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The activation energy for creep of columbium /niobium/.The activation energy for creep of nominally pure columbium (niobium) was determined in the temperature range from 0.4 to 0.75 T sub M by measuring strain rate changes induced by temperature shifts at constant stress. A peak in the activation energy vs temperature curve was found with a maximum value of 160 kcal/mole. A pretest heat treatment of 3000 F for 30 min resulted in even higher values of activation energy (greater than 600 kcal/mole) in this temperature range. The activation energy for the heat-treated columbium (Nb) could not be determined near 0.5 T sub M because of unusual creep curves involving negligible steady-state creep rates and failure at less than 5% creep strain. It is suggested that the anomalous activation energy values and the unusual creep behavior in this temperature range are caused by dynamic strain aging involving substitutional atom impurities and that this type of strain aging may be in part responsible for the scatter in previously reported values of activation energy for creep of columbium (Nb) near 0.5 T sub M.
Document ID
19730057778
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Klein, M. J.
Gulden, M. E.
(International Harvester Co. San Diego, Calif., United States)
Date Acquired
August 7, 2013
Publication Date
September 1, 1973
Publication Information
Publication: Metallurgical Transactions
Volume: 4
Subject Category
Materials, Metallic
Accession Number
73A42580
Distribution Limits
Public
Copyright
Other

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