Strain relaxation and internal friction in the range of the glass transition

For the investigation of structural relaxation near the glass transition qu asistatic creep after-effect measurements have been performed on the alloy Zr65Cu17.5Ni10Al7.5 which shows a large stability above the glass temperatu re T-g. By a separation of anelastic local atomic rearrangements and viscou s long-range diffusion processes the thermal activation parameters of both processes could be determined from Arrhenius diagrams. Below T-g = 606 K an activation enthalpy of 2.1 eV and above T-g an activation enthalpy of 5.6 eV has been determined. For a quantitative description of these relaxation phenomena a new dynamic model is developed which takes into account the con tinuous formation and annihilation of relaxation centers near T-g. From mea surements of the internal friction after rapid temperature changes it could be shown that extended relaxation centers present above T-g become instabl e below T-g and are split up by diffusion processes above 585 K, however, d isappear spontaneously below 580 K.