| 摘要 |
PURPOSE:To contrive improvement in magnetic characteristics of the titled magnet by a method wherein, when an Nd-Fe-B alloy having Nd2Fe14B as the main growing phase is manufactured by performing melting and casting processes, the cooling process to be performed after casting is conducted at the cooling rate of 30 deg.C/min or above. CONSTITUTION:Six kinds of ingots, having the alloy composition of Nd of 34wt%, B of 1wt%, and Fe of the remaining wt%, are melted by performing a high frequency heating treatment on the Nd, Fe and B of the purity of 95wt% or above in an argon atmosphere, and after casting, they are cooled to 200 deg.C through six cooling stages of 1, 3, 10, 30, 100 and 30 deg.C/min. Then, after said ingots are coarsely pulverized, they are wet-grinded to approximately 4mum using a ball mill, and the obtained powder is molded by applying the pressure of 1.0ton/cm<2> in the magnetic field of 10KOe. This green compact is sintered at the temperature range of 1,050-1,100 deg.C for 2hr in the atmosphere of Ar, and after it is slowly cooled at the cooling rate of 100 deg.C/hr, the sintered body is heated at 550 deg.C for 1hr and then it is cooled quickly. As a result, an improvement in characteristics of the magnet can be recognized at the cooling rate of 10 deg.C/min or above after the melting and casting of the alloy, and the improvement in characteristics of the alloy can also be observed conspicuously at the cooling rate of 30 deg.C/min or above. |
