The Mobility of Edge Dislocations in Pure Copper Single Crystals

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 the torsion technique developed by Pope, Vreeland, and Wood (1967). 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, 373°K). The path of motion of individually displaced dislocations was traced from Berg-Barrett x-ray micrographs, while the etch pit technique was used to indicate the crossing of forest dislocations. The test crystals were free from substructure with a grown-in dislocation density between 10^3 and 10^4 cm/cm^3. The dislocations were between 0.01 and 0.02 cm in length and displacements varied between 0 and 0.1 cm, so that in the extreme case the intersection of forest dislocations was reduced to zero.