THEORETICAL-ANALYSIS OF STRESS CHANGES DURING STRUCTURAL RELAXATION EXPERIMENTS FOR FE85-XCOXB15 GLASSES

Thermomechanical analysis (TMA) was used to study the aging of rapidly quenched Fe85-xCoxB15 glasses. The three-point flexure technique was principally suitable for this study. The stress relaxation measurement s permitted a characterization of the structural relaxation for variou s compositions. A theoretical approach of the aging of this type of gl ass was built up within the framework of the non-linear relaxation dis tribution (DNLR) model based on irreversible thermodynamics. For sever al isothermal experiments, the reduced property determined from the sa mple deflection was calculated. Then. the three characteristic paramet ers of the DNLR model were deduced:the activation enthalpy, the activa tion entropy, and a parameter of non-linearity. As samples in a relati vely wide concentration range were used, the effect of alloying on the model parameters was examined.