THE RELATION BETWEEN THE PLASTIC DEFORMATION OF ALUMINUM SINGLE CRYSTALS AND POLYCRYSTALS. Final Report

Technical Report · Sun May 01 04:00:00 EDT 1960

OSTI ID:4183525

Howe, S; Elbaum, C

Single crystals of {100}, {111}, and {110} axial orientation, and polycrystals, both of 99.99% pure aluminum, were deformed in tension at temperatures of 27, 200, 400, and 600 tained C. The experiments on single crystals revealed that as the temperature increased, the shear stress- shear stran-n curves for the three orientations became more and more similar until at 600 tained C they were identical. On the other hand the surface appearance of the crystals strained at 600 tained C indicated that the mcde of deformation depended drastically on orientution. Taylor's criterion for the comParison of the stress-strain curwes of single and polycrystals was found to be valid at 27 tained C. As the temperature was raised, however, the cniterion ceased to be applicable. From the results of these experiments it is proposed that at the lower temperatures in both single crystals and polycrystals the principal hardening mechanism is the formation of Lomer-Cottrell barriers that act ae obstacles against which glide dislccations can pile up. As the temperature is rsised these barriers become ineffective as obstacles to slip, whereas grain boundaries in polycrystals continue to be effective in causing dislocation pile-ups. (auth)

• Research Organization: Brown Univ., Providence. Metals Research Lab.
• NSA Number: NSA-14-019432
• OSTI ID: 4183525
• Report Number(s): NP-8855
• Country of Publication: United States
• Language: English

Related Subjects

ALUMINUM
BARRIERS
CONFIGURATION
CRYSTALS
DEFORMATION
DIAGRAMS
DUCTILITY
GRAIN BOUNDARIES
HIGH TEMPERATURE
IMPURITIES
METALS, CERAMICS, AND OTHER MATERIALS
MONOCRYSTALS
SHEAR
SLIP
STRESSES
SURFACES
TEMPERATURE
TEMPERING
TENSILE PROPERTIES
TESTING