Influence of NbC and VC on microstructures and mechanical properties of WC–Co functionally graded cemented carbides
Influence of NbC and VC on microstructures and mechanical properties of WC–Co functionally graded cemented carbides
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DOI：
10.1016/j.matdes.2015.10.156
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发表时间：
2016-01
影响因子：
8.4
通讯作者：
Xiaofen Li;Y. Liu;Wei Wei-Wei;M. Du;Kaiyang Li;Jianhua Zhou;Fu Kun
中科院分区：
文献类型：
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作者：
Xiaofen Li;Y. Liu;Wei Wei-Wei;M. Du;Kaiyang Li;Jianhua Zhou;Fu Kun
功能梯度硬质合金（FGCC）通常具有粗晶粒表面层。为了细化WC晶粒，提高其力学性能，在WC-6Co FGCC中加入VC和NbC作为晶粒长大抑制剂。研究了WC的晶粒长大动力学，测试了WC的室温和高温力学性能。结果表明，NbC和VC的加入减小了梯度层的厚度。VC的加入使梯度层的厚度减少一半，而NbC的加入效果较差。NbC和VC的加入通过抑制WC颗粒在预烧结和渗碳过程中在Co相中的吸附/脱附过程来细化晶粒，且VC比NbC更有效。NbC的加入提高了FGCC的横向断裂强度，这是由于细化了FGCC的显微组织，并在Co相中产生了固溶强化。NbC和VC的加入提高了FGCC的抗氧化性，使其组织更加均匀和细化，从而提高了FGCC的高温硬度。
Functionally graded cemented carbides (FGCCs) usually have a coarse-grained surface layer. In order to refine the grain size of WC and to improve the mechanical properties, VC and NbC as grain growth inhibitors, were added to WC–6Co FGCCs. The grain growth kinetics of WC was investigated, and both the room temperature and high temperature mechanical properties were tested. The results show that the additions of NbC and VC reduce the thickness of the gradient layer in FGCCs. The addition of VC reduces the thickness of the gradient layer by half, while that of NbC is less effective. The additions of NbC and VC refine the grain size by suppressing the adsorption/desorption processes of WC grains in Co phase during the pre-sintering and the carburizing processes, and VC is more effective than NbC. The addition of NbC increases the transverse rupture strength of FGCCs, because of the fine microstructure, and the solution strengthening in Co phase. Both the additions of NbC and VC increase the high temperature hardness of FGCCs due to improved oxidation resistance, more homogeneous and finer microstructures.