High pressures plastic deformation under

High-stress plastic deformation under a confining pressure up to 1.5 GPa 59... 

High-stress plastic deformation under a confining pressure up to 1.5 GPa The first work on the deformation of silicon under hydrostatic pressure as a way to reach high stresses was performed by Castaing et al. [54], using a Griggs apparatus... 

The series of experiments allows the conclusion that plastic deformation by itself (of which the systems under study are, in principle, capable) cannot initiate the development of the autowave process without the occurrence of brittle fracture. Therefore, creation of high but plastically deforming pressures is not a sufficient condition for the initiation of autowave processes. In order to... 

This conclusion was confirmed also by a different series of experiments elucidating the role of plastic deformations. The experiments were performed in the regime of practically uniform rather than local loading. To this end we employed the procedure developed to study the initiation and development of autowave processes under conditions of uniform compression (see Section VII). But whereas previously what were subjected to y radiation were massive samples under conditions of high static pressure (i.e., the stage of accumulation of active centers in the sample was preceded by plastic deformation during compression), in this work the experimental procedure was modified to fit the task formulated above. 

Secondly, they showed that under the high hydrostatic pressures generated in contact of a crystalline material (rock-salt) and a steel slider the rock-salt ceases to be brittle, and can undergo marked plastic deformation. Such plastic deformation in... 

The transition from crystalline to melt state, which is normal for crystalline polymers, is not observed with cellulose under normal conditions. It appears that the secondary bonds giving rise to the crystalline state are too strong and too numerous to be broken by a rise in temperature. Thermal degradation (beginning at ca. 180 °C) precedes melting under atmospheric pressure conditions. Nevertheless, a plastic deformation interpreted as melting has recently been reported for cellulose fibers exposed to laser radiation in a highly confined (pressurized) space [43]. The fracture surface of a thermoplastically deformed cellulose disc is shown in e Fig. 10. 

The deviations from the average value for the utmost points of the curve do not exceed 0.1 GPa (6 %). This result is an evidence of the fact that a porous body from the quasicrystalline powder deforms under a high quasihydrostatic pressure as porous bodies from plastic material. Thus, it is shown that the effective pressure P for the consolidation of a powder billet of Al63Cu25Fei2 in the high-pressure apparatus is... 

A large X-ray line broadening in both (1- and /-phases in compacted samples (Fig. 3) is an evidence of a strong plastic deformation in compact samples sintered under high quasihydrostatic pressure. 

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