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The Application of X‐ray Diffuse Scattering to the Calculation of the FeAl Equilibrium Diagram
Author(s) -
Semenovskaya S. V.
Publication year - 1974
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220640134
Subject(s) - diagram , fourier transform , scattering , lattice (music) , spins , thermodynamics , physics , chemistry , condensed matter physics , atomic physics , quantum mechanics , mathematics , statistics , acoustics
Absolute intensity measurements of diffuse X‐ray scattering on single crystals of disordered equilibrium FeAl alloys are made at (000), (111), and (1/2,1/2,1/2) points of the reciprocal lattice of b.c.c crystals. These measurements give the opportunity of obtaining the three corresponding Fourier transforms of the interchange energies. According to Khachaturyan's theory these Fourier transforms are the energetic parameters which completely determine the thermodynamics of FeAl alloys in a self‐consistent field approximation. For the case of long‐range interactions each of the three parameters obtained includes all of the interchange energies. The contribution to the free energy of the exchange interactions of the set of the local spins (S o = 1) placed on Fe‐atoms was evaluated. This result and obtained experimental values of the three energetic parameters allowed to calculate the FeAl diagram. The calculated diagram is in a very good agreement with the most recent diagram by Swann, Duff, and Fisher obtained by an electron microscopic method (discrepancies with respect to absolute temperature and compositions are everywhere less than 11%) though “adopt” parameters are nowhere used to “tie” the calculated and observed diagram to each other. It is shown that the equilibrium diagram depends essentially on the magnetic contribution to the total free energy.