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High-temperature stress-strain behavior of MgO in compression

Conference · · J. Am. Ceram. Soc.; (United States)
OSTI ID:5643485
Compressive stress-strain curves for several types of polycrystalline MgO specimens were correlated with those for single crystals and analyzed as a function of grain size and grain-boundary character at 1200 and 1400/sup 0/C for several strain rates. The results for fully dense specimens were explained in terms of grain-boundary sliding and intergrainular separation in addition to slip. The modification of grain-boundary nature concurrent with heat treatment for grain growth, caused by residual Li/F, was associated with enhanced grain-boundary sliding and intergranular separation. For grain sizes < 30 ..mu..m, it was concluded that the von Mises criteria for ductility could be relaxed by the occurrence of dislocation climb and, to a limited extent, by intergranular separation. Yield drop corresponding to dislocation multiplication occurred when grain-boundary sliding was initially promoted. Specimens with a liquid phase of adequate viscosity also indicated plasticity accompanied by high strength. Specimens with clean grain boundaries exhibited ductility and normal strain hardening with no intergraular separation.
Research Organization:
Univ. of California, Berkeley
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
5643485
Conference Information:
Journal Name: J. Am. Ceram. Soc.; (United States) Journal Volume: 62:9-10
Country of Publication:
United States
Language:
English