MOSSBAUER STUDY OF THE STRUCTURE AND STABILITY OF AMORPHOUS FE77.5-X-YMXNYSI13.5B9 ALLOYS

The rf collapse effect is employed to study directly, by using Mossbauer spectroscopy, the quadrupole splitting in the ferromagnetic amorphous Fe77.5-x-yMxNySi13.5B9 alloys, and to derive information about changes of the short-range order when Cu, Nb, and Ta atoms are introduced. The substitution of iron by large Ta atoms caused a marked change of the local structure, while introduction of Nb and Cu did not affect the short-range order. The stability of the amorphous phase is affected by the rf exposure. The high-magnetostriction Fe77.5Si13.5B9 and Fe76.5Cu1Si13.5B9 alloys crystallized due to rf exposure. Lower-magnetostriction alloys containing Nb and Ta remained amorphous without traces of the crystalline phases being detected.