脱β层梯度硬质合金的制备及组织结构

Preparation and microstructure of graded cemented carbides with cubic carbide free layer

采用1步烧结法,在原料粉末中添加中颗粒Ti(C,N)的情况下制备表面含脱β层的梯度结构硬质合金。分别采用扫描电镜(SEM)、X射线衍射(XRD)及能谱技术(EDS)分析合金样品的微观组织、相组成及成分分布。结果表明,在1 420℃下真空烧结时,初始成分不含Ti(C,N)的合金样品的组织为均质结构,由WC,Co基粘结相及(Ti,W)C三相组成;初始成分含有Ti(C,N)的合金样品表层形成了脱β层,脱β层中仅存在WC,Co基粘结相2相,芯部的组织除WC,Co基粘结相及(Ti,W)C 3相以外,还存在少量近球形未溶解的Ti(C,N)核心。脱β层既是1个缺立方相层,也是1个富钴层。

Cemented carbide with cubic carbide free layer（CCFL） in the surface was fabricated by one-step sintering procedure adding middle particle Ti（C,N） powder in raw materials.The microstructure,phases composition and element distribution of the cemented carbides were investigated by SEM,XRD and EDS.The results show that,when sintering in vacuum at 1 420 ℃,homogeneous structural cemented carbides composed of WC,Co and（Ti,W）C phases can be synthesized with no Ti（C,N） in initial composition;the graded cemented carbide with CCFL can be obtained with the initial composition containing Ti（C,N）,of which there are only two phases including WC and Co based binder phase in the surface zone,and there are four phases of WC,Co based binder phase,cubic solid solution（Ti,W）C and undissolved spherical Ti（C,N） nucleus in the core zone.Moreover,the CCFL is also a layer enriched in cobalt.