Synthesis of intermetallic NiAl by SHS reaction using coarse-grained nickel and ultrafine-grained aluminum produced by wire electrical explosion

Nickel aluminide NiAl was synthesized by using aluminum nanoparticles via the thermal explosion mode of the self-propagating high temperature synthesis (SHS). Differential scanning calorimetry (DSC) was used to investigate the reaction process and mechanism. It was found that the mode and mechanism of reaction strongly depended on the charateristics of aluminum nanoparticles that have small grain size, high surface areas, high stored-energies and low melting point. The initial reaction started from 470 degreesC. The SHS reaction was controlled by a competition between thermal and kinetic processes. With increasing green density and heating rate, the ignition temperature decreased. With proper heating rates, a fine (< 10 mum), monophased, homogeneous NiAl Compound was obtained. (C) 2002 Elsevier Science Ltd. All rights reserved.