KINETICS OF SHORT-RANGE AND LONG-RANGE B2 ORDERING IN FECO

Short-range and long-range-order parameters were measured by Mossbauer spectrometry and x-ray diffractometry during the disorder --> B2 order transformation in equiatomic FeCo. The change from a homogeneous mode of ordering at high temperatures to a heterogeneous mode of ordering at low temperatures was confirmed. By comparing parametric plots of the Fe-57 hyperfine magnetic field versus long-range-order parameter for ordering in these two modes, an early independent relaxation of the short-range order was found in the kinetic path for homogeneous ordering. This relaxation was in reasonable agreement with estimates based on statistical kinetic theory.