University of Illinois Urbana-Champaign

Yield behavior of niobium single crystals

Huffaker, D.C.

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https://hdl.handle.net/2142/111988

Description

Title
Yield behavior of niobium single crystals
Author(s)
Huffaker, D.C.
Issue Date
1964-09
Keyword(s)
  • Yield Behavior
  • Niobium
Abstract
The yield behavior of niobium single crystals has been studied under conditions of different temperatures, strain rates, and microstructure. The effect of temperature and strain rate on the yield strength on the single crystal material investigated with <110> direction parallel to the compression axis seems to be characterized by the modified form of the rate process equation γ ̇ = Ae^(-(∆H* -V(τ- τ_i))/RT) where γ ̇ = Strain rate (resolved on the (110) plane and in the <111> direction) A = Frequency factor ∆H* = Activation energy at zero effective stress V = Activation volume τ = Observed stress (resolved on the (110) plane and in the <111> direction) τ_i = Internal (frictional) stress R = Universal gas constant T = Temperature, degrees Kelvin Within the range of variables studied the frequency factor has been found to be independent of stress, temperature and microstructure and has a value around 107/sec for the material investigated. The activation volume has been found to be dependent upon stress but independent of microstructure. The internal (frictional) stress has been shown to vary with the dislocation density as determined by etch pitting and optical microscopy. Furthermore, the frictional stress has been found to vary in an amount approximately proportional to the square root of the dislocation density.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
  • TAM R 268
  • 1967-0564
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/111988
Sponsor(s)/Grant Number(s)
Atomic Energy Commission, Contract No. AT (11-1)-1046
Copyright and License Information
Copyright 1964 Board of Trustees of the University of Illinois

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Technical Reports - Theoretical and Applied Mechanics (TAM) PRIMARY
TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.