Spark Plasma Sintering of Soft Magnetic Fe-Si-B-P-Cu Nanocrystalline Alloy in the Form of Magnetic Cores

Flakes of Fe84.3Si4B8P3Cu0.7 amorphous alloy ribbons with low glass forming ability were consolidated into bulk nanocrystalline specimens (magnetic core shape) with 12 mm in diameter and 2-5 mm 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 similar to 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 similar to 1.5-1.68 T, coercivity similar to 41-120 Am-1), and can be useful for high magnetic flux density and high frequency applications. [doi:10.2320/matertrans.M2011233]