Fast transport of cobalt in thorium
Three investigations associated with the fast transport behavior of cobalt in thorium have been conducted. These include (1) a study of a metastable ThCo/sub x/ phase and the solid solubility of cobalt in thorium in dilute thorium-cobalt alloys, (2) a study of the mechanism of fast diffusion of cobalt in thorium using diffusion and internal friction experiments and (3) a study of the thermotransport behavior of cobalt in thorium. A metastable plate phase, having a stoichiometry of about ThCo/sub 0.08/, forms in alloys containing greater than 0.004 at. % Co that are quenched from the single-phase field. Upon aging between 773 and 1073 K the plate phase transforms to rod-like precipitates of the equilibrium Th/sub 7/Co/sub 3/ phase. The solid solubility of cobalt in thorium increases from 0.05 at. % at 1120 K to 0.4 at. % at 1350 K according to the relation, c/sub s/ (at. %) = 7044 exp(/minus/110.5 kJ mol/sup /minus/1//RT). The terminal solid solubility at the eutectic temperature of 1373 K is 0.45 at. %. The activation energy for diffusion of cobalt in ..cap alpha.. thorium is 83.7 kJ/mol whereas that associated with the anelastic relaxation process for cobalt in thorium is 78.0 kJ/mol. The diffusion and internal friction results can be interpreted as supporting either the host-solute diplon mechanism or the interstitial mechanism of fast diffusion. The heat of transport, Q*, for cobalt in thorium was determined by the single-phase steady-state technique and a new technique referred to as the two-phase nonsteady-state technique. 59 refs., 37 figs., 7 tabs.
- Research Organization:
- Ames Lab., IA (USA)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 6363567
- Report Number(s):
- IS-T-1295; ON: DE89007681
- Country of Publication:
- United States
- Language:
- English
Similar Records
Study of the mechanism of fast diffusion of cobalt in thorium by diffusion and internal friction measurements
Studies concerning transport of carbon in niobium, vanadium and vanadium-titanium alloys
Related Subjects
360102 -- Metals & Alloys-- Structure & Phase Studies
360104* -- Metals & Alloys-- Physical Properties
99 GENERAL AND MISCELLANEOUS
990220 -- Computers
Computerized Models
& Computer Programs-- (1987-1989)
ACTINIDE ALLOYS
ACTIVATION ENERGY
ALLOYS
ATOM TRANSPORT
COBALT
COHERENT SCATTERING
COMPUTER CODES
COMPUTER PROGRAM DOCUMENTATION
CRYSTAL STRUCTURE
DIAGRAMS
DIFFRACTION
DIFFUSION
ELEMENTS
ENERGY
ENERGY LEVELS
EUTECTICS
EXCITED STATES
FRICTION
INTERNAL FRICTION
LATTICE PARAMETERS
METALS
METASTABLE STATES
MICROSTRUCTURE
NEUTRAL-PARTICLE TRANSPORT
PHASE DIAGRAMS
QUENCHING
RADIATION TRANSPORT
SCATTERING
SELF-DIFFUSION
SOLUBILITY
T CODES
THORIUM ALLOYS
TRANSITION ELEMENTS
X-RAY DIFFRACTION