Effects of Rare-Earth Oxides on the Microstructure and Mechanical Properties of Regenerated Cemented WC-12Co-2Ni Carbide

The effect of La₂O₃ and Y₂O₃ additions on the improvement of regenerated cemented carbide properties was investigated. The WC-Co powder recycled by the zinc melting method was used as a raw material, and five alloys were prepared by conventional powder metallurgy process by adding La₂O₃ and Y₂O₃ with 0, 0.3, and 0.6 wt.%, separately. The results show that they have a certain effect on the carbide compactness, but it is not obvious. When the La₂O₃ or Y₂O₃ content is less than 0.3 wt%, the hardness of regenerated cemented carbide will be slightly increased and then significantly decreased. A rare-earth oxide exhibits significant improvement of fracture toughness and transverse rupture strength, and the performance of carbide with Y₂O₃ is better than that with La₂O₃. When 0.3 wt.% Y₂O₃ is added, integrated mechanical properties of regenerated cemented carbide are excellent: hardness is 1720 HV30 kgf, fracture toughness is 8.41 MPa ·m^1/2, and rupture strength is 1653 MPa.