N. E. Fenineche, M. Cherigui, P. C. Coddet, University of Technology Belfort-Montbeliard, Belfort Cedex, France
The development of electromagnetic devices exhibits a great tendency to be small in size and light in weight. This miniaturization needs excellent soft magnetic properties. Nanocrystalline structures offer a new opportunity for tailoring soft magnetic properties.
Nanocrystalline Fe based alloys combine the advantageous properties of various soft magnetic materials, i.e., the high saturation induction of Fe-based alloys, the high permeability and low magnetostriction of permalloys or amorphous Co-based alloys and the favourable high frequency behaviour of ferrites or amorphous metals. Nanocrystalline FeCuNbSiB alloys, also called Finemet exhibit particularly attractive magnetic properties such as high saturation magnetic induction, high permeability, and low core loss, simultaneously. Hence, these alloys are widely used for industrial applications and their magnetic softness has been theoretically explained.
An important issue concerning nanocrystalline materials is now to fabricate massive nanocrystalline parts ready to be used and several processing routes are under development. Particularly, nanocrystalline coatings thermally sprayed using milled powders has been recently successfully achieved for Ni and Fe based alloys. The major advantage of this processing route is its cost effectiveness which may rapidly lead to industrial applications.
In this context, HVOF thermal spraying was used to form nanocrystalline coatings using nanostructured powders produced by ball milling.
Microstructures and magnetic properties of FeSiBNbCu coatings have been characterized. Magnetic measurements show a soft magnetic character and a good stability after heat treatments.
Summary: An important issue concerning nanocrystalline materials is now to fabricate massive nanocrystalline parts ready to be used and several processing routes are under development. HVOF thermal spraying was used to form nanocrystalline coatings using nanostructured powders produced by ball milling.
Microstructures and magnetic properties of FeSiBNbCu coatings have been characterized. Magnetic measurements show a soft magnetic character and a good stability after heat treatments.
