Magnetomechanical Coupling and Ultrasound Velocities In Fe79si12b9 Metallic-glass After Annealing In Vacuum Near the Crystallization Temperature

The influence of annealing in vacuum at temperatures of 390-degrees-C for 1/2 h and at 400-degrees-C for 5 min on the magneto-mechanical coupling and ultrasound velocities in Fe79Si12B9 metallic glasses is discussed. Annealing at 390-degrees-C improves the magnetomechanical coupling (k(m) = 0.37). However, after annealing at 400-degrees-C the samples become partially polycrystalline and k(m) drops to 0.2. The results are compared with those obtained previously after annealing in air