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Title: Deformation mechanisms, defects, heat treatment, and thermal conductivity in large grain niobium

The physical and mechanical metallurgy underlying fabrication of large grain cavities for superconducting radio frequency accelerators is summarized, based on research of 1) grain orientations in ingots, 2) a metallurgical assessment of processing a large grain single cell cavity and a tube, 3) assessment of slip behavior of single crystal tensile samples extracted from a high purity ingot slice before and after annealing at 800 °C / 2 h, 4) development of crystal plasticity models based upon the single crystal experiments, and 5) assessment of how thermal conductivity is affected by strain, heat treatment, and exposure to hydrogen. Because of the large grains, the plastic anisotropy of deformation is exaggerated, and heterogeneous strains and localized defects are present to a much greater degree than expected in polycrystalline material, making it highly desirable to computationally anticipate potential forming problems before manufacturing cavities.
Authors:
; ;  [1] ;  [2] ;  [3] ; ;  [2] ; ;  [4] ;  [5] ;  [6] ;  [7]
  1. Chemical Engineering and Materials Science, Michigan State University, East Lansing MI 48824-1226, US (United States)
  2. Mechanical Engineering, Michigan State University, East Lansing MI 48824-1226, US (United States)
  3. (United States)
  4. Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606, US (United States)
  5. Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210, US (United States)
  6. Chemical and Materials Engineering, University of Nevada at Reno, Reno NV, 89557, US (United States)
  7. Facility for Rare Isotope Beams, Michigan State University, East Lansing MI 48824-1226, US (United States)
Publication Date:
OSTI Identifier:
22492683
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1687; Journal Issue: 1; Conference: Ingot niobium summary workshop, Newport News, VA (United States), 4 Dec 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ACCELERATORS; ANISOTROPY; ANNEALING; CAVITIES; DEFECTS; DEFORMATION; GRAIN ORIENTATION; METALLURGY; MONOCRYSTALS; NIOBIUM; PLASTICITY; POLYCRYSTALS; RADIOWAVE RADIATION; RF SYSTEMS; STRAINS; SUPERCONDUCTING CAVITY RESONATORS; SUPERCONDUCTING CYCLOTRONS; TEMPERATURE RANGE 0400-1000 K; THERMAL CONDUCTIVITY; TUBES