The B-rich side of the B-C phase diagram

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• 作者：Peter F. Rogl ; Jan V艡e拧钮谩l ; Takaho Tanaka ; Satoshi Takenouchi
• 关键词：Beta boron ; (ß ; B) peritectic melting ; Floating zone method ; B&ndash ; C phase diagram modeling ; Ternary metal&ndash ; boron&ndash ; carbon systems
• 刊名：Calphad
• 出版年：March, 2014
• 年：2014
• 卷：44
• 期：Complete
• 页码：3-9
• 全文大小：2939 K

文摘

The melting behavior of 脽-boron at the boron-rich side of the B-C binary phase diagram is a long standing question whether eutectic or peritectic. Floating zone experiments have been employed to determine the melting type on a series of C-containing feed-rods prepared by powder metallurgy and sinter techniques. Melting point data as a function of carbon-content clearly yielded a peritectic reaction isotherm: L+B_4+未C=(脽B). The partition coefficient of carbon is ~2.6. The experimental melting point data were used to improve the existing thermodynamic modeling of the system B-C. Relative to the thermodynamically accepted melting point of pure 脽B (T_M=2075 掳C), the calculated reaction isotherm is determined at 2100.6 掳C, a peritectic point at 0.75 at% C and a maximum solid solubility of 1.43 at% C in (脽B) at reaction temperature. With the new melting data the refractory system Hf-B-C has been recalculated and the liquidus surface is presented. The influence of the melting behavior of (脽B) on the phase reactions in the B-rich corner of M-B-C diagrams will be discussed and demonstrated in case of the Ti-B-C system.