不同细WC添加量对板状硬质合金显微组织和力学性能各向异性的影响  

Effects of Fine WC Powder Addition on Microstructure and Anisotropy of Mechanical Properties of Plate-like Grained Cemented Carbides

作　　者：丁青军 郑勇[1] 柯峥 严永林 周伟[1] Ding Qingjun;Zheng Yong;Ke Zheng;Yan Yonglin;Zhou Wei(College of Material Science and Technology,Nanjing University of Aeronautics and Astronautics,Nanjing Jiangsu 210016,China;Suzhou Xinrui Alloy Tools Co.,Ltd.,Suzhou Jiangsu 215121,China)

机构地区：[1]南京航空航天大学材料科学与技术学院,江苏南京210016 [2]苏州新锐合金工具股份有限公司,江苏苏州215121

出　　处：《硬质合金》2019年第6期414-422,共9页Cemented Carbides

基　　金：国家自然科学基金资助项目：Mo2FeB2基金属陶瓷的显微组织形成机理与调控（编号：51674148）;江苏省第十批“六大人才高峰”高层次人才资助项目（XCL-029）;江苏高校优势学科建设工程资助项目（PAPD）

摘　　要：本文以真空烧结法制备了显微组织中含有板状粗WC晶粒的WC-Co硬质合金。用三点弯曲法、洛氏硬度计、压痕法分别测得试样的抗弯强度、硬度和断裂韧性,并通过XRD,SEM等手段研究不同细WC添加量对板状硬质合金显微组织及力学性能各向异性的影响。结果表明:随着细WC添加量的增加,板状硬质合金中板状粗WC晶粒定向排列程度越弱,板状硬质合金在垂直于压制方向和平行于压制方向的显微组织差异逐渐减小;当细WC的添加量为35%(质量分数,下同)和45%时,硬质合金中板状粗WC晶粒基本是随机分布,不同方向上的显微组织差异较小。随着细WC添加量增加,硬质合金垂直于压制方向和平行于压制方向上的强度和硬度增加,断裂韧性下降,并且两个方向上的力学性能差异逐渐减小;当细WC的添加量为35%和45%时,两个面上的力学性能基本一致;当细WC的添加量为35%时,硬质合金的综合力学性能较佳。Cemented carbides with plate-like WC grains were fabricated by vacuum sintering. The mechanical properties of the prepared cemented carbides, such as transverse rupture strength(TRS), hardness(HRA) and fracture toughness(KIC), were tested by three-point-bending, rockwell apparatus, plamqvist indentation toughness measurement,respectively. The effects of fine WC powder addition on microstructure and anisotropy of mechanical properties were studied by X-ray diffraction(XRD) and scanning electron microscopy(SEM). Results show that with the increase of the fine WC powder addition, the extent of orientation of plate-like WC grains decreases, and the differences in the microstructure between different planes perpendicular to and parallel to the pressing direction gradually decrease. When fine WC powder additions are 35% and 45%(mass fraction), plate-like WC grains are randomly distributed, and there are few differences in the microstructure between two planes perpendicular to and parallel to the pressing direction. With the increase of the fine WC powder addition, hardness and strength increase and fracture toughness decreases on two planes perpendicular to and parallel to the direction of pressing, and the differences in the mechanical properties between two planes decrease. When fine WC powder additions are 35% and 45%, the mechanical properties on the plane perpendicular to the direction of pressing are almost the same as those on the plane parallel to the direction of pressing. When fine WC powder addition is 35%, the cemented carbide exhibits the good comprehensive mechanical properties.

关 键 词：硬质合金 各向异性 板状WC晶粒 细WC 显微组织 力学性能 

分 类 号：TG1[金属学及工艺—金属学]