Copy D an Experimental Study of 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 a torsion technique. The range of resolved shear stress was 0 to 15 megadynes/cm2 for seven temperatures (66°K, 74°K, 83°K, 123°K, 173°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 0 I I where vis the dislocation velocity at resolved shear stress ,. r , v 0 is a constant velocity chosen equal to 2000 em/sec, T 0 is the resolved l (_