非化学计量金属间化合物DO_3型Fe_3Al热力学性质  

Thermodynamic Properties of Nonstoichiometric Intermetallic Compounds Fe_3Al with DO_3 Structure

作　　者：黄永章[1] 袁文霞[2] 朱鸿民[1] 乔芝郁[1] 

机构地区：[1]北京科技大学冶金与生态工程学院 [2]北京科技大学应用科学学院,北京100083

出　　处：《物理化学学报》2005年第3期273-277,共5页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(50304002);国家教委博士点基金(20020008017);教育部留学归国基金(19990611950)资助项目~~

摘　　要：用以CaF2单晶为固体电解质的电池电动势(EMF)法测定了720～850K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ΔG珡Al、ΔH珡Al、ΔS珔Al,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750K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.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 ,, 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).

关 键 词：电池电动势法 CAF2 FE3AL 活度 热力学因子 

分 类 号：TM911[电气工程—电力电子与电力传动]