High Energy Density Magnetic Materials for Electronic Packaging

Permanent magnet materials are of growing interest to the electronics industry and to manufacture of electromechanical devices, where they constitute indispensable elements in many electronic apparatus, circuits, electric motors. The permanent magnets have a major influence on the size, efficiency, stability and the cost of these systems and devices. The development of the rare earth magnetic materials (starting with 70's) has influenced significant and positively the application of the permanent magnetic materials owing to their large energy product and increased volume efficiency. The further improvement of current magnetic materials relies on nanostructuring. An example of improving the performance of magnetic materials by nanostructuring is the magnetic nanocomposites, constituted by a hard magnetic phase and a soft magnetic phase. The adding of the soft magnetic phase to the hard phase in a suitable nanostructure improves the permanent magnet performances beyond that of the hard phase, due to the exchange interaction. The paper reviews the current hard magnetic materials prepared by powder metallurgy: NdFeB sintered and bonded magnets and presents the researches concerning the new generation of hard magnetic materials: Nd₂Fe₁₄B/alpha-Fe nanocomposites. A special attention is accorded to the binary Fe-Cu system. The paper presents also the results related to the preparation and complex characterization of the Fe-Cu composites