# Applicability of a dilute quaternary model in interpreting the thermodynamic properties of the Fe-Ni-Ta-N system

Jayaganthan, R and Hajra, JP (1997) Applicability of a dilute quaternary model in interpreting the thermodynamic properties of the Fe-Ni-Ta-N system. In: Scripta Materialia, 37 (10). pp. 1539-1544.

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## Abstract

Interaction parameter formalism is considered to be important for representation of the excess thermo- dynamic properties of multi-component systems.- Wagner (1) proposed an interaction parameter for- malism to dilute multi- component systems through a Maclaurin infinite series expansion for the partial excess free ene:rgy. Several researchers (2-10) have extended this approach to concentrated solution. Since the data for higher order parameters are not readily available, the activity coefficients of solutes at infinite dilutions have so far been used in calculating the excess properties of solutions. It has cently been shown that truncation of the Maclaurin infinite series removes exactness of the expressions for the activity coefficients of solutes in multi-component systems (3,6,7). It may be mentioned that some of the authors have suggested (a) special relations between interaction parameters and (b) intro- duction of a constant compositional path toward the solution of the problem. To overcome these con- straints, the present authors (10) have deduced the partial functions of the ternary system from the Maclaurin infincite series that is expressed in terms of the integral excess function of the system. The infinite series is subjected to appropriate boundary conditions and each of the terms of the series correlated to the corresponding interaction coefficients of the solutes of the system. In the present article, the same method as adopted in our earlier article (10) has been used for deducing the partials the Quatenary System. The derivation of $ln\gamma_1$ $ln\gamma_2,$ $ln\gamma_3$ and $ln\gamma_4$, of the quaternary system involves extensive sumrnation of various infinite series pertaining to first order and quaternary parameters order to preserve thermodynamic consistency. Although the derivation and consistency of the partials are described elsewhere (12), a brief outline of the latter with an emphasis of their applicability to experimental data (11) of the Fe-Ni-Ta-N system in the temperature range of 1796- 983K presented.

Item Type: Journal Article Copyright of this article belongs to Elsevier. Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy) Anka Setty 23 Jun 2007 19 Sep 2010 04:35 http://eprints.iisc.ac.in/id/eprint/10124