Europhysics Industrial Workshop EIW-12
Industrial Applications of Positron Annihilation

J. Phys. IV France 05 (1995) C1-151-C1-156
DOI: 10.1051/jp4:1995117

Structural Relaxation in an Amorphous Rapidly Quenched Cobalt-Based Alloy

V. Fradin^{1, 2}, R.I. Grynszpan^{1, 3}, F. Alves², A. Houzali² and J.C. Perron<sup>2

1</sup>  Ecole Nationale Supérieure d'Arts et Métiers, 151 Bd de l'Hôpital, 75013 Paris, France
²  Laboratoire de Génie Electrique de Paris, CNRS-URA 0127, Ecole Supérieure d'Electricité, Plateau du Moulon, 91192 Gif-sur-Yvette cedex, France
³  Laboratoire Pierre Sue - UMR CNRS 9956, CE-Saclay, 91191 Gif-sur-Yvette cedex, France

Abstract
An amorphous melt-spun Co-based alloy (Metglas 2705 MN) is investigated by Doppler Broadening and Positron Lifetime techniques in order to follow the microstructural changes yielded by isochronal annealings before crystallization. The results are correlated with those of Differential Scanning Calorimetry and Coercive Field measurements. The quenched empty spaces underlined by Lifetime measurements are less than one atomic volume in size and migrate without clustering in larger voids. Both Positron Annihilation and Coercive Field investigations suggest that the overall decrease of free volume related to structural relaxation in this amorphous material, proceeds mainly via compositional short-range ordering. These local chemical rearrangements which lead to a partial disorientation of the magnetic moments act as strong pinning points for Bloch Walls.

© EDP Sciences 1995