Influence of Ag impurity doping on the microstructure and hardness of alumina dispersion strengthened copper alloys

Dispersion strengthened copper alloys (DSC) with high strength and high conductivity are widely used in automobile and electronics industries. In the present investigation the influence of Ag impurity doping on the mechanical properties of the alumina dispersion strengthened copper alloys was studied by mechanical alloying, and the influence mechanism was discussed subsequently. Alumina dispersion strengthened copper alloys powder was fabricated by high-energy ball milling. XRD results showed that the high-energy ball milling can dissolve Al2O3 into Cu matrix. As-milled powder was consolidated by cold-pressing and sintered at 860 degrees C, 900 degrees C, 940 degrees C and 980 degrees C, respectively. It was shown that the addition of Ag can significantly improve the hardness of Cu alloys. SEM characterization showed that the size of Al2O3 particles in Cu-Al2O3 sintered at 980 degrees C was about 200nm, which is bigger than the initial size (about 150 +/- 30nm) of Al2O3 particles; and the size of Cu-Al2O3-Ag sintered at 980 degrees C and 860 degrees C was about 100nm and 30nm respectively. The difference in alumina size was considered as the result of Ag segregation at Cu/Al2O3 interface. The segregation of Ag at Cu/Al2O3 interface can suppress the growth of Al2O3, which will significantly improve the hardness of Cu alloys. (C) 2011 Published Elsevier Ltd.