Title

Research and Development on Advanced Graphite Materials: Volume II - Applications of Anisotropic Elastic Continuum Theory to Dislocations in Graphite

Date

1962

Index Abstract

Contrails and DTIC truncated

Photo Quality

Not Needed

Report Number

WADD TR 61-72 Volume II

Corporate Author

National Carbon Company

Laboratory

Directorate of Materials and Processes

Extent

54

Identifier

AD0286090

AD0286090

Access Rights

OTS

Distribution Classification

1

Contract

AF 33(616)-6915

DoD Project

7350

DoD Task

735002

DTIC Record Exists

No

Distribution Change Authority Correspondence

None

Abstract

Eshelby, Read, and Shockley's theory of dislocations in an anisotropic elastic continuum has been used to derive formulas not involving complex numbers for the stress components of straight dislocations in certain symmetry directions. From these the dependence of stacking fault energy γF on the orientation of the Burgers vector and on the width of extended dislocations and triple partial ribbons and the dependence of γF on the radius of curvature of extended nodes were calculated. The results are rigorous for hexagonal crystals and approximate for general directions in (111) planes of FCC crystals. The theory is applied to graphite and lose-packed metals. All three methods of determining γF for graphite yield results which are compatible with the value 0.6 ± 0.2 erg/cm2. The rough estimate of error is based on uncertainties in the elastic constants and differences in experimental results. The dependence of width on depth from the stress-free surface has been calculated for an arbitrarily oriented dislocation lying parallel to the surface of a semi-infinite isotropic body and 30° extended dislocation and a symmetrical, screw triple partial ribbon in certain symmetry directions in an anisotropic plate. A procedure for correcting the widths observed in electron microscopy of thin films is given.

Report Availability

Full text available

Date Issued

1962-07

Subject

Graphite

Stresses

Bibliographies

Crystals

Deformation

Elastic Properties

Mathematical Analysis

Surfaces

Theory

Publisher

Wright-Patterson Air Force Base, OH : Directorate of Materials and Processes, Aeronautical Systems Division, Air Force Systems Command

Distribution Conflict

No

Provenance

Lockheed Martin Missiles & Fire Control

Type

report

Format

1 online resource

Creator

Spence, G. B.