Formation of bulk nanocrystalline and amorphous alloy with controllable microstructure and magnetic properties by plasma spray deposition

Nanostructured and amorphous materials exhibit unique and enhanced chemical, mechanical, and magnetic properties. The industrial applications of these materials rely on their successful consolidation into bulk body while preserving their structures. Nanostructured and amorphous coatings without grain growth can be formed by plasma spray deposition. In this case the microstructure of the bulk coating can be tuned from full amorphous state to composite with nanocrystalline particles in the amorphous matrix, and finally into nanostructured state accompanying with the magnetic properties changes. It was found that the desired magnetic properties of Co₅₈Ni₁₀Fe₅B₁₆Si₁₁ bulk alloy (zero magnetostriction, high initial and maximum magnetic permeability, etc.) can be achieved by formation of coating with certain amorphous/crystalline phase ratio. In the present work, the role of the plasma spray deposition regimes in the control of microstructure and magnetic property of the bulk coating, the mechanism for the nanocrystalline and amorphous structure formation, and the relation between the microstructure and magnetic properties are discussed.