A Study on Effect of Processing Parameters on Electrical Conduction and Micro-hardness of Nano-crystalline Cu-5%at Ta Alloy

At the present study, the mechanical alloying method was used to produce the nanocrystalline Cu-5Ta alloy. In order to achieve a specimen with desirable properties, effects of size of milling ball, atmosphere and temperature of sintering were investigated on crystalline structure, electrical conduction and microhardness of specimen. The microstructural studies indicated that a finer crystallite size was attained when the complex size of milling balls being composed of 10 and 5 millimeters was applied rather than simple one of 10 millimeters. After milling, cold press and subsequent sintering were done under different atmospheres such as nitrogen, argon and vacuum at temperature of 550C. The sintered specimen under vacuum showed the better properties compared to the others. The further evaluations on specimen properties was conducted by sintering at temperatures of 700 and 850C under vacuum. The results indicated that with increasing the sintering temperature, electrical conduction and microhardness increase. Overall, the specimen milled by the complex ball size and sintered at temperature of 850C under vacuum experienced a electrical condition of 15.7% IACS and microhardness of 196.2 HV which was the best conditions to produce Cu5Ta.