Study of structure and properties of dual-size grain copper matrix composites prepared by NbC and rare earth element La

Copper matrix composites with NbC content of 1 wt.% and La content of 0.02 wt.%, 0.04 wt.%, 0.06 wt.%, and 0.08 wt.% were prepared by high-energy ball milling and spark plasma sintering using rare earth element La, ceramic particle NbC, and electrolytic copper powder as raw materials. The effects of different La content on the properties of NbC-Cu composites were discussed by observing the microstructure of La-NbC-Cu composites and testing the hardness and conductivity. When the content of La is 0.06 wt.%, the La-NbC-Cu composite has a hardness of 62 HV and a good conductivity of 76.5% IACS. At this time, the internal stress of the material is reduced and ultrafine grains appear. Then, with the increase of La element, when the content of La is 0.08 wt.%, the hardness of copper matrix composites decreases due to the enrichment of La atoms on the surface of the reinforced phase.