Al-Ni-Co系磁石の低温処理におよぼすAlの影響

Abstract

In a previous paper it was found that the magnetic properties of Alnico type N.K.S.-1F permanent magnet showed anomaly at about 875°C, and the maximum energy product of magnet thus treated was the same as or better than that by the high temperature treatment. In this paper, the variation in the temperature of the low temperature treatment was measured with a series of magnet alloys containing various Al contents 6 to 10%. The experiments showed that the temperature of low temperature treatment increased with the Al content and the rate of variation was about 67.6°C per unit % of Al.At the same time the Curie points of these magnets were measured. The Curie points A2 were found to be almost constant except in the case of a high Al content, and A2 coincided with the optimum temperature of low temperature treatment TL in the standard composition of 8%Al at which the magnetic properties were most satisfactory, while it was lower than TL with a higher Al content and higher with a lower Al content. This suggests that the effect of the low temperature treatment is the most excellent as the difference of A2 and TL is the smallest.