Mechanochemical Synthesis of Intermetallic Compounds in the Gallium–Iridium System

Resumo

The interaction between a solid inert metal (Ir) and an active liquid metal (Ga) during mechanical activation in a high-energy planetary mill is studied by X-ray diffraction and scanning electron microscopy with EDS-apparatus for high-resolution energy dispersive X-ray microanalysis. The influence of mechanical activation conditions on the formation of Ga_xIr_y intermetallic compounds and Ga_xIr_y/Ir composites and on their solubility in various acids is investigated. Being a surfactant for iridium, gallium propagates along the grain boundaries of polycrystalline iridium particles during mechanical activaiton and, hence, sharply decreases their strength. As a result of strong mechanical deformation during activation, the contact surface area between the solid and liquid metals, where the intermetallic compounds form intensely, increases sharply. As a result of treatment of the products of mechanical activaiton by a mixture of concentrated hydrochloric and nitric acids, iridium (>30%) from passes into an acid solution and forms H_xIrCl_y complex compounds, which can interact with bases to form soluble complex salts.