Formation and characterization of boride coatings thermochemically grown on the Fe64Ni36 alloy

Abstract

Boride coatings were grown on Armco iron and Fe 64 Ni 36 alloy at 850 • C for 20 min and 1 h, using a high boron potential powder constituted by KBF 4 -activated amorphous boron. The coatings were characterized by X-ray diffraction, Mössbauer spectroscopy and metallographic techniques. The use of high boron potential media allows iron borides to form with high Ni contents because of a considerable reduction of the selective reactivity of boron towards Fe and Ni. As a consequence of the isomorphism between Fe 2 B and Ni 2 B and between FeB and NiB, the high amounts of Ni in iron borides do not significantly modify the XRD patterns, while they give rise to remarkable variations in the hyperfine parameters.