不含氮原料制备脱β层梯度硬质合金的机理研究  

Study on the Mechanism of Preparation of De-β-layered Gradient Cemented Carbide with Nitrogen-free Raw Material

作　　者：杨晋伟 史留勇[1] 周腾[1] 张先满[1] 罗洪峰[1] YANG Jin-wei SHI Liu-yong ZHOU Teng ZHANG Xian-man LUO Hong-feng(Mechanical and Electrical Engineering College, Hainan University, Haikou 570228, Chin)

机构地区：[1]海南大学机电工程学院,海南海口570228

出　　处：《稀有金属与硬质合金》2017年第4期76-81,共6页Rare Metals and Cemented Carbides

基　　金：国家自然科学基金资助项目(51404084)

摘　　要：采用不含氮原料及微压氮化+真空脱氮烧结工艺制备脱β层梯度硬质合金,并采用扫描电镜及自带能谱仪、电子探针微区分析技术分析不同烧结阶段下硬质合金样品的微观组织结构及成分分布,研究烧结过程中微观组织结构演变规律,总结缺立方相层的形成机制,同时分析富Co层的形成机理。结果表明:在微压氮化阶段,硬质合金中的TiC相被氮化生成了Ti(C,N)相;在之后的脱氮烧结阶段,Ti(C,N)相溶解在液相中,并且发生氮钛的耦合扩散,导致缺立方相层的形成。Co元素的空位扩散及液相迁移机制联合作用形成了富Co层;冷却过程中液相迁移导致了富Co层内部不同区域之间Co含量的差异。De-β-1ayered gradient cemented carbide was prepared by micro-pressure nitrification and vacuum denitrification sintering with nitrogen-free raw material. The microstructure and element distribution of al- loy samples at different sintering steps were analyzed by SEM, EDS and EPMA techniques, their micro- structure evolution rules during sintering were investigated,and the formation mechanisms of cubic carbide free layer and Co-rich layer were summarized. The results indicate that TiC phase in the cemented carbide is nitrided to Ti（C,N） phase during micro-pressure nitrification. And then the dissolution of Ti（C,N） into the liquid phase and the N-Ti coupling diffusion result in the formation of cubic carbide free layer during denitrification sintering. The combined action of Co vacancy diffusion and liquid migration is responsible for the formation of Co-rich layer. Liquid migration during cooling results in the difference of Co content in dif- ferent regions of Co-rich layer.

关 键 词：梯度硬质合金 不含氮原料 缺立方相层 富Co层 形成机理 

分 类 号：TF125.3[冶金工程—粉末冶金]