| 摘要 |
PURPOSE:To offer low-cost and high-performance alloy powder for a magnet, composed of a rare-earth element, iron and boron, which can be used for sintering and for resin bonding by a method wherein the alloy powder which has been finely pulverized by a gas atomizing method are classified and they are then annealed while their heat-treatment condition is changed according to the range of their particle size. CONSTITUTION:Alloy powder for a magnet by this invention are composed of 8-30 atomic % of R (R contains at least more than one rare-earth element including Y), 2-28 atomic % of B, less than 50 atomic % of Co and less than 16 atomic % of Al; their remaining part is composed of Fe. Because the alloy powder is produced by using a gas atomizing method, their particle sizes are distributed widely. The powder of a big particle size whose particles are constituted by a crystal phase and where an amorphous phase is hardly detected are annealed at a high temperature and for long hours such as at 1000 deg.C and for 24 hours so that their coercive force can be increased. The powder of a small particle size which contains the amporphous phase are annealed at a low temperature and for short hours such as at 700 deg.C and for 10 minutes so that their high coercive force can be obtained. |
