The miscibility gap in the FeBe system

The technique of atom probe field ion microscopy has been used to estimate the position of the low temperature miscibility gap in the iron-rich portion of the iron-beryllium system by direct measurement of the compositions of the phases.The morphology of the two phases produced by spinodal decomposition within this miscibility gap was determined to be a dislocated macrolattice of isolated cuboidal particles of the iron-rich 03B1 phase embedded in a matrix of the B2-ordered berylliumenriched FeBe phase.Atom probe measurements indicated that there was a significant variation in the compositions of the coexisting phases and the differences in the beryllium contents between the phases increased with aging time at 350 and 400 °C.Microsc.MicroanaL Microstruct.