Spark plasma sintering of soft magnetic Fe-Si-B-P-Cu nanocrystalline alloy in the form of magnetic cores

Flakes of Fe _84.3Si ₄B ₈P ₃Cu _0.7 amorphous alloy ribbons with low glass forming ability were consolidated into bulk nanocrystalline specimens (magnetic core shape) with 12mm in diameter and 2-5mm in height by the spark plasma sintering (SPS) technique. The SPS technique, capable of rapid heating and cooling, enabled us to obtain a densely compacted bulk nanocrystalline material by maintaining the status of amorphous structure or nanocrystalline structure. As a result, high relative density ̃91.8-96.1% and nanocrystalline structure with average grain size below 41 nm were obtained. The Vickers hardness of the bulk nanocrystalline samples approaches to 1513, which is 2.0 and 3.2 times of the as-quenched amorphous ribbon and the fully annealed ingot, respectively. These sintered nanocrystalline materials exhibit good soft magnetic properties (saturation magnetic flux density ̃1.5-1.68 T, coercivity ̃41-120Am ^-1), and can be useful for high magnetic flux density and high frequency applications.