Effect of rare earth oxide addition on microstructures of ultra-fine WC–Co particulate reinforced Cu matrix composites prepared by direct laser sintering

This paper presents a detailed investigation into the influence of the rare earth (RE) oxide (La2O3) addition upon the densification and the resultant microstructural characteristics of the submicron WC–Co particulate reinforced Cu matrix composites prepared by direct laser sintering. It is found that the relative density of the laser sintered sample with 1 wt.% La2O3 addition increased by 11.5% as compared with the sample without RE addition. The addition of RE element favored the microstructural refinement and improved the particulate dispersion homogeneity and the particulate/matrix interfacial coherence. The metallurgical functions of the RE element in improving the sinterability were also addressed. It shows that due to the unique properties of RE element such as high surface activity and large atomic radius, the addition of trace RE element can decrease the surface tension of the melt, resist the grain growth coarsening and increase the heterogeneous nucleation rate during laser sintering.