STRUCTURAL RELAXATION AND CRYSTALLIZATION OF FeB AND NiP METALLIC GLASSES FOLLOWED BY INTERNAL FRICTION AND MODULUS MEASUREMENTS

Abstract
The dynamic elastic modulus and internal friction of metallic glasses was measured by a torsional pendulum with low inertial momentum and low external damping. The internal friction measured during heating increases rapidly above 100°C, and near the crystallization temperature it decreases suddenly. At the same time a modulus jump in one or two steps was found during crystallization in a narrow temperature range. Isothermal measurements in the crystallization range show that an incubation time is needed and the velocity of this process depends on temperature as well. A large continuous increase in the dynamic elastic modulus was observed far below the crystallization temperature in a wide temperature range above 100°C. This is probably caused by a structural relaxation process in the amorphous state. No relaxation peak above room temperature was found neither in glassy nor in crystallized state.