Magnetic properties and loss separation in Fe76−xAgxNb2Si13B9 amorphous alloys

• Soft magnetic properties can be optimized by applying a suitable heat treatment.
• Low field magnetic permeability of the optimized samples increases about 10 times.
• Total magnetic loss of the optimized samples decreases at least 10 times.
• Plasticity is much higher than that reported for similar nanocrystalline alloys.
• Observed effects are attributed to formation of the relaxed amorphous phase.

Some selected properties (magnetic, plastic, elastic) in amorphous Fe76−xAgxNb2Si13B9 (x = 0.5, 0.75, 1.0) alloys, obtained by melt spinning technique, are presented and discussed in detail. It was shown that a suitable heat treatment of the as quenched samples (i.e. the optimization annealing) leads to a significant improvement of soft magnetic properties (permeability increases at least 10 times). The observed effect is attributed to formation of the so-called relaxed amorphous phase free of iron nanograins. Special attention is paid for loss separation into different components: hysteresis loss, eddy-current loss and residual loss. The latter effect can be attributed to diffusion of free volume and practically disappear after the optimization annealing.