THE AGING OF PERMANENT MAGNET ALLOYS AT TEMPERATURES OF 550-700 DEGREES C,

Abstract : The influence of structural aging in the range 550 to 700 degrees centigrade of YuNDK35T5 and YuNDK24 (All Union State Standard 9576 60) type alloys on their magnetic properties is examined. For the YuNDK35T5 type alloy, the change in structure as a result of structural aging in the given temperature range over a long period of time (on the order of 1000 hours) is studied. The difference in the change of magnetic induction between alloy types YuNDK35T5 and alloys YuNDK24 and YuNDK25BA is insignificant. In all YuNDK35T5 type alloys, a rapid decrease in magnetic induction begins at temperatures higher than 600 degrees centigrade; in YuNDK24 type alloys at 600 degrees centigrade, magnetic induction continuously falls. Structural transformations at 550 degrees centigrade in all alloys and in YuNDK35T5 type alloys at 600 degrees centigrade may lead to an increase in magnetic induction during repeated magnetization to saturation after holding. However, an increase in induction as a result of general aging of magnets (without repeated magnetization) ordinarily does not exceed 1 percent, even in those cases where repeated magnetization gives an increase in induction greater than 10 percent (pure structural aging). (Author)