It is shown that gradual devitrifiation of non-magnetostrictive Go-based me
tallic glass leads to a giant, five orders of magnitude, increase of its co
ercivity. This magnetic hardening is due to the pinning of domain walls by
growing fine crystallites much smaller than the domain wall width, the numb
er and size of which increase with an increase of the annealing temperature
. (C) 1999 Elsevier Science B.V. All rights reserved.