Fast diffusion of cobalt along stationary and moving grain boundaries in niobium
- Univ. Muenster (Germany). Inst. fuer Metallforschung
[sup 57]Co diffusion along grain boundaries (GBs) in high-purity Nb has been studied in the temperature range 823--1,471 K by the serial sectioning technique. As it was not possible to fully stabilize the grain size by any pre-diffusion annealing, part of the GBs could migrate during the diffusion anneals. Using the earlier proposed method, the product P = sD[sub GB][delta] [s being the GB-segregation factor, D[sub GB] the GB-diffusion (GBD) coefficient, [delta] the GB width] for stationary GBs and the velocity V of moving GBs were deduced from the diffusion profiles. The P-values follow an Arrhenius dependence P = (4.84 [sub [minus]2.68][sup =5.99]) [times] 10[sup [minus]13] exp[[minus](149.5 [+-] 7.2) kJ mol[sup [minus]1]/RT] m[sup 3] s[sup [minus]1] and are 4--2 orders of magnitude higher in the measured temperature range than the expected P-values for GB self-diffusion in Nb. This observation is well consistent with the known fact of fast lattice diffusion of Co in Nb and provides evidence for a combined vacancy-interstitial GBD mechanism. From the temperature dependence of V an activation enthalpy of GB motion in Nb H[sub m] [approx equal] 182 kJ mol[sup [minus]1] is estimated.
- OSTI ID:
- 6986851
- Journal Information:
- Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 42:8; ISSN 0956-7151; ISSN AMATEB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104* -- Metals & Alloys-- Physical Properties
ATOM TRANSPORT
BETA DECAY RADIOISOTOPES
COBALT
COBALT 57
COBALT ISOTOPES
DAYS LIVING RADIOISOTOPES
DIFFUSION
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
GRAIN BOUNDARIES
IMPURITIES
INTERMEDIATE MASS NUCLEI
ISOTOPES
METALS
MICROSTRUCTURE
NEUTRAL-PARTICLE TRANSPORT
NIOBIUM
NUCLEI
ODD-EVEN NUCLEI
RADIATION TRANSPORT
RADIOISOTOPES
TRANSITION ELEMENTS