LOW TEMPERATURE TENSILE PROPERTIES OF ZONE-REFINED NIOBIUM (COLUMBIUM)
Abstract
Specimens of electron beam zone-refined Nb were subjected to tensile tests in the temperature range from 373 to 4.2 K. Both polycrystalline and single crystalline specimens were tested. 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. 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 t 4.2 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. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1962
- Accession Number
- AD0278051
Entities
People
- J.f. Wellings
- R. Maddin
Organizations
- University of Pennsylvania