Influence of heat treatment on the magnetic properties and structure of Fe-Pt alloys

It is established that there are two basic mechanisms of formation of an ordered L1 0 phase during annealing of Fe-Pt alloys: one continuous (causing formation of a tweed structure), one discontinuous. At high annealing temperatures (800-850 o C) the continuous formation fo highly dispersed domains of ordered phase predominates and a high level of the magnetic properties is attained (B r =1.02 T, H c =320 kA/m, (BH) max =128 kJ/m 3 ). At lower temperatures grain-boundary migration becomes intensive, and is accompanied by rapid growth of c-domains as well as the formation of recrystallized grains. The larger grains and domains have higher lattice tetragonality than the internal volumes of grains that order by the continuous mechanism. This type of structure results in a lower level of the magnetic properties