Accession Number : AD0648375

Title :   VARIATION OF RESOLVED PROPORTIONAL LIMIT WITH MOSAIC ANGLE FROM 77K TO 973K IN ZONE REFINED TUNGSTEN,

Corporate Author : CORNELL UNIV ITHACA N Y

Personal Author(s) : Simpson,Ronald Paul

Report Date : FEB 1967

Pagination or Media Count : 120

Abstract : Tungsten crystals were prepared and purified by electron beam zone refining. A range of mosaic block angles was obtained by controlling the temperature at the molten zone. The tensile axis of the single crystals was determined from Laue back reflection X-ray patterns, and tensile properties were then determined as a function of strain rate and temperature. The resolved proportional limit at constant strain rate of the tungsten crystals varied over a mosaic block angle from 3 to an upper limit of 8 - 10. Both the resolved proportional limit and its range, as a function of mosaic angle, decreased with increasing temperature. Activation volumes were calculated varying inversely with temperature for both mosaic limits. The range of resolved proportional limit with mosaic angle at constant temperature and strain rate is interpreted in terms of the variation of boundary energy with mosaic angle. The tungsten crystals contained interstitial elements in excess of their solubility limit, even though their total interstitial content was below 100 ppm. The elements in solution have an increasing tendency to migrate to the mosaic boundaries with increasing temperature and mosaic angle and consequently have an important effect on the resolved proportional limit. (Author)

Descriptors :   (*TUNGSTEN, *FRACTOGRAPHY), (*CRYSTAL SUBSTRUCTURE, TUNGSTEN), ZONE MELTING, DISLOCATIONS, GRAIN BOUNDARIES, ELECTRON BEAM MELTING, STRAIN(MECHANICS), IMPURITIES, TENSILE PROPERTIES, SINGLE CRYSTALS, CRYOGENICS, HIGH TEMPERATURE

Subject Categories : Metallurgy and Metallography
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE