The results of studying the creep of polycrystalline ceramics based on metal oxides at temperatures up to 1600 ° C and high loads are presented. These temperatures are in the vicinity of the transition from the brittle behavior of the ceramic to the plastic one. The loads are close to the ultimate strength of materials at a given temperature. It is shown that the elementary deformation mechanism in the entire plasticity range of the samples is the diffusion-viscous (vacancy or interstitial) flow with its varieties - the diffusion displacement of dislocations and crystal boundaries. The data obtained agree with the assumption that the transition from brittle fracture of ceramics to plastic in it requires the appearance of a certain critical concentration of vacancies. These vacancies are formed due to thermal activation and determine the deformation of materials. Tab. 1, ill. 3, bibliography: 7 titles.
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