LOW TEMPERATURE TENSILE PROPERTIES OF ZONE-REFINED NIOBIUM (COLUMBIUM)

Technical Report · Mon Jan 01 04:00:00 EST 1962

OSTI ID:4826231

Wellings, J F; Maddin, R

Specimens of electron beam zone-refined niobium were subjected to tensile tests in the temperature range from 373 to 4.2 deg K. Both polycrystalline and single crystalline specimens were tested at a constant strain rate of 3.3 x 10/sup -4/ seconds/sup -1/. Specimens were either deformed to fracture or the temperature was changed during deformation to measure the reversible flow stress. The quantity of impurities remaining in the zone-refined material was ascertained by chemical analyses and the results were checked by resistivity measurements. It was found that a significant amount of zone- refining took place even at the relatively high rates of zone travel used (2mm/ min.). Twinning was observed in all specimens tested at 4.2 deg K. No discontinuous yield points were observed in these tests indicating that this phenomenon is dependent upon impurity content. An increased impurity level resulted in a lowering of the yield and flow stresses without an appreciable change in the temperature dependence. This indicates that a lattice frictional stress is the possible mechanism responsible for the temperature dependence of the yield and flow stresses. (auth)

• Research Organization: Pennsylvania. Univ., Philadelphia. School of Metallurgical Engineering
• NSA Number: NSA-16-022593
• OSTI ID: 4826231
• Report Number(s): NP-11795
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CRYSTALS
DEFORMATION
ELECTRIC CONDUCTIVITY
ELECTRON BEAMS
FAILURES
FRICTION
IMPURITIES
LATTICES
LOW TEMPERATURE
MATERIALS TESTING
MEASURED VALUES
METALS, CERAMICS, AND OTHER MATERIALS
MONOCRYSTALS
NIOBIUM
QUALITATIVE ANALYSIS
REFINING
STRESSES
TEMPERATURE
TENSILE PROPERTIES
TWINNING