The distribution of boron in a rapidly solidified Ni-24at%Al alloy containing 0.24at%B was investigated by atom probe field-ion microscopy. Boron was found to segregate to both antiphase and grain boundaries. Field-ion micrographs revealed that some of the antiphase boundaries and most of the grain boundaries were decorated with bright spots identified by single atom analysis as boron atoms. A 0.4 to 1.2nm thick boron-enriched phase was observed on most of the grain boundaries. The distribution of this phase was not uniform either along a boundary or from boundary to boundary. The degree of long-range order as measured by the atom probe was greater than 0.97. This state of order continued to the interface between the matrix and grain boundary phase.

Atom Probe Analysis of Grain Boundaries in Rapidly-Solidified Ni3Al. Horton, J.A., Miller, M.K.: Acta Metallurgica, 1987, 35[1], 133-41