Sm(Co, Fe, Cu)7型磁石合金の焼結および磁気特性に及ぼす粉末粒度の影響

概要

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Using three different kinds of Sm(Co, Fe, Cu)7 powder compacts whose particle diameters were 2.3, 4.1 and 6.0 μm, the effect of particle size on the sintering characteristics and the magnetic properties was investigated mainly by means of dilatometric method and EPMA. The results obtained are as follows: (1) The sinterd density of the Sm(Co, Fe, Cu)7 powder compacts increased with decreasing diameter of powder, and the maximum value was obtained at 2.3 μm in any sitering temperature from 1180°C to 1240°C, while the maximum energy product (BH)max was maximum at 4.1 μm. (2) In the higher sintering temperature range than 1240°C, the liquid phase sintering was observed in all specimens above mentioned, where the amount of liquid increased with increasing diameter of particle. (3) The oxygen concentrations of the sintered Sm(Co, Fe, Cu)7 compacts were determined to be 900 ppm, for 6.0 μm, 1200 ppm for 4.1 μm and 2800 ppm for 2.3 μm specimen. These high values of oxygen concentration are due to the strong affinity of samarium for oxygen, and the above mentioned results have been confirmed to be deeply connected with compositional shift of Sm(Co, Fe, Cu)7 alloy by oxidation.
社団法人粉体粉末冶金協会の論文