Theoretical and experimental determinations of the thermal stability of rare earth oxide particles in rapidly solidified titanium alloys

Journal Article · Wed Jun 01 04:00:00 EDT 1988 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(88)90227-1· OSTI ID:6446255

Konitzer, D G; Lofvander, J P.A.; Court, S A; Fraser, H L ^[1]; Kirchheim, R ^[2]

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1. The Alcoa Technical Center, Alloy Technology Div., Alcoa Center, PA (US)
2. Max-Planck-Institut fur Metallforschung, Institut fur Werkstoffwissenschaften, D-7000 Stuttgart 1 (DE)

The general stability of a dispersion of rare earth oxide particles in Ti has been considered analytically and determined experimentally. Regarding the analytical approach, the solubility product for the formation of erbia from its constituents in a Ti matrix has been calculated using thermodynamic data. This allows the concentration term in the equations for Ostwald ripening to be calculated. This calculation predicts different stabilities for a dispersion of erbia particles depending on whether the alloy contains an excess of Er or oxygen with respect to the formation of the rare earth oxide, Er/sub 2/O/sub 3/. The rate of coarsening is more rapid in samples with an excess of Er compared to those with an excess of oxygen. Both predictions have been verified experimentally by forming the dispersion through heat-treatment at 700/sup 0/C and performing isochronal anneals at higher temperatures to determine the resistance to particle coarsening. Isothermal annealing has been employed to demonstrate that the coarsening involves bulk diffusion, i.e. t/sup 13/ kinetics, and a satisfactory agreement between theoretically derived rate constants and those deduced from experiment has been achieved.

• OSTI ID: 6446255
• Journal Information: Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 36:6; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360104 -- Metals & Alloys-- Physical Properties
ALLOYS
BULK DENSITY
CALCULATION METHODS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
DATA
DATA ANALYSIS
DENSITY
DISPERSION HARDENING
DISPERSIONS
ELEMENTS
EQUATIONS
ERBIUM COMPOUNDS
ERBIUM OXIDES
EXPERIMENTAL DATA
HARDENING
HEAT TREATMENTS
HIGH TEMPERATURE
INFORMATION
ISOTHERMAL PROCESSES
KINETICS
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
REACTION KINETICS
SAMPLING
SOLIDIFICATION
STABILITY
THEORETICAL DATA
THERMODYNAMICS
TITANIUM ALLOYS