Reactions and phase relations in the systems Fe-Ni-B and Fe-Co-B

Displacement reactions have been studied in the Fe-Ni-B system at 925°C and in the Fe-Co-B system at 900°C, together with the phase relations existing in these systems at the same temperatures. Although the isothermal crosssections show a clear resemblance, the morphology ofthe reaction layers in the Ni/Fe2B and Co/Fe2B diffusion couples was different. It is shown that the reaction layer morphology is in line with thermodynamic deductions from the slopes of the conodes in the phase diagrams.