EFFECT OF SLIP DISTRIBUTION ON THE FRACTURE BEHAVIOR OF MAGNESIUM OXIDE SINGLE CRYSTALS. Technical Report No. 8

Technical Report · Wed Jun 01 04:00:00 EDT 1960

OSTI ID:4135305

Stokes, R J; Johnston, T L; Li, C H

The tensile deformation of chemically polished MgO crystals was correlated with the distribution of slip at the onset of plastic flow. U two slip bands, generated on orthogonal {1 1 0} planes, happen to intersect to nucleate a crack before other slip bands develop nearby, then the crack so formed was found to be unstable and the crystal completely brittle. It is shown that if a higher density of slip sources exists, cracks become stabilized by adjacent slip bands and the crystals continue to deform. If slip is confined to a single slip band which expands laterally to fill the entire gage length, these crystals were determined to be extremely ductile. The fracture behavior of a given crystal depended critically upon the relative orientation, number, thickness, and spacing between slip bands. It was found that the density of slip can be increased artificially when dislocation sources are injected into the crystal surface by sprinkling with carborurdum before loading. Such crystals were always ductile in tension. A similar treatment for crystals to be bent led to a profound change in their fracture behavior. (auth)

• Research Organization: Honeywell Research Center, Hopkins, Minn.
• NSA Number: NSA-14-025935
• OSTI ID: 4135305
• Report Number(s): HR-60-479
• Country of Publication: United States
• Language: English

Related Subjects

BRITTLENESS
CRACKS
DEFECTS
DEFORMATION
DENSITY
DISLOCATIONS
DISTRIBUTION
DUCTILITY
FAILURES
LATTICES
MAGNESIUM OXIDES
METALS, CERAMICS, AND OTHER MATERIALS
MONOCRYSTALS
REPORT
SLIP
STABILITY
SURFACES