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An experimental study of the mobility of edge dislocations in pure copper single crystals

Citation

Jassby, Kenneth Mark (1970) An experimental study of the mobility of edge dislocations in pure copper single crystals. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:07182014-114729703

Abstract

The velocity of selectively-introduced edge dislocations in 99.999 percent pure copper crystals has been measured as a function of stress at temperatures from 66°K to 373°K by means of a torsion technique. The range of resolved shear stress was 0 to 15 megadynes/ cm^2 for seven temperatures (66°K, 74°K, 83°K, 123°K, 173°K, 296°K, 296°K, 373°K.

Dislocation mobility is characterized by two distinct features; (a) relatively high velocity at low stress (maximum velocities of about 9000 em/sec were realized at low temperatures), and (b) increasing velocity with decreasing temperature at constant stress.

The relation between dislocation velocity and resolved shear stress is:

v = v_o(τ_r/τ_o)^n

where v is the dislocation velocity at resolved shear stress τ_r, v_o is a constant velocity chosen equal to 2000 cm/ sec, τ_o is the resolved shear stress required to maintain velocity v_o, and n is the mobility coefficient. The experimental results indicate that τ_o decreases from 16.3 x 10^6 to 3.3 x 10^6 dynes/cm^2 and n increases from about 0.9 to 1.1 as the temperature is lowered from 296°K to 66°K.

The experimental dislocation behavior is consistent with an interpretation on the basis of phonon drag. However, the complete temperature dependence of dislocation mobility could not be closely approximated by the predictions of one or a combination of mechanisms.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Materials Science
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Materials Science
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Vreeland, Thad
Thesis Committee:
  • Unknown, Unknown
Defense Date:7 July 1969
Record Number:CaltechTHESIS:07182014-114729703
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:07182014-114729703
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8565
Collection:CaltechTHESIS
Deposited By: John Wade
Deposited On:18 Jul 2014 19:59
Last Modified:18 Jul 2014 19:59

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