Analytical behavior of short-range order scattering of Cu-rich Cu-Mn near the Γ point

Small-angle neutron scattering with scattering vectors in the range of 0.01 to 0.17 reciprocal lattice units was measured for a single crystal of Cu-17.2 at.% Mn aged at 483 K. At large scattering vectors, a directional dependence of the scattering intensity is observed, with slightly higher values along <100> than along <110>. The difference in intensities continuously decreases with decreasing scattering vector. The present data contradict the results of a previous synchrotron radiation study where it was concluded that short-range order scattering is nonanalytical at the Γ point. The discrepancy is traced back to multiple Bragg scattering with high-energy x rays