Stability of magnetic properties of metallic glasses

Most of the magnetic and mechanical properties of metallic glasses held at ambient temperature and above are known to change with time. This paper surveys recent results that are of both scientific and technical interest, with particular emphasis on the role of magnetic anisotropy in the relaxation of core loss and permeability. It is shown that most of the relaxations are describable by a kinetic in which the change is approximately linear in the logarithm of the time at the aging temperature. Such effects are the result of processes with a distribution of activation energies. Important implications for the design of experiments and for the evaluation of materials for use at elevated temperatures are exhibited.