High-resolution electron microscopy study of spontaneous alloying in gold clusters

The alloying behaviour of copper atoms into gold clusters has been studied by high-resolution electron microscopy. Preparation of nanometre-sized gold clusters and subsequent copper deposition onto the gold clusters has been carried out with the use of a miniature double-source evaporator that has been directly set at the tip of a specimen holder. Upon the deposition of copper, nanometre-sized gold clusters quickly changed into Au-Cu solid solution clusters even at ambient temperature. It has been confirmed that such spontaneous alloying takes place not via a quasi-melting process but via a purely solid-state process.