Accession Number : AD0476108

Title :   DUCTILE-BRITTLE TRANSITION IN REFRACTORY METALS.

Descriptive Note : Summary rept. 1 Jun 64-31 Aug 65,

Corporate Author : RUTGERS - THE STATE UNIV NEW BRUNSWICK NJ BUREAU OF ENGINEERING RESEARCH

Personal Author(s) : Weissmann, S. ; Ellis, T. ; Nanni, L. F.

Report Date : SEP 1965

Pagination or Media Count : 30

Abstract : The distribution of locked-in, residual strains in lightly compressed tungsten crystals with residual strains up to 0.45% has been determined by measuring the changes of interatomic spacings, delta d/d, in different crystallographic directions. It is shown that the delta d/d values measured by the divergent beam method actually represent the resolved elements of an elastic strain tensor which can be described in terms of the three principal strains. With the aid of the principal strains determined it was possible to infer the distribution of the centers of inhomogeneous strains, such as dislocations, which keep the residual elastic strains locked in the crystal. Thus the slip activity in the microstrain region is quantitatively determined. The results obtained are in good agreement with those predicted on the basis of the maximum resolved shear stress operating on potential slip planes. When the centers of inhomogeneous strains become so numerous that they affect the precision of the strain analysis, local broadening of the X-ray line profile occurs. Experimental techniques and results defining sensitively incipient line broadening are presented. (Author)

Descriptors :   (*DUCTILITY, REFRACTORY METALS), (*REFRACTORY METALS, BRITTLENESS), TUNGSTEN, SINGLE CRYSTALS, X RAY DIFFRACTION, STRAIN(MECHANICS), CRYSTAL DEFECTS, SYMMETRY(CRYSTALLOGRAPHY), SHEAR STRESSES, MATHEMATICAL MODELS, REFLECTION, DEFORMATION, COMPRESSIVE PROPERTIES, PURIFICATION, ZONE MELTING, METAL CRYSTALS.

Subject Categories : Metallurgy and Metallography
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE