High temperature magnetic properties of 49%Co-2%V-Fe alloy

Direct current hysteresis loops of 49%Co-2%V-Fe alloy have been measured at temperatures up to 800 degrees C. Two phase structure is evident in the B-H loops between 580 and 730 degrees C. This alloy cannot be reliably operated above 580 degrees C. The second magnetic phase is believed to result from the nucleation and growth of disordered a phase in the ordered alpha' phase matrix. Magnetic properties (measured as B at H=2.5 and 10 Oe) degrade with time during aging at 450 degrees C, but approach stable values after about 1000 h, which provides the possibility for long-term high temperature (e.g., 450 degrees C) operation if the degraded properties are still acceptable for the application. The coercive field remains unchanged while the permeability decreases irreversibly during aging. The irreversible magnetic property changes that occur during aging at 450 degrees C are most likely caused by an increase in the long range order parameter. (C) 1996 American Institute of Physics.