Accession Number:

AD0252237

Title:

SOME ASPECTS OF THE ORIGIN OF DISLOCATIONS IN METAL CRYSTALS

Descriptive Note:

Corporate Author:

BROWN UNIV PROVIDENCE R I

Personal Author(s):

Report Date:

1961-02-01

Pagination or Media Count:

1.0

Abstract:

Single crystals of 99.999 pure and zone-refined Al were grown by the Czochralski method at rates of speed that varied from 0.4 to 5 mmmin. The axes of most of the crystals were parallel to a 110 direction. The crystals were carrot-shaped,ABOUT 4 CM LONG, TAPERING FROM A DIAMETER OF ABOUT 3MM AT THE TOP TO ABOUT 0.1 MM AT THE BOTTOM. X-ray diffraction micrographs were taken of the crystals by means of Langs technique, which is capable of revealing the dislocation structure in the interior of a crystal. It was found that the density of dislocations present in an asgrown crystal increases with both increasing diameter and rate of growth. In some cases dislocations were only found on the surface of the crystals these dislocations could be removed by careful electropolishing, thus producing crystals free of detectable dislocations. Author

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Distribution Statement:

APPROVED FOR PUBLIC RELEASE