| 摘要 |
PURPOSE:To obtain an R-Fe-B rare earth magnet whose coercive force is high and adhesive property of protective coating is high by limiting the sintering density within a specific range. CONSTITUTION:This is a sintered magnet whose sintering density rho is not less than 91% and less than 95% of true density, and the composition is of an R-Fe-B alloy. But, R is at least one among rare earth elements which include yttrium, and Fe can be partially replaced with transition metal such as Co, Ni, Mn, Zr, Nb, Ti, etc., and a part of B can be replaced with semimetal such as Si, P, Al, etc. For example, said R-Fe-B alloy magnet can be obtained by smashing an ingot, which is obtained by fusing and then cooling a material mixture, forming it, and next sintering it at a rather low specified temperature. In that case, the smashing is done so that the average grain diameter of particles being obtained may be 1-10mum, and the sintering temperature, though dependent on material and grain diameter, should be 950-1080 deg.C, preferably 1000-1050 deg.C. |
