Abstract
A simplified derivation of an equation equivalent to that of Sauer and Freise is presented by using the integral expressions of diffusion fluxes. Thus it is clarified that Balluffi’s equation may be brought to completion by supplementing it by the generalized Matano’s equation which describes the location of the original interface when volume changes occur, and that eliminatation of the coordinate of the original interface in Balluffi’s equation leads to Sauer and Freise’s equation.
It is also shown that if one describes the interdiffusion phenomena by the total molefixed reference frame, all the equations not only become simple but also are isomorphic with those described by the ordinary laboratory-fixed reference frame with no volume change.
It is particulary emphasized that the total mole-fixed reference frame would be most adequate for the description of the interdiffusion phenomena accompanying volume changes. The Matano interfaces are also discussed in some detail.
