Morphological Control of Porous Structure in Al-Ti Intermetallics Foam Manufactured by Reactive Precursor Process

Abstract

In this paper, a novel processing method (reactive precursor method) to manufacture high-melting point porous Al-Ti intermetallics is investigated. Especially, morphological control of porous structure is focused. In the reactive precursor process, precursors are made by blending aluminum and titanium powders. The precursor is heated to ignite an exothermic reaction (so called “combustion reaction”) between the elemental powders. Pore formation is a well-known intrinsic feature of the combustion reaction, and we tried to control the pore morphology. Fundamentally, the closed-cell structure can be obtained when the maximum temperature during the reaction exceeds the melting point of the reaction product. By blending the exothermic agent powder in the precursor, the maximum temperature is increased and the reaction products are melted. The porosity is controlled by the maximum temperature. In contrast, an open-cell porous structure can be obtained when the maximum temperature is below the melting point of the reaction product. Microwave heating turned out to be an effective method to create an open cell structure. A powdery substance that does not react with other elemental powders (heat-absorbing agent powder) decreases the temperature during the reaction. Closed, open and bimodal-sized open pores have been achieved by the reactive precursor process so far.