R-T-B BASED RARE EARTH MAGNET POWDER, METHOD OF MANUFACTURING THE SAME, AND BOND MAGNET

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PROBLEM TO BE SOLVED : To provide a method of obtaining magnet powder having high squareness and reconciling excellent residual magnetic flux density and coercive force by controlling a processing condition in an HD process in an HDDR process and suppressing a decline of residual magnetic flux density of a small particle. SOLUTION : In this method of manufacturing the R-T-B based rare earth magnet powder by the HDDR process, the composition of a raw material alloy has an R amount of 12.5 at.% or more and 14.3 at.% or less, a B amount is 4.5 at.% or more and 7.5 at.% or less, and a Co amount of 10 at.% or less. A first stage HD process in which after the temperature of raw material alloy powder is raised to a temperature range of 770°C or higher and 820°C or lower in an inert atmosphere or a vacuum atmosphere, the atmosphere is changed to a hydrogen containing gas atmosphere, and the raw material alloy powder is held in the above mentioned temperature range is carried out, and a second stage HD process in which the temperature of the raw material alloy powder is again raised to a temperature range of 830°C or higher and 870°C or lower and the raw material alloy powder is held in the hydrogen containing gas atmosphere is carried out. COPYRIGHT : (C)2014, JPO&INPIT