Dislocation Velocities, Dislocation Densities, and Plastic Flow in Lithium Fluoride Crystals
- 1 February 1959
- journal article
- conference paper
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 30 (2) , 129-144
- https://doi.org/10.1063/1.1735121
Abstract
Velocities of individual dislocations have been measured in LiF, covering a range of twelve orders of magnitude in velocity, from 10−7 cm/sec to 105 cm/sec. The velocity is extremely sensitive to applied stress at low velocities, and for each crystal there exists a minimum stress for dislocation motion, below which dislocations do not move. The edge components of dislocation loops move considerably faster than the screw components. The upper limit for dislocation velocity appears to be the velocity of sound in the crystal. The effects of temperature, impurities, and radiation damage on dislocation velocity are described. These variables affect the dynamic resistance to motion encountered by a moving glide dislocation. The growth of total dislocation density, the growth of individual glide bands, and the distribution of glide dislocations during plastic deformation are described. The yield stress of LiF is determined by the resistance to motion encountered by a glide dislocation in moving through an otherwise dislocation‐free region of the crystal. The yield stress is independent of the dislocations present in an undeformed crystal, and the state of pinning and geometrical arrangement of such dislocations do not affect the yield stress. Stress‐strain curves have been calculated from the data on dislocation mobility and dislocation density, and the calculated and measured curves are compared. At low strains the flow stress can be predicted from measured dislocation properties.This publication has 15 references indexed in Scilit:
- Method for the Detection of Dislocations in Silicon by X-Ray Extinction ContrastPhysical Review B, 1958
- Subgrain Structure in an Fe-Si Crystal as Seen by X-Ray Extinction ContrastJournal of Applied Physics, 1958
- Dislocations, Point-Defect Clusters, and Cavities in Neutron Irradiated LiF CrystalsJournal of Applied Physics, 1958
- Dislocation theory of plastic bendingActa Metallurgica, 1957
- Plastic deformation of germanium in compressionActa Metallurgica, 1956
- LXVIII. Direct observations of the arrangement and motion of dislocations in aluminiumPhilosophical Magazine, 1956
- XXV. The direct observation of dislocation nets in rock salt single crystalsPhilosophical Magazine, 1956
- The ionic conductivity of Li‐halide crystalsRecueil des Travaux Chimiques des Pays-Bas, 1950
- ber eine Art Gitterst rung, die einen Kristall plastisch machen k nnteThe European Physical Journal A, 1934
- Zur Kristallplastizit t. IIIThe European Physical Journal A, 1934