Microstructure and Mechanical Properties of a Cu-Pd-Ag Alloy Wire with Aging Treatment

Cu-Pd-Ag alloy is widely used in electronic device applications due to its relatively low electric resistance. To obtain higher strength wire, age-hardening is usually conducted to this alloy wire. However, the detailed hardening mechanism of Cu-Pd-Ag alloy was not clarified enough. In the present paper, we investigated the microstructure and hardness of the Cu-Pd-Ag alloy wire with aging treatment. Original alloy contained many rods with an Ag-rich alpha phase extended along the wire direction in a Cu-rich alpha phase matrix. After heat treatment of 623K with 1 hour, the matrix was transformed to the beta phase contained many elongated alpha(2) phases as nano-lamellar structure. Many beta' phase precipitated in the rods. Hardness measured with nano-indentation test showed that the matrix had a higher value than that of the rods. In the Cu-Pd-Ag alloy wire, the nano-lamellar structure of the matrix was revealed to contribute to the hardening of the wire.