High temperature plastic deformation of amorphous-crystalline structures

There has been investigated fluidity of zircon ZrSiO4. To improve sintering, there has been introduced 0.8% of TiO2. After annealing at 1500 deg C the specimens have shown the density of 4.40 g/cm3 at overall porosity of 4.5%. The content of the basic component has amounted to about 97%. The microstructural investigations have shown that the size of the grains approximates 3 microns and that thin envelopes of the vitreous phase are formed around the grains. The high-temperature plasticity of the specimens is characterized by the stable rate of creepage which has been measured during pure bending in vacuum of about 10-5 mm Hg. There has been shown the dependence of the creepage rate on the temperature, which demonstrates that the effective energy of activation is constant at various stresses. At the creepage rates of vsub(np)=vsigmasup(-n) there has been obtained Q approximately 205 Kcal/mole. Thus, there has been obtained the expression for viscosity of the amorphous-crystal systems which are deformed due to slipping of the non-bound crystal grains on the amorphous interlayer. This has made it possible to explain the discrepancy between viscosity of the refractories and content of the glass. As an example, there has been studied high-temperature creepage of zircon whose structure is sufficiently adequate to the discussed model