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Keywords:

  • interatomic interactions;
  • magnetic impurity interactions;
  • short-range order;
  • diffuse scattering;
  • statistical thermodynamics

Within the scope of the self-consistent-field (SCF) and mean-SCF approximations, the Matsubara–Kanzaki–Krivoglaz lattice-statics method as well as the Krivoglaz–Clapp–Moss approach, the kinematic diffuse scattering intensities near the Bragg reflection caused by the atomic short-range order (taking into account the long-range magnetic order) in a (para)magnetic bulk face-centred cubic Ni–Fe alloy are investigated in detail. The reciprocal-space symmetry analysis of both the `direct' `electrochemical' and short-range `exchange' interactions as well as the long-range `indirect' `strain-induced' contribution to the Fourier components of interatomic `mixing' energies and the diffuse scattering intensity contributions near the `fundamental' Γ(000)-point is carried out. In the Γ-point vicinity, the rigorous symmetry regularities for all the energy and diffuse scattering intensity contributions are formulated. As revealed, the short-range order (SRO) diffuse scattering intensity behaves conditionally as inline image for inline image from all the reciprocal-space directions, which is in contrast to the conventional Huang diffuse scattering intensity conditionally definable as inline image for inline image. Special attention is paid to the analytic (i.e. azimuthal) and nonanalytic (i.e. first-kind-jump-discontinuous `radial') behaviours of the Fourier components of interatomic `mixing' energies or the SRO intensities near and at the Γ(000)-point.