Shear Modulus Of Glass Research Articles

Dependence of the glass shear modulus on the crystal shear modulus and the structural relaxation kinetics for the Zr46Cu46Al8 system

It has been shown that the temperature coefficient of the shear modulus of the Zr46Cu46Al8 glass at a constant concentration of frozen-in “defects” such as dumbbell interstitials is identical to that of the same alloy in the crystalline state. Relaxation of the “defect” subsystem leads to positive or negative changes in this coefficient, depending on the sign of change in the “defect” concentration. The “defect” concentration is calculated in the initial and relaxed glass states as functions of temperature for different heating rates and thermal prehistories.

Shear modulus of glasses: results from the full replica-symmetry-breaking solution.

We compute the shear modulus of amorphous hard and soft spheres, using the exact solution in infinite spatial dimensions that has been developed recently. We characterize the behavior of this observable in the whole phase diagram, and in particular around the glass and jamming transitions. Our results are consistent with other theoretical approaches, which are unified within this general picture, and they are also consistent with numerical and experimental results. Furthermore, we discuss some properties of the out-of-equilibrium dynamics after a deep quench close to the jamming transition, and we show that a combined measure of the shear modulus and of the mean square displacement allows one to probe experimentally the complex structure of phase space predicted by the full replica-symmetry-breaking solution.

Maxwell equation and classical theories of glass transition as a basis for direct calculation of viscosity at glass transition temperture

The main relaxation theories of glass transition (Leontovich-Mandelstam and Volkenstein-Ptitsyn) variously formulate the kinetic criteria of glass transition. Both of the approaches are shown to be equivalent in physical sense and provide a single expression that connects the rate of change of a melt temperature and the structure relaxtion time. The theory characterizes the width of a temperature band δTg in which the glass transition occurs. The values of δTg can either be obtained from the experiment or be accepted to conform to the value of a temperature step under the change of viscosity by an order of magnitude (direct method for finding by the Volkenstein-Ptitsyn theory). Using the Maxwell equation, a new equation for the calculation of the viscosity for viscoelastic relaxation was suggested, which is based on a shear modulus of glass and the cooling rate. The theory was verified basing on the published data for oxide glass. The average difference between the calculated and measured values of lgη upon glass transition comprises 0 ± 0.30. These results correspond to the cooling rate of 3 K/min and log(η, Pa s) = 12.76 ± 0.26 (for all glass considered). It is shown that the most probable cooling rate which provides the viscosity upon glass transition of ∼1012 Pa s is close to 20 K/min (oxide melts). The theory predetermines the dependence of viscosity upon glass transition on the nature of a glass-forming liquid. The disadvantages of other approaches to the problem under consideration are demonstrated.