ATOMIC SHORT-RANGE ORDER IN CU-17 AT-PERCENT MN

The elastic diffuse neutron scattering from a Cu-17.2 at% Mn single cr ystal aged at 483 K to produce an equilibrium state of atomic short-ra nge order is measured at room temperature in a minimum separation volu me of reciprocal space. Warren-Cowley short-range order parameters and coefficients of linear static displacement scattering are determined by least-squares fitting. Effective pair potentials obtained from the short-range order parameters by applying the inverse Monte-Carlo metho d are used to calculate the diffuse antiphase boundary energy gamma(AP B). For copper-base alloys the concentration dependence of gamma(APB) is one of the suggested reasons for the transition of wavy to planar s lip. Based on the values of gamma(APB), the concentration ranges for t he transition in Cu-Mn, Cu-Al, and Cu-Zn may be understood.