Accession Number : AD0431615

Title :   THE MECHANICAL BEHAVIOR OF MAGNESIUM OXIDE AT HIGH TEMPERATURES,

Corporate Author : HONEYWELL RESEARCH CENTER HOPKINS MINN

Personal Author(s) : Day,R. B. ; Stokes,R. J.

Report Date : JAN 1964

Pagination or Media Count : 48

Abstract : Magnesium oxide crystals show a wide variety of deformation and fracture modes under tension at high temperatures depending on the number of slip systems operating concurrently in a given volume. At low temperatures slip is confined to a single <110> (110) system and plasticity is limited by stress concentrations which develop where slip switches from one plane to another. At intermediate temperatures <110> (110) slip systems at 90 degrees to each other can interpenetrate but those at 60 degrees cannot. At high temperatures dislocations can interpenetrate on all systems and polygonization can occur. After easy glide the crystals work harden and elongate over 100 percent before fracturing in a completely ductile manner. The transition from one mode to another depends on strain rate. The relative ability for 90 or 60 degree systems to intersect is discussed in terms of dislocation interactions. (Author)

Descriptors :   (*MAGNESIUM COMPOUNDS, OXIDES), (*OXIDES, MECHANICAL PROPERTIES), (*SINGLE CRYSTALS, MAGNESIUM COMPOUNDS), HIGH TEMPERATURE RESEARCH, DEFORMATION. FRACTURE (MECHANICS), PLASTIC PROPERTIES, CRYSTAL DEFECTS, CRYSTAL STRUCTURE, STRESSES, STRAIN (MECHANICS), CERAMIC MATERIALS, ETCHED CRYSTALS, CREEP, SYMMETRY (CRYSTALLOGRAPHY)

Distribution Statement : APPROVED FOR PUBLIC RELEASE