Development of nano-structure Cu–Zr alloys by the mechanical alloying process

Cu–Zr alloys have many applications in electrical and welding industries for their high strength and high electrical and thermal conductivities. These alloys are among age-hardenable alloys with capability of having nano-structure with high solute contents obtainable by the mechanical alloying process. In the present work, Cu–Zr alloys have been developed by the mechanical alloying process. Pure copper powders with different amounts of 1, 3 and 6 wt% of commercial pure zirconium powders were mixed. The powder mixtures were milled in a planetary ball mill for different milling times of 4, 12, 48 and 96 h. Ball mill velocity was 250 rpm and ball to powder weight ratio was 10:1. Ethanol was used as process control agent (PCA). The milling atmosphere was protected by argon gas to prevent the oxidation of powders. The milled powders were analysed by XRD technique and were also investigated by SEM observations. Lattice parameters, crystal sizes and internal strains were calculated using XRD data and Williamson–Hall equation. Results showed that the lattice parameter of copper increased with increasing milling time. The microstructure of milled powder particles became finer at longer milling time towards nano-scale structure. SEM observations showed that powder particles took plate-like shapes. Their average size increased initially and reached a maximum value then it decreased at longer milling times. Different zirconium contents had interesting effects on the behavior of powder mixtures during milling.

Research highlights▶ In the present work, copper based zirconium alloys were developed by mechanical alloying method. ▶ It was possible to produce alloys with Zr contents much more than equilibrium content, which showed high hardness after age hardening stage. ▶ Zr content had a profound effect on the behavior of the alloys.