Growth of boride layers on the 13% Cr steel surface in a mixture of amorphous boron and KBF4

• Published in: Journal of materials science Vol. 42; no. 16; pp. 6614 - 6627
• Main Author: DYBKOV, V. I
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.08.2007; Springer Nature B.V
• Subjects: Abrasive wear; Borides; Boriding; Boron steels; Chromium steels; Cross-disciplinary physics: materials science; rheology; Differential equations; Exact sciences and technology; Materials science; Microhardness; Nonlinear equations; Other topics in materials science; Physics; Reaction kinetics; Wear resistance; Borides
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-007-1512-2

Two borides FeB and Fe2B were found to form as separate layers at the interface between a 13% Cr steel and boron at 850–950 °C and reaction times up to 12 h. The average chromium content is 8 at.% in the FeB layer and 9 at.% in the Fe2B layer. Both layers are characterized by a pronounced texture. The strongest reflections are {002} and {020} for the orthorhombic FeB phase and {002} for the tetragonal Fe2B phase. Diffusional growth kinetics of boride layers are close to parabolic and can alternatively be described by a system of two non-linear differential equations, producing a good fit to the experimental data. Annealing of a borided steel sample in the absence of boriding media results in disappearance of the FeB layer. Microhardness values are 17.9 ± 1.5 GPa for the FeB layer, 16.1 ± 0.9 for the Fe2B layer and 5.9 ± 0.3 GPa for the steel base. The abrasive wear resistance of the FeB layer is 25 times greater than that of the steel base. The Fe2B layer yields about a 15-fold increase in wear resistance of steel samples.