放電プラズマ法(SPS)を用いたFe-Cr-Co焼結磁石の微細組織と磁気特性 Microstructures and Magnetic Properties of Sintered Fe-Cr-Co Type Magnets using Spark Plasma Sintering
The objective of this study was to investigate differences in microstructures and magnetic properties on the Fe-Cr-Co type magnets due to the processing variables, such as initial powders and sintering temperatures of spark plasma sintering (SPS). The Fe-Cr-Co powders with a grain under 80μm were prepared by spray conversion process. The sintered Fe-Cr-Co compacts achieve high relative densities (about 98%) by process conditions with 39 MPa at 1223 K for 7 minutes using spark plasma sintering. The stable high magnetic hardening of the compacts was performed after heat treating with the miscibility gap, producing modulated structures consisting of two phases an iron-rich phase (a<SUB>1</SUB>) and chromium-rich phase (a<SUB>2</SUB>). According to above results, The SPS is recognized to be superior on sintering conditions (in shorter time and at lower temperature) to the conventional furnaces. So that Spark plasma sintering has a high possibility of being applied as a method of sintering Fe-Cr-Co magnet in the near future.
粉体および粉末冶金 51(7), 554-558, 2004-07-15