foaming took place over temperature ranges between melting points of aluminum and Al3Ti. Exothermic agent addition turned out to be effective to increase the porosity of porous Al3Ti/Al composite. Relative density of the precursor was an important factor, which needed to be higher than a threshold level (0.67) to prevent extremely inhomogeneous pore morphology. By conducting hot extrusion to the precursor, both pore size and porosity were increased. As a result of compressive test, high plateau stress and absorbed energy were achieved by increasing Al/Ti mole blending ratio from 4.0 to 7.0.
