Study of solidification pathway of a MoSiBTiC alloy by optical thermal analysis and in-situ observation with electromagnetic levitation
Study of solidification pathway of a MoSiBTiC alloy by optical thermal analysis and in-situ observation with electromagnetic levitation
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DOI：
10.1038/s41598-019-50945-z
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发表时间：
2019-10-21
影响因子：
4.6
通讯作者：
Yoshimi, Kyosuke
中科院分区：
文献类型：
--
作者：
Fukuyama, Hiroyuki;Sawada, Ryogo;Yoshimi, Kyosuke
MoSiBTiC合金是下一代超高温材料的有希望的候选者。然而，这些合金的相图一直是未知的。我们开发了一种基于黑体辐射的超高温热分析仪，可用于分析合金的熔化和凝固67.5Mo-5Si-10B-8.75Ti-8.75 C（mol%）。此外，还利用电磁悬浮技术对合金的凝固过程和显微组织进行了原位观察。在此基础上，提出了以下凝固途径：Mo固溶体（Mo-ss）在1955 ℃（2228 K）开始从液态结晶出作为主相，随后在1900 ℃（2173 K）开始发生（Mo-ss+TiC）共晶反应。硼化钼（Mo 2B）相在共晶反应后从液体中沉淀;然而，随着凝固的进行，Mo 2B相可以与剩余的液体反应以形成Moss和Mo 5SiB 2（T-2）。此外，T-2也作为单相从液体中沉淀。剩余的液体在1880 ℃（2153 K）达到（Mo-ss+T-2+TiC）三元共晶点，并且（Mo-ss+T-2+ Mo 2C）共晶反应最终在1720 ℃（1993 K）发生。这完成了MoSiBTiC合金的固化。
MoSiBTiC alloys are promising candidates for next-generation ultrahigh-temperature materials. However, the phase diagram of these alloys has been unknown. We have developed an ultrahigh-temperature thermal analyser based on blackbody radiation that can be used to analyse the melting and solidification of the alloy 67.5Mo-5Si-10B-8.75Ti-8.75 C (mol%). Furthermore, electromagnetic levitation (EML) was used for in-situ observation of solidification and microstructural study of the alloy. On the basis of the results, the following solidification pathway is proposed: Mo solid solution (Mo-ss) begins to crystallize out as a primary phase at 1955 degrees C (2228 K) from a liquid state, which is followed by a (Mo-ss+TiC) eutectic reaction starting at 1900 degrees C (2173 K). Molybdenum boride (Mo2B) phase precipitates from the liquid after the eutectic reaction; however, the Mo2B phase may react with the remaining liquid to form Moss and Mo5SiB2 (T-2) as solidification proceeds. In addition, T-2 also precipitates as a single phase from the liquid. The remaining liquid reaches the (Mo-ss+T-2+TiC) ternary eutectic point at 1880 degrees C (2153 K), and the (Mo-ss+T-2+Mo2C) eutectic reaction finally occurs at 1720 degrees C (1993 K). This completes the solidification of the MoSiBTiC alloy.