Two-step hot-pressing sintering of composite WC-40%Al₂O₃ compacts

The WC-40%Al₂O₃ composite powder synthesized by high-energy ball milling was used as raw material followed by two-step hot-pressing sintering (TSS).The first step sintering at a constant heating rate with a higher temperature T₁ to obtain an initial high density and guarantees the disappearance of supercritical pores, while the other pores become unstable. The second step was held at lower temperature T₂ by isothermal for a period of hours to increase bulk density with a limited grain size. The phase and microstructure of the composite were characterized by XRD, SEM and SPM technology. The present work dealt with the influence of deliberate temperature and holding time at second step, which had been well documented by orthogonal analysis, on microstructure and mechanical properties of WC-40%Al₂O₃ nanocomposite. The results show that when the sample sintered at 1600 ℃(T₁) and holding 6 h at 1450 ℃(T₂) obtains a relative density of 99.03%, Vickers hardness of 18.36 GPa, a fracture toughness of 10.4 MPa·m^1/2 and a bending strength of 1162.1 MPa.