EFFECT OF DILUTE COPPER ALLOYING ON THE ACTIVATION ENERGIES FOR CREEP OF ALUMINUM SINGLE CRYSTALS. Technical Report No. 7

Technical Report · Mon Dec 01 04:00:00 EST 1958

OSTI ID:4245403

Walton, D; Shepard, L A; Dorn, J E

The activation energies for creep of single crystals of Al containing up to 0.25% Cu in alpha solid solution were determined over the range from 78 to 850 deg K. Single crystals were prepared from the melt in a special graphite mold. All crystals were seeded for an orientation that yields extensive easy glide in tension. Activation energies for creep were determined by the effect of small changes in temperature on the creep rate. From 78 to 200 deg K the alloy single crystals exhibited the same activation energy of about 4,000 cal/mole as pure Al crystals. From about 240 to 400 deg K strain aging prevented the determination of the activation energies since the creep rate was found to be negligible; the plastic strain was found to be essentially a function of the applied stress alone in this range. Between 450 and 490 deg K the activaiion energy for creep of the alloys increased from 35,000 to about 41,000 cal/mole; and from 490 to about 700 deg K, over the range where pure Al single crystals exhibit the activation energy of 28,000 cal/mole for cross slip, alpha solid solution alloys of Al containing 0.09 to 0.25% Cu yielded a new activation energy of 41,000 cal/mole. This high activation energy can be rationalized in terms of a modification of the activation energy for cross slip due to solute atom effects. Above about 8OO deg K the activation energy for creep of the Cu alloys of Al was 36,000 cal/mole, a value coincident with that for the dislocation climb process in high-purity Al. (auth)

• Research Organization: California. Univ., Berkeley. Minerals Research Lab.
• NSA Number: NSA-13-011863
• OSTI ID: 4245403
• Report Number(s): NP-7463
• Country of Publication: United States
• Language: English

Related Subjects

ACTIVATION ENERGY
ALUMINUM
COPPER ALLOYS
CREEP
DEFECTS
DEFORMATION
DISLOCATIONS
GRAPHITE
MELTING
METALLURGY AND CERAMICS
MONOCRYSTALS
PREPARATION
SLIP
SOLID SOLUTIONS
TEMPERATURE
TENSILE PROPERTIES
THERMODYNAMICS