FeNb and FeSi thermal spraying coatings: microstructure and first principle calculations

Abstract

The development of amorphous and nanocrystalline materials has attracted significant interest in the field of new materials design. Indeed, the magnetic, chemical and mechanical properties of materials are largely enhanced when the size of crystallites becomes nanometric. In addition, the absence of crystal structure implicates a macroscopic behavior fairly different from that of corresponding to the polycrystalline state, especially, mechanical and magnetic properties. In this work, HVOF and APS thermal spraying were used to produce silicon–iron and niobium–iron alloys coatings. Adjusting the spraying conditions, amorphous coatings were obtained from the FeNb powder. However, for the silicon–iron powder, crystalline deposits were produced in all cases. Boron additives were used to improve the aptitude of the silicon–iron alloy to form an amorphous phase. In this perspective, first principle calculations were elaborated to investigate the electronic structure of crystalline FeNb and Fe 3Si. It was shown that the introduction of boron impurities into the alloy matrix lead to the lowering of the structural stability, and made its electronic density of state (DOS) more comparable to the corresponding niobium–iron structure.