Structure of Al2Au Intermetallic Compound Obtained by Mechanochemical Synthesis

Abstract

The structure of Al₂Au intermetallic compound mechanically synthesized from a nanoscale gold powder and aluminum particles of about 0.5 mm in size has been studied by X-ray diffraction and transmission and scanning electron microscopy. It has been established that the intermetallic compound is formed as a powder with a particle size of 0.3–3 μm. In addition to intermetallic compound, some aluminum has been found in the powder, along with traces of gold and aluminum oxide Al₂O₃, and the appearance of an amorphous phase has been registered. The microstructure of compacts formed from the obtained powder has been studied, and heat treatments have been carried out. It has been found that compacting and subsequent annealing contribute to the agglomeration of intermetallic particles. Increasing the treatment temperature to 600°C results in the refinement of the structural elements as a result of their cracking in the surface layer. Compacts that are dark purple in their original state acquire a color ranging from pink to dark red as a result of annealing. After heat treatment, the presence of Al₂O₃, as well as of intermetallic phases enriched in gold (AlAu and AlAu₄), has been detected in compacts in addition to the intermetallic compound Al₂Au.