THE EFFECT OF ZONE REFINING ON THE PURITY AND MECHANICAL PROPERTIES OF BERYLLIUM SINGLE CRYSTALS

Technical Report · Thu Aug 01 04:00:00 EDT 1963

OSTI ID:4651358

Kaufman, D F; Levine, E D; Pickett, J J; Aronin, L R

Chemical analyses and resistance ratio measurements showed that zone refining of beryllium results in large reductions in impurity content. The ultimate level of purity reached is strongly dependent on the purity of the starting material. Critical resolved shear stresses for basal and prismatic slip are found to decrease in a regular manner with decreasing impurity content as measured by resistance ratio. In the purity range studied, the absolute decreases in critical stresses for the two processes are approximately equal. The critical resolved shear stress for prism slip is strongly temperature dependent; critical resolved shear stress for basal slip is almost independent of temperature. Purification by zone refining markedly increases the capacity for basal glide and reduces the rate of work hardening. Fracture still occurs by basal cleavage at room temperature, but at elevated temperatures brittle fracture by cleavage is eliminated. Brittle fracture by cleavage accompanying slip on a single set of prismatic planes is eliminated in crystals purified by zone refining. Addition of iron to zone-refined beryllium results in lattice strengthening as measured by critical resolved shear stress for basal slip. Flow characteristics as measured by work-hardening rate are relatively unaffected. Although the ease of basal glide in zone-refined crystals has so far irhibited the appearance of deformation processes permitting c-axis contraction, it is possible that this same ease of basal glide may improve three-dimensional ductility in polycrystalline material by permitting extensive deformation by shear. (auth)

• Research Organization: Nuclear Metals, Inc., West Concord, Mass.
• NSA Number: NSA-17-036299
• OSTI ID: 4651358
• Report Number(s): NMI-TJ-54; CONF-170-1
• Country of Publication: United States
• Language: English

Related Subjects

BERYLLIUM
BRITTLENESS
CRYSTALS
DEFECTS
DEFORMATION
DUCTILITY
FAILURES
IMPURITIES
IRON ALLOYS
LATTICES
MEASURED VALUES
MECHANICAL PROPERTIES
METALS, CERAMICS, AND OTHER MATERIALS
MONOCRYSTALS
QUALITATIVE ANALYSIS
REFINING
SHEAR
SLIP
STRESSES
SURFACES
TEMPERATURE
TEMPERING
TENSILE PROPERTIES
ZONE REFINING
ZONES