Sintering mechanism of large-scale ultrafine-grained copper prepared by SPS method

Spark Plasma Sintering (SPS), as a novel sintering technique, is used for preparing large-scale ultrafine-grained copper. According to the evolution of the microstructure, the sintering process is divided into four stages: activation and refining of the powder, formation and growth of the sintering neck, rapid densification and plastic deformation densification. Only when the above mentioned sintering stages proceed in turn and are all fully completed, the high quality bulk compact can be obtained. For the fine copper powder, the optimized sintering parameters are selected as follows: sintering temperature of 750 °C, initial pressure of 1 MPa, holding pressure of 50 MPa, heating rate of 80 °C/min, and holding time of 6 min. Both the tensile strength and the elongation of the ultrafine-grained copper are all improved due to the fine crystal and the submicron twins.