镧、铈在WC-Co合金中赋存状态的研究

Existing States of Lanthanum and Cerium in WC-Co Hardmetal

采用扫描电镜对高活性混合稀土掺杂的WC-8%Co-0.8%RE(RE:以La,Ce为主体的混合稀土)硬质合金的微观组织结构与合金烧结体表面进行了观察,采用元素面分布分析方法研究了合金中与合金烧结体表面La,Ce的结合状态。结果表明,合金中La,Ce处于原始结合状态,以细小第三相形式弥散分布于合金中;合金烧结体表面仅检测到呈不规则形状的含Ce氧化物的存在,La,Ce脱离了其原始结合状态,从而揭示了La,Ce结合状态的不稳定行为。通过考察掺杂前后合金Palmqvist断裂韧性的变化,对稀土相与WC硬质相、Co基固溶体粘结相之间的界面结合强度进行了间接评估。结果表明,合金中稀土相与合金中的其他两相之间具有较好的界面结合强度。

The microstructure and the sinter skin of high-activity mischmetal （RE, with La and Ce） doped WC-8% Co-0. 8% RE hardmetal were observed by scanning electron microscopy. The element surface distribution analysis was used in the study of the combining states of La and Ce both in the alloy and on the sinter skin. It was shown that in the alloy, a fine La and Ce containing phase was distributed dispersedly, and La and Ce were in their initial combining state.Nevertheless, on the sinter skin, only Ce containing oxide phase which was in an irregular shape was detected, and the initial combining state of La and Ce was broken, indicating an unstable La and Ce combining state. The good interface combining strengths of the La and Ce containing phase with the WC hard phase and the binder phase were revealed by comparing the Palmqvist fracture toughness of the hardmetal with and without RE.