QUENCHING EFFECTS IN A Fe40Ni40P14B6 AMORPHOUS ALLOY STUDIED BY MAGNETIC ANISOTROPY MEASUREMENTS

Kinetics for the establishment of the magnetic anisotropy has been found to be a reversible function of the equilibrium structural state quenched in from different temperatures (activation energy : 0.28 + 0.02 eV) Introduction tic anisotropy developnent as a function of the Amorphous metallic alloys quenched from the quench temperature, T Such kinetics are measured 0' melt are known to be in an out-of-equilibrium state during an isothermal thermomagnetic treatment (TMT) and to show a structure change when annealed at at a fixed temperature, TA = 160°C, after the samtemperatures for below the crystallization tempeples were quenched down from different temperatures, rature, T ~ ' To. This relaxation affects most of the physical properties [I-61, and must be considered as due to variations of topological (TSRO) and/or chemical (CSRO) short range order [71. Physical properties depend more or less on either of these orders. At least in some cases [8-101, it is obviously not a matter of crystallization first step, but rather an evolution of the amorphous phase towards a metastable equilibrium state. So, a fundamental question is asked about the possible reversibility of this state along with the anneal temperature. Such a reversibility at least for one part has been established for Curie temperature [7,11], electrical resistivity [12] and magnetic anisotropy [13183 ; the latter one varies also reversibly as a function of direction of the applied magnetic field These three properties seem to reflect mainly CSRO