Boriding of Fe and Fe-C, Fe-Cr and Fe-Ni alloys: boride-layer growth kinetics

摘要

Specimens of pure Fe and of Fe-0.8 wt% C, Fe-0.5 wt% Cr, Fe-4.0 wt% Cr, Fe-4.0 wt% Ni and Fe-10.0 wt% Ni alloys were bonded in commercially available "Ekabor 2" powder. In contrast to literature reports it was found that in all cases a surface-adjacent "FeB" sublayer was present on top of an "Fe_2B" sublayer in the compound layer. Layer-growth kinefics were analysed by measuring the extent of penetration of the "FeB" and "Fe_2B" sublayers as a function of boriding time and temperature in the range 1000-1250 K. Layer growth is dominated by B diffusion through "FeB/Fe_2B".