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Author Ricker, R. E. ♦ Pitchure, D. J. ♦ Myneni, G. R.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ ENGINEERING ♦ ACCELERATORS ♦ CAVITIES ♦ DATA COVARIANCES ♦ FAILURES ♦ HYDROGEN ♦ IMPURITIES ♦ INDICATORS ♦ INTERSTITIALS ♦ MECHANICAL TESTS ♦ MONOCRYSTALS ♦ NIOBIUM ♦ PEAKS ♦ POLYCRYSTALS ♦ STRAIN RATE ♦ SUPERCONDUCTING CAVITY RESONATORS ♦ TENSILE PROPERTIES ♦ YIELD STRENGTH
Abstract A preliminary investigation was conducted into the feasibility of using simple mechanical properties experiments to evaluate interstitial impurity uptake from processing environments. Two types of tests were examined: tensile tests and complex modulus measurements using a dynamic mechanical analyzer (DMA). For the tensile tests, samples were cut from a single crystal of niobium, with the same orientation, and then prepared following different procedures. Significant differences were observed during tensile tests, with yielding strength and strain-to-failure clearly related to interstitial uptake. When the strain rate was reduced by an order of magnitude, the strain-to-failure was reduced by 18 % indicating that interstitial hydrogen is responsible for this behavior. For the complex modulus measurement, polycrystalline samples from different locations of two different ingots were examined at a frequency of 1.0 Hz while the temperature was increased at the rate of 1.0 °C per minute. Anaelastic peaks were found for C, N, and O in all samples, but the lower limit of the system did not allow for detection of a peak for H. It is concluded that mechanical properties could be developed as a measurement tool to guide the development of processing methods for producing reduced interstitial content material, but additional research, and uncertainty analysis, is required for these tools to be reliable in this application.
ISSN 0094243X
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-12-04
Publisher Place United States
Volume Number 1687
Issue Number 1


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