Al and Ru nanoparticles as precursors for Ru–Al intermetallics

Abstract

Intermetallic compounds of Al and Ru are exhibiting promising physical and chemical properties, such high-temperature strength and oxidation resistance. Compacted micron-sized Ru and Al powders or multilayer systems are usually the starting points for their synthesis. Nanoparticles are rarely applied in the preparation of such intermetallic compounds. Here we present the preparation of Ru aluminides starting from Al and Ru nanoparticles. Al particles showing diameters as small as 125 nm were synthesized via thermal decomposition of triisobutylaluminum in refluxing phenylether, while the Ru nanoparticles were prepared by thermal decomposition of Ru3(CO)12 at 300 °C in the presence of oleylamine. Both synthetic steps can be carried out subsequently in a one pot reaction and the resulting powders consisted of well-dispersed and intermixed Ru and Al particles. Upon thermal treatment of the mixed particles in an Ar atmosphere we observed the formation of multiphase products mainly consisting of Ru, RuAl, Ru2Al3 and RuAl2. The phase fractions were found to be dependent on the sample mass used for the reaction and the Al:Ru ratio. Ignition temperatures of the self-propagating reaction could be decreased to 300 °C in an ambient atmosphere. Accordingly, the preparation of Ru–Al intermetallic compounds starting from wet chemically synthesized Al and Ru nanoparticles was found to be readily possible, particularly under an atmosphere of ambient air.