Kinetics and Mechanism of Crystallization of Amorphous Alloy Fe_(85)B_(15) with Soluble Impurities

摘要

Kinetics of crystallization of hypoeutectic amorphous alloy Fe_(85)B_(15) with small (0,01 relative to the Fe content) soluble additions of Co, Nb and Mo having the different surface activities for Fe is studied. The set of obtained results gives and evidence that such additions do not affect the value of energy barrier of nucleation critically. The impurities' effect manifests itself mainly at the stage of primary #alpha#-Fe crystals' growth. If their coefficient of distribution inside iron diminishes, such an effect manifests to a greater extent. The mechanism of influence of soluble additions consists in reducing the growth rate by the formation of enriched impurity layer at the interface that causes the hindered ingress of parent metal atoms into the growing crystal. This effect of impurities manifests itself at the earliest stages of crystal growth.As a result, the dynamic temperature of crystallization is elevated, the activation energy of penetration of atoms through the interface increases in value. The nucleation rates plotted as functions of temperature are shifted to the high-temperatures' region, and as an outcome, a thermal stability of base alloy is built up. It is assumed that, besides the kinetic factors, a possible change of chemical interaction between components upon alloy age with small soluble additions can also favour a complementary thermal stabilization of amorphous alloy.