Directional migration behavior of cerium during sintering process of mischmetal doped cemented carbide
Directional migration behavior of cerium during sintering process of mischmetal doped cemented carbide
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DOI：
10.1007/s11771-008-0002-2
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发表时间：
2008-02
影响因子：
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通讯作者：
Zhang Li;C. Shu;Xiong Xiang-jun;Yu Xian-wang;Wang Yuan-jie
中科院分区：
文献类型：
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作者：
Zhang Li;C. Shu;Xiong Xiang-jun;Yu Xian-wang;Wang Yuan-jie
考虑到合金中稀土添加量非常微量，采用扫描电镜（SEM）和能谱仪（EDXS）三种观察方法，研究了高活性混合稀土（RE，含镧和铈）掺杂低碳含量WC-8%Co-0.048%RE（质量分数）合金烧结过程中稀土的存在形态和行为。讨论了铈的定向迁移过程和机制。首先，观察烧结皮(表面)。结果表明，烧结皮上存在分散分布的含铈氧化物，且这些铈富集位置处的镧非常微量。其次，观察抛光断面，识别合金中的含镧相/微区。最后，基于硬质合金的断裂是由显微组织中的异相或其他缺陷引起的事实，观察断裂表面并识别出距表面约260μm的断裂源中的含铈相/微区。这些综合观察结果充分揭示了以下事实：在烧结过程中，镧和铈分离，并且铈主要向表面迁移。
Three observation methods were used to investigate the existing form and the behavior of rare earth during the sintering process of high activity mischmetal (RE, with lanthanum and cerium) doped WC-8%Co-0.048%RE(mass fraction) alloy with low carbon-containing level by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS), considering the fact that the addition amount of rare earth in the alloy is very minute. The directional migration process and mechanism of cerium were discussed. First, the sinter skin (surface) is observed. It is shown that there exists a dispersedly distributed cerium containing oxide on the sinter skin, and lanthanum in these cerium enrichment positions is very minute. Secondly, the polished section is observed, and lanthanum containing phase/micro-zone in the alloy is identified. Finally, based on the fact that the fracture of cemented carbide is resulted from the heterogeneous phase or other defects within the microstructure, the fracture surface is observed and cerium containing phase/micro-zone in the fracture source approximately 260 μm from the surface is identified. These combined observations reveal adequately the fact that lanthanum and cerium get separated and cerium predominantly migrates towards the surface during the sintering process.