Seiichiro Watanabe1, Yoshio Kamata1 and Shinya Chikamatsu1
1Japan Special Steel Co. Ltd., Tokyo
For Alnico magnet alloys containing Ti, especially Alnico 7 and Alnico 8 containing 5%Ti, it has been extremely difficult to columnize or coarsen the crystals owing to the reciprocal action between Al and Ti. In view of the fact that Al and Ti are used as an excellent deoxidizer or denitrizer and their gases as fixers in steel, making, the authors considered the neccessity of investigating the effects of N2 and O2 gases which are presumably generated ouring the melting of Alnico magnet alloys containing a large quantity of these two elements. In effect, it was confirmed that the content of N2 gas in other Alnico magnet alloys increased with an increase of the Ti content. It seems that these gases act on Al and Ti, and in the presence of Al, Ti can easily form compounds with these gases; the compounds induces a fine crystallization of Ti containing Alnico magnet alloys. An attempt was made to eliminate the influence of these gases constituently and succeeded in columnizing and coarsening the crystals of the abovementioned magnet alloys by a single or combined addition of one or more elements, not only S but also some elements coherent to S.
The amount of N2 and O2 gases decreased and the columnar crystals became longer as the S content increased.
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