采用热压烧结制备了不同亚微米级c-BN含量的(Ti,W)C基复合金属陶瓷刀具材料,用热场发射扫描电子显微镜及能谱仪、透射电子显微镜和X射线衍射仪对材料的微观组织结构和力学性能进行了研究.结果表明:添加c-BN可改善材料的力学性能,当c-BN含量为1.5wt%时,(Ti,W)C基复合金属陶瓷刀具的性能最优,其抗弯强度达到917MPa,断裂韧性为9.27MPa·m1/2,维氏硬度为20.64GPa;适量c-BN可起到细化晶粒、减少气孔缺陷和提高致密度的作用,复合材料由沿晶断裂为主转变为穿晶断裂为主;在c-BN复合(W,Ti)C基金属陶瓷刀具材料中,主要的增韧补强机理有晶粒细化、颗粒桥联、裂纹偏转和裂纹分叉.
(Ti,W)C based composite cermet tool materials with different c-BN contents are prepared by hot-pressing sintering.The microstructures and mechanical properties of the composites are studied by using field emission scanning electron microscope and energy dispersive X-ray spectrometer,transmission electron microscope and X-ray diffractometer.The results show that the addition of c-BN can improve the mechanical properties of the composites.When the content of cBN is 1.5wt%,the mechanical properties of (W,Ti) C-based composite cermets are the best.Its flexural strength reaches 917MPa,fracture toughness 9.27MPa·m1/2 and Vickers hardness 20.64GPa.It is found that the proper content of c-BN can refine the grain effectively,improve the density and reduce the defects such as cavities.With the addition of c-BN,the fracture form of composite can change from intergranular fracture to transgranular fracture,the fracture mode changes can effectively improve the mechanical properties of composite materials.In c-BN composite(W,Ti) C matrix cermet tool materials,the main toughening mechanism is grain refinement,particle bridging,crack deflection and crack bifurcation.