Substructure and Mechanical Properties of Refractory Metals

Abstract

A coordinated program on W, Mo, Ta and Cb was carried out by ManLabs, M.I.T., Rutgers, U. Liverpool (Eng.) and U. Cambridge (Eng.) by means of advanced microscopic, x-ray diffraction, and mechanical testing techniques. The effective surface energy for fracture of molybdenum strip was found to be about 3000 ergs/sq cm. The tensile ductility transition in Mo is associated with the occurrence of necking. Fibering in W involves formation of ribbon-like grains containing a dislocation cell structure in which fine platelets occur. Discontinuous yielding in Ta single crystals is correlated with a decrease in the shearing strain in the principal slip system to zero while that in the secondary system continues to increase. The binding energy between O atoms and dislocations in Ta is about 0.54 e.v. Dissociation of screw dislocations along three intersecting symmetrically located plates may account for the strong lattice friction stress in b.c.c. metals.

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Document Details

Document Type
Technical Report
Publication Date
Apr 01, 1963
Accession Number
AD0413932

Entities

People

  • B. S. Lement
  • D. A. Thomas
  • P. B. Hirsch
  • S. Weissman
  • W. S. Owen

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Chemistry
  • Crystal Structure
  • Crystals
  • Ductile Brittle Transition
  • Electron Microscopes
  • Geometry
  • Materials
  • Materials Engineering
  • Materials Laboratories
  • Materials Science
  • Materials Testing
  • Mechanical Properties
  • Mechanical Working
  • Shear Stresses
  • Solid Solutions
  • Stress Strain Relations
  • Yield Strength

Readers

  • Materials Science (Mechanical Engineering).
  • Materials Science and Engineering.