Accession Number : AD0607282

Title :   DEFORMATION MECHANISMS OF REFRACTORY AND OTHER MATERIALS.

Descriptive Note : Final rept.,

Corporate Author : GENERAL ELECTRIC CO SCHENECTADY N Y

Personal Author(s) : Johnston,W. G. ; Nadeau,J. S.

Report Date : AUG 1964

Pagination or Media Count : 8

Abstract : This report covers an experimental study of the dynamical flow properties of Al2O3 single crystals at elevated temperatures, and several aspects of deformation behavior of other nonmetallic crystals, principally MgO and alkali halides. The work includes an investigation of the flow stress of pure and doped alkali halides, in the temperature range of 20.5 to 300K. Most of the work with doped crystals has been in crystals of NaCl and LiF containing divalent impurities present and impurity-vacancy pairs. The flow stress at low temperature (20.5K) is compared with Fleischer's theory of hardening by defects that produce tetragonal distortions. The effect of heat treatment on doped crystals is described, as well as the effect of OH(-) or F(-) ions in NaCl doped with devalent metal impurities. An experiment is described in which an attempt was made to align, by means of optical techniques, the defects produced by irradiation in alkali halides. Further experiments on strain rate sensitivity are described for pure, doped and radiation-hardened crystals. A comparison is made between indentation hardness measurements and flow stress measurements in alkali halide crystals, and the pronounced differences in the two types of measurements are discussed. (Author)

Descriptors :   (*REFRACTORY MATERIALS, DEFORMATION), (*DEFORMATION, MATERIALS), ALUMINUM COMPOUNDS, OXIDES, SINGLE CRYSTALS, MAGNESIUM COMPOUNDS, HALIDES, ALKALI METAL COMPOUNDS, SHEAR STRESSES, IMPURITIES, CRYSTAL DEFECTS, HARDNESS, STRESSES, OPTICAL ANALYSIS, SODIUM COMPOUNDS, CHLORIDES, LITHIUM COMPOUNDS, FLUORIDES, TEMPERATURE

Distribution Statement : APPROVED FOR PUBLIC RELEASE