THE EFFECT OF HIGH TEMPERATURE RECOVERY ON THE CREEP OF POLYCRYSTALLINE ALUMINUM IN THE DISLOCATION CLIMB REGION OF TEMPERATURES. Period covered January 31, 1958 to January 31, 1959

Technical Report · Sun Feb 01 04:00:00 EST 1959

OSTI ID:4167087

Ludemann, W D; Shepard, L A; Dorn, J E

The creep resistance of 99.99% pure aluminum was studied at 540, 573, 600, and 611 deg K. Polycrystalline specimens crept under a stress of 950 psi to a strain of 5.5% were allowed to recover for periods of from one minute to sixteen days under a residual stress of 4.4 psi. Increased creep rates upon reapplication of the 950 psi stress evidenced softening of the material. The activation energy for the recovery process was found to be 64,000 cal/mole. Metallographic studies of the specimens showed relief of local elastic strains by coalescence of dislocations into subgrain boundaries upon recovery, and sub- boundary migration. The activation energy of 64,000 cal/mole indicates that recovery of creep resistance was due primarily to the sweeping out of dislocations within the grains by the migration of subboundaries. Indications of minor grain growth here also found. (auth)

• Research Organization: California. Univ., Berkeley. Inst. of Engineering Research
• NSA Number: NSA-14-008755
• OSTI ID: 4167087
• Report Number(s): WADC-TR-59-131
• Country of Publication: United States
• Language: English

Related Subjects

ACTIVATION ENERGY
ALUMINUM
CREEP
CRYSTALS
DEFECTS
DEFORMATION
DISLOCATIONS
ELASTICITY
EXPANSION
GRAIN BOUNDARIES
GRAIN SIZE
IMPURITIES
METALLOGRAPHY
METALS, CERAMICS, AND MATERIALS
PRESSURE
RECOVERY
STRESSES
TEMPERATURE
THERMODYNAMICS