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Deformation of Polycrystalline MgO Under Pressure
Author(s) -
PATERSON M. S.,
WEAVER C. W.
Publication year - 1970
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1970.tb12678.x
Subject(s) - slip (aerodynamics) , materials science , crystallite , homogeneous , deformation (meteorology) , composite material , overburden pressure , slip line field , mechanics , thermodynamics , geology , geotechnical engineering , metallurgy , physics
Polycrystalline MgO appears to deform ductilely when it is strained under confining pressures greater than 2 kbars at room temperature. Although the {110}〈110〉 slip systems in MgO do not provide the five independent slip systems required for homogeneous deformation, the lack is apparently met in part by the activity of additional slip systems and in part by microfracture. The strong pressure dependence of the stress‐strain curves probably arises from the pressure sensitivity of microfracture, which becomes less important as the temperature is raised; high‐temperature experiments at 2 and 5 kbars confining pressure show that the pressure dependence virtually disappears at 750°C and that there is a simultaneous trend toward wavy slip. High‐temperature experiments on single crystals oriented for cube slip produced only kinking below 300°C; above 300° there is some cube slip, but it is not clear that this is a major deformation mechanism. The pressure dependence of the fracture and flow stresses is interpreted in terms of recent theories of crack propagation under pressure.