TWINNING AND THE LOW TEMPERATURE MECHANICAL PROPERTIES OF POLYCRYSTALLINE COLUMBIUM AND MOLYBDENUM.

Abstract

Mechanical properties of Cb and Mo have been investigated over a range of grain sizes from 20 C to minus 269 C. Interpretation of the load elongation curves, in compression and tension, along with detailed metallographic investigation has led to the following conclusions: (1) Twinning can occur more readily in coarse grain than fine grain material, (2) Twins can occur over the entire range of temperature 20 C to minus 269 C in molybdenum but only in the range minus 150 to minus 269 C in columbium at Epsilon = 0.00042/sec; and (3) Enhanced stresses ahead of a crack can cause twinning but there is no definite evidence to show that twins cause cracking. These results have been interpreted in terms of a model independent hypothesis, based on simple considerations of the dissipation of energy by various deformation mechanisms. (Author)

Document Details

Document Type
Technical Report
Publication Date
Jan 01, 1966
Accession Number
AD0477694

Entities

People

  • Bevil J. Shaw
  • Donald L. Harrod

Tags

DTIC Thesaurus Topics

  • Compression
  • Dissipation
  • Elongation
  • Grain Size
  • Low Temperature
  • Materials
  • Mechanical Properties
  • Molybdenum
  • Niobium
  • Physical Properties
  • Polycrystals

Readers

  • Materials Science and Engineering.
  • Mechanical Engineering/Mechanics of Materials.