Low-temperature mechanical properties of superconducting radio frequency cavity materials

Thak Sang Byun, Sang Ho Kim, John Mammosser

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Low-temperature mechanical behaviors have been investigated for the constituent materials of superconducting radio frequency cavities. Test materials consist of small grain Nb, single crystal Nb, large grain Nb (bicrystal), Ti45Nb-Nb weld joint (e-beam welded), and Ti-316L bimetal joint (explosion welded). The strength of all test metals displayed strong temperature dependence and the Ti-316L bimetal showed the highest strength and lowest ductility among the test materials. The fracture toughness of the small grain Nb metals decreased with decreasing test temperature and reached the lower shelf values (30-40 MPa √m) at or above 173 K. The Ti45Nb base and Ti45Nb-Nb weld metals showed much higher fracture toughness than the small grain Nb. An extrapolation and comparison with existing data showed that the fracture toughness of the small grain Nb metals at 4 K was expected to be similar to those at 173 and 77 K. The results from optical photography at a low magnification and fractography by a scanning electron microscope were consistent with corresponding mechanical properties.

Original languageEnglish
Pages (from-to)420-426
Number of pages7
JournalJournal of Nuclear Materials
Volume392
Issue number3
DOIs
StatePublished - Aug 1 2009

Funding

The study was sponsored by US Department of Energy, Offices of Basic Energy Science, under Contract DE-AC05-00OR22725 with UT-Battelle, LLC. The authors thank E. Manischmudt and A.M. Williams for their efforts for DCT fracture testing and SEM fractography. The authors also express special thanks to Drs Isidoro E. Campisi and David A. McClintock for their thorough reviews and thoughtful comments.

FundersFunder number
Basic Energy ScienceDE-AC05-00OR22725
US Department of Energy

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