RARE EARTH ALLOY POWDER OF COBALT 1-5 FOR SINTERED MAGNET

PURPOSE:To enhance the degree of sintering of compressed magnetic powder body and the coercive force of the sintered magnet by specifying an average grain diameter and specific surface area of the magnetic powder, followed by adding particulates with a particular grain size at more than 6wt.% in the magnetic powder. CONSTITUTION:Rare earth alloy powder of cobalt 1-5 produced by melting or reductive diffusion has an average grain diameter of 2-5mum and a specific surface area of at most 0.7m /g and contains particulates with a grain diameter of at least 20mum at 6wt.% or more. Here, a content of particulates having a grain diameter of at least 20mum is preferably 15wt.%. If the grain diameter of the alloy powder is less than 2mum, the alloy powder is liable to be oxidized thus degrading its degree of sintering, while the alloy powder with a grain diameter greater than 5mum, it lowers the degree of sintering and from such alloy powder it is difficult to produce sintered magnetic having a sufficient coercive force. Further, if the specific surface area of a particulate exceeds 0.7m /g, the alloy powder is liable to be oxidized, resulting in degradation of the degree of sintering of the alloy powder and also lowering of magnetization, with this, both the degree of compressed powder and the coercive force of sintered magnet can be enhanced.