A Study on Rare Earth-Modified Co-Based Composite Powder and Its Effects on the Microstructure and Properties of Cemented Carbide

A Co-based composite powder, doped with rare earth Y, was crafted through a series of processes involving spray-drying, calcination, and low-temperature reduction. This powder was then blended with tungsten carbide (WC) powder and subjected to ball-milling. The resultant mixture was consolidated into a robust Y-doped WC-Co cemented carbide via the process of spark plasma sintering (SPS). The outcomes demonstrate that incorporating rare earth Y into Co powder to form a Co-Y₂O₃ composite powder via an innovative spray-drying, calcination, and low-temperature reduction process ensures uniform distribution of Y in the Co matrix. This uniform distribution refines the alloy's grain structure during subsequent sintering, leading to enhanced performance. Within a specific range, increasing the Y content improves the overall alloy properties. It is notable that at a Y content of 1.5%, the alloy's properties reach a state of stability, characterized by a density of 98.91%, a maximum hardness of 2120 Hv₃₀, and a fracture toughness of 8.24 MPa·m^1/2. The novel Y incorporation method has been shown to enhance the strength of the binder phase, impede the growth of WC grains, and thereby lead to a substantial improvement in the overall performance of the cemented carbide.