I. THE FRACTURE BEHAVIOR OF MAGNESIUM OXIDE BI-CRYSTALS. II. THE EFFECT OF SURFACE CONDITION ON THE MECHANICAL PROPERTIES OF LITHIUM FLUORIDE CRYSTALS. Interim Technical Report

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

OSTI ID:4123392

Westwood, A R.C.

Metallographic studies on compressed bicrystals of MgO revealed cracks formed at the boundary by the cooperation of two slip bands which met at the boundary. Cracks associated with a single pile-up were not observed. A dislocation mechanism for crack formation at low strains is proposed. In other work a comparative study was made of the behavior of as-cleaved chemically polished and coated LiF crystals. Coatings affected all stages of the deformation process, in some cases causing stress drops and reducing the stress and strain to fracture by one-half. Metallographic evidence for the piling up of dislocations beneath surface films is presented together with an explanation for the experimental re sults, which appear consistent with a barrier mechanism of work hardening. (auth)

• Research Organization: RIAS. Div. of Martin Co., Baltimore
• NSA Number: NSA-15-000640
• OSTI ID: 4123392
• Report Number(s): WAL-TR-832.1/1
• Country of Publication: United States
• Language: English

Related Subjects

CLEANING
COATING
CRACKS
CRYSTALS
DEFECTS
DEFORMATION
DISLOCATIONS
FAILURES
FILMS
GRAIN BOUNDARIES
LITHIUM FLUORIDES
MAGNESIUM OXIDES
MECHANICAL PROPERTIES
METALLOGRAPHY
METALS, CERAMICS, AND OTHER MATERIALS
STRESSES
SURFACES
TEMPERING