Title: Diffusion model and characterisation of Fe₂B layers on AISI 1018 steel

Authors: Martín Ortiz-Domínguez; Jorge Zuno-Silva; Mourad Keddam; Omar Damián-Mejía; Milton Elias-Espinosa

Addresses: Universidad Autónoma del Estado de Hidalgo, Campus Sahagún, Carretera Cd. Sahagún-Otumba s/n, Hidalgo, México ' Universidad Autónoma del Estado de Hidalgo, Campus Sahagún, Carretera Cd. Sahagún-Otumba s/n, Hidalgo, México ' Laboratoire de Technologie des Matériaux, Département de Sciences des Matériaux, Faculté de Génie Mécanique et Génie des Procédés, USTHB, B.P. No. 32, 16111 El-Alia, Bab-Ezzouar, Algiers, Algeria ' Instituto de Investigación en Materiales, Universidad Nacional Autónoma de México-UNAM, Circuito Exterior, s/n Ciudad Universitaria, Coyoacán, CP 04510, México ' Instituto Tecnológico y de Estudios Superiores de Monterrey-ITESM, Campus Santa Fe, Av. Carlos Lazo No. 100, Del. Álvaro Obregón, CP. 01389, México

Abstract: An approach was suggested to study the kinetics of formation of Fe₂B layers grown at the surface of AISI 1018 steel by the pack-boriding process. The kinetic model considered the principle of mass conservation at the (Fe₂B/substrate) interface to evaluate the boron diffusion coefficient of Fe₂B in the temperature range of 1,123-1,273 K. Validation of the model was made by comparing the experimental Fe₂B layer thickness with the predicted value for the borided sample at 1,253 K during 5 h. In addition, the generated boride layers were analysed by optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis. Finally, a contour diagram describing the evolution of Fe₂B layer thickness as a function of treatment time and temperature was also proposed. Finally, the boron activation energy for AISI 1018 steel was estimated as 159.3 kJ mol⁻¹ basing on our experimental results.

Keywords: boriding; iron boride; incubation time; diffusion models; growth kinetics; activation energy; modelling; AISI 1018 steel; kinetic modelling; layer thickness; treatment time; temperature.

DOI: 10.1504/IJSURFSE.2015.070808

International Journal of Surface Science and Engineering, 2015 Vol.9 No.4, pp.281 - 297

Received: 11 Feb 2014
Accepted: 11 Apr 2014
Published online: 28 Jul 2015 *

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