Homogeneous Flow in Metallic Glasses

Creep of an iron based glassy alloy (FeBSiC) is studied: both aspects (viscoelastic and viscoplastic) of deformation, the relation between strain rate and stress, and the effect of structural relaxation are precised. A model of homogeneous deformation of metallic glasses near Tg, able to take all the experimental features into account, is proposed. Following such a model, the plastic deformation would be principally dependent on recovery processes associated to structural relaxation. Le fluage d'un alliage vitreux FeBSiC a ete etudie: le caractere a la fois viscoelastique et viscoplastique de la deformation, la relation entre vitesse de deformation et contrainte appliquee et, enfin, l'effet de la relaxation structurale ont ete precises. Apres avoir discute certains hypotheses physiques, un modele de deformation homogene pouvant rendre compte du comportement des verres metalliques vers Tg, est propose. Selon ce modele, la deformation plastique, serait essentiellement commandee par des processus de restauration associes a la relaxation structurale.