(1. 北京科技大學 材料科學與工程學院，北京 100083；
2. 重慶材料研究院 國家儀表功能材料研究中心，重慶 400700)
摘 要: 通過真空條件下Co-Fe-Sb三元體系1 073 K等溫截面測定、Co-Fe-Sb三元體系凝聚態(tài)的熱力學優(yōu)化評估和氣相組分的熱力學數(shù)據(jù)計算，分析氣相壓力對該體系中二元和三元體系的相平衡和相穩(wěn)定性的影響。結(jié)果表明： 隨著氣相壓力減小到一定程度，Co-Sb、Co-Fe、Fe-Sb和Co-Fe-Sb體系中的固相化合物相開始發(fā)生揮發(fā)分解，出現(xiàn)氣−液−固三相平衡區(qū)，計算所得溫度—壓力曲線圖表明每種化合物相都存在一個理論的壓力極小值，并對應一個溫度，在此壓力之上或溫度以下，不發(fā)生化合物由固相轉(zhuǎn)變成氣相的分解，凝聚態(tài)相保持與常壓下基本相同的相平衡關(guān)系。計算結(jié)果從熱力學上很好地解釋了含Sb熱電材料在試驗研究和材料制備過程中存在的問題，對制備該化合物的工藝設計具有很好的參考作用。
關(guān)鍵字: Co-Fe-Sb三元體系；方鈷礦(CoSb3)；氣相壓力；相平衡；相穩(wěn)定性
（1. School of Materials Science and Engineering, University of Science and Technology Beijing,
Beijing 100083, China;
2. National Instrument Engineering Technology Research Center for Functional Materials,
Chongqing Materials Research Institute, Chongqing 400700, China）
Abstract:By means of the determination of the isothermal-section at 1 073 K of the Co-Fe-Sb ternary system in vacuum condition，the assessed thermodynamic parameters of the condensed phases and those of the constituent gas-phase species of the Co-Fe-Sb ternary system, the influences of the gas-phase pressure on the phase equilibria and the phase stability of the binary and ternary systems were calculated and analyzed. The results show that the compounds of the Co-Sb, Co-Fe, Fe-Sb and Co-Fe-Sb systems start to pyrolyze when the gas-phase pressure decreases to a certain degree, and the gas-liquid-solid three-phase equilibrium zones appear. The calculated pressure—temperature curves show that each compound has a minimum pressure value corresponding to a temperature for its decomposition or pyrolysis. Above the minimum pressure or below the temperature, the compound phase cannot decompose from solid phase to gas phase with temperature change and can keep the same phase relations as those at the normal pressure. The calculated results can thermodynamically explain the problems appearing in the experimental investigations and the preparation processes of the Sb containing thermoelectric materials, and can be helpful for reference to the process design for the preparation of the compound.
Key words: Co-Fe-Sb ternary system; skutterudite (CoSb3); gas phase pressure; phase equilibrium; phase stability
