Accession Number:

AD0248450

Title:

NON-ELASTIC UNLOADING OF COPPER AND ALUMINUM

Descriptive Note:

Technical rept.

Corporate Author:

MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s):

Report Date:

1960-11-01

Pagination or Media Count:

15.0

Abstract:

The mechanical hysteresis curves of copper and aluminum single crystals and polycrystalline samples were measured at 25 and -196 degrees C in the plastic strain range of 0.0001. A departure from elastic unloading is ascribed to the motion of piled-up glide dislocations toward their sources. The stress at which reverse plastic flow starts on unloading is associated with the force required for the glide dislocations to cut over through a forest of intersecting dislocations with the formation of a jog. The jog formation energy is calculated to be 1.0 e.v. at 25 C and 1.4 e.v. at -196 C for copper and 0.2 e.v. at 25 C and 0.4 e.v. at -196 C for aluminum. The temperature dependence of the jog formation energy is ascribed to the constriction of stacking faults on the intersection of the partial dislocations. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE