AGING OF GLASSY TRANSFORMER CORE ALLOYS AND THE ACTIVATION-ENERGY SPECTRUM MODEL

Aging was characterized through measurement of core loss in small toro idal cores of metallic glass ribbons at various temperatures. The incr ease in core loss follows log-time kinetics. It is shown that the acti vation energy spectrum model fits the data very well. Estimates of tim e for serious degradation of the properties of a commercial Fe-B-Si gl ass at device temperatures will be provided. In contrast to silicon st eels, the addition of carbon to Fe-B-Si glasses is shown to have no ad verse effects on aging behavior. The effects of surface crystallinity on the aging behavior are also discussed.