Title: Growth kinetics of two-phase boride layers formed by boriding in molten salts on Cp-Ti substrate
Authors: Brahim Boumaali; Mourad Keddam; Sukru Taktak
Addresses: Laboratory of Materials Technology, Faculty of Mechanical Engineering and Process Engineering, USTHB, B.P. N°32, 16111, El-Alia, Bab-Ezzouar, Algiers, Algeria ' Laboratory of Materials Technology, Faculty of Mechanical Engineering and Process Engineering, USTHB, B.P. N°32, 16111, El-Alia, Bab-Ezzouar, Algiers, Algeria ' Department of Metallurgical and Materials Engineering, Faculty of Technology, Afyon Kocatepe University, ANS Campus, 03200 Afyonkarahisar, Turkey
Abstract: In this study, the pure titanium (Cp-Ti) was successfully borided in molten salts bath of (70 wt.% borax and 30 wt.% B4C) at the three temperatures (800,900 and 1,000°C) for time treatment ranging from 3 to 12 h. SEM observations showed the formation of the TiB2 layers followed by TiB whiskers penetrating into the matrix. The XRD studies also confirmed the presence of TiB2 top-layer and TiB whiskers sub-layer on the surfaces of hardened materials by boriding. The kinetics of formation of entire boride layer (TiB2 + TiB) was analysed. As a main result, the values of activation energies for boron diffusion in Cp-Ti were estimated by using two different approaches (classical parabolic growth law and integral method) as equal to 130.6 and 130.77 kJmol−1, respectively. These two values of energy were finally compared to the results available in the literature.
Keywords: boriding; Ti borides; kinetics; diffusion model; activation energy.
International Journal of Materials Engineering Innovation, 2018 Vol.9 No.3, pp.240 - 255
Received: 27 Nov 2017
Accepted: 13 Mar 2018
Published online: 09 Nov 2018 *