Formation of nickel aluminides under shock-wave loading

Recently we reported the synthesis of nickel aluminides in a mixture of elemental aluminum and nickel powders under explosive shock-wave loading. The alloy products were found to be readily synthesized and controlled by shockloading conditions. A notable microstructural feature was the presence of unusually small Ni3 Al crystallites having a grain size of about 5 nm. They were found in a region of high shock-induced temperature where there were extensive alloying reactions. In this report we present the observation of similar crystallites in a low temperature region where observed reactions were sparse and localized. The structures of these crystallites were tentatively identified as those of NiAl and Ni2Al3.