A Semi-Empirical Parameterization of Interatomic Interactions Based on the Statisticaf-Thermodynamic Analysis of the Data on Radiation Diffraction and Phase Equilibria in F.C.C.-Ni-Fe Alloys

摘要

Using both the statistical-thermodynamics methods within the scope of the self-consistent field approximation and the diffraction data on coherent (or diffuse) scattering of X-rays (or thermal neutrons) from (dis)ordered fee,.-Ni-Fe alloys of various compositions, the estimation of intera-tomic interactions (including their magnetic contribution) and their temperature-concentration dependences were obtained. Based on the static concentration-wave representation, the expressions for configuration free energies of Lh-NisFe-type permalloy, Llo-NiFe-type elinvar and Ll2-Fe3Ni-type invar were analyzed, considering explicit expressions for configuration entropies of atomic and magnetic subsystems with their configuration internal energies Phase diagram of a system at issue was plotted within the field of the presence of f,c c -Ni-Fe alloys; their phase boundaries, equilibrium (static) properties near critical points (order parameter, etc.), and possible microstructures developed by composition-controlled magnetic transitions and/or order-disorder constant-composition solid-solid phase transformations were discussed. The obtained results were compared with available experimental data.