L1_2Ni_3Ga和DO_3Fe_3Al非化学计量金属间化合物的活度、热力学因子和互扩散系数

Activity,thermodynamic factor in chemical diffusion and interdiffusion coefficient in the L1_2-Ni_3Ga and DO_3-Fe_3Al non-stoichiometric intermetallic compounds

基于L12Ni3Ga和DO3Fe3Al非化学计量金属间化合物中Ga和Al的活度,利用Φ=xi·lnaixi分别计算了不同温度时L12Ni3Ga和DO3Fe3Al相中扩散的热力学因子Φ.计算表明,在化学计量比处附近L12Ni3Ga和DO3Fe3Al相中扩散的热力学因子Φ趋于最大值。根据DarkenManning公式D=(xBDA+xADB)·Φ·S,由扩散的热力学因子Φ及自扩散系数分别计算了1123,1223和1261K下L12Ni3Ga和823K下DO3Fe3Al非化学计量金属间化合物的互扩散系数D.

The thermodynamic factors in diffusion,Φ=x_i·ln a_ix_i in the L1_2-Ni_3Ga and DO_3-Fe_3Al non-stoichiometric phase were derived from the experimentally measured activities of Ga and Al, respectively. The results show that the thermodynamic factors in diffusion in the L1_2-Ni_3Ga and DO_3-Fe_3Al phases exhibit the maximum near the stoichiometric composition with the variation of composition over the phase region. By applying the Darken-Manning equation ~=(x_BD*_A+x_AD*_B) ·Φ·S, the interdiffusion coefficients at different temperatures respectively in the L1_2-Ni_3Ga and DO_3-Fe_3Al non-stoichiometric phase were calculated using thermodynamic factor in chemical diffusion Φ and tracer self-diffusion coefficients ~D*_A(A:Ni or Fe) and D*_B (B:Ga or Al)reported in the literature.