A Diffusion Model for the Fe_{2}B Layers Formed on a Ductile Cast Iron

In this work, a diffusion model was applied to estimate the boron diffusion coefficients in the $Fe_{2}B$ layers on the ASTM A-536 ductile iron in the temperature range 1173-1273 K by the powder-pack boriding. The mass balance equation at the ($Fe_{2}B$/substrate) interface was formulated considering the effect of boride incubation times. As a result, the value of activation energy for boron diffusion in the ductile iron was estimated and compared with the literature. To verify the validity of the present model, the experimental $Fe_{2}B$ layer thickness obtained at 1173 K for 10 h was compared to the predicted value. A good concordance was observed between the predicted value of $Fe_{2}B$ layer thickness and the experimental data.