Development of Wear-Resistant Cu-10Cr-3Ag Electrical Contacts with Nano-Al2O3 Dispersion by Mechanical Alloying and High Pressure Sintering

摘要

Cu-10Cr-3Ag (wt pct) alloy with nanocrystalline Al2O3 dispersion was prepared by mechanical alloying and consolidated by high pressure sintering at different temperatures. Characterization by X-ray diffraction and scanning electron microscopy or transmission electron microscopy shows the formation of nanocrystalline matrix grains of about 40 nm after 25 hours of milling with nanometric (<20 nm) Al2O3 particles dispersed in it. After consolidation by high pressure sintering (8 GPa at 400 °C to 800 °C), the dispersoids retain their ultrafine size and uniform distribution, while the alloyed matrix undergoes significant grain growth. The hardness and wear resistance of the pellets increase significantly with the addition of nano-Al2O3 particles. The electrical conductivity of the pellets without and with nano-Al2O3 dispersion is about 30 pct IACS (international annealing copper standard) and 25 pct IACS, respectively. Thus, mechanical alloying followed by high pressure sintering seems a potential route for developing nano-Al2O3 dispersed Cu-Cr-Ag alloy for heavy duty electrical contact.