物理化学学报 >> 2005, Vol. 21 >> Issue (03): 273-277.doi: 10.3866/PKU.WHXB20050309

研究论文 上一篇    下一篇

非化学计量金属间化合物DO3型Fe3Al热力学性质

黄永章; 袁文霞; 朱鸿民; 乔芝郁   

  1. 北京科技大学冶金与生态工程学院; 北京科技大学应用科学学院,北京 100083
  • 收稿日期:2004-07-21 修回日期:2004-10-11 发布日期:2005-03-15
  • 通讯作者: 乔芝郁 E-mail:zyqiao@metall.ustb.edu.cn

Thermodynamic Properties of Nonstoichiometric Intermetallic Compounds Fe3Al with DO3 Structure

HUANG Yong-Zhang; YUAN Wen-Xia; ZHU Hong-Min; QIAO Zhi-Yu   

  1. School of Metallurgical and Ecological Engineering, University of Science & Technology Beijing; School of Applied Science, University of Science & Technology Beijing, Beijing 100083
  • Received:2004-07-21 Revised:2004-10-11 Published:2005-03-15
  • Contact: QIAO Zhi-Yu E-mail:zyqiao@metall.ustb.edu.cn

摘要: 用以CaF2单晶为固体电解质的电池电动势(EMF)法测定了720~850 K温度区间内(-)Pt|Ir|Al0.85Sn0.15,Na3AlF6|CaF2|AlxFe1-x(x=0.23~0.33),Na3AlF6|Ir|Pt(+)电池电动势,通过DO3型Fe3Al的粉末化以及选用富Al合金Al0.85Sn0.15作为参比电极,使电池反应较快地达到热力学平衡,EMF测量前后工作电极的X射线衍射分析证明没有化学变化发生.计算了DO3型Fe3Al非化学计量金属间化合物均相范围内组元Al的活度及Al的偏摩尔热力学函数ΔGAl、ΔHAl、ΔSAl ,基于Gibbs-Duhem方程计算了DO3型Fe3Al中另一组元Fe的活度和偏摩尔Gibbs自由能.计算了750 K时DO3型Fe3Al相中Al的扩散热力学因子,在化学计量比成分(xAl=0.25)附近Fe3Al相中Al扩散的热力学因子达到最大值.

关键词: 电池电动势法, CaF2, Fe3Al, 活度, 热力学因子

Abstract: The electromotive force(EMF) values of the cell (-)Pt|Ir|Al0.85Sn0.15, Na3AlF6|CaF2|AlxFe1-x(x=0.23~0.33), Na3AlF6|Ir|Pt (+) were measured between 720 K and 847 K using solid galvanic cells with a single-crystal CaF2 electrolyte. For attaining quick thermodynamic equilibrium of the cell, Al0.85Sn0.15 alloy was used as the reference electrode and DO3-Fe3Al was powdered. It was confirmed that there was no chemical transformation in the working electrode by X-ray diffraction experiments before and after EMF measurement. The Al activities in Fe3Al with DO3-ordered nonstoichiometric intermetallic compounds were derived. The partial molar thermodynamic functions ΔGAl、ΔHAl、ΔSAl of Al were calculated. The activities and partial molar Gibbs energies of Fe in the Fe-Al alloys were derived by Gibbs-Duhem equation. The thermodynamic factor in diffusion of aluminum in the Fe3Al phase at 750 K was calculated, and showed a maximum at a composition near the stoichiometric proportion (xAl=0.25).

Key words: Electromotive force (EMF), CaF2, Fe3Al, Activity, Thermodynamic factor