The effect of thermal exposure on microstructure stability and creep resistance of a two-phase TiAl/Ti[sub 3]Al lamellar alloy

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

OSTI ID:6824164

Bartholomeusz, M F ^[1]; Wert, J A ^[2]

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1. Reynolds Metals Co., Richmond, VA (United States)
2. Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science and Engineering

During annealing of a two-phase TiAl/Ti[sub 3]Al lamellar alloy at 1,273 and 1,323 K, the lamellar microstructure evolves into a coarse, globular microstructure. For short annealing times (less than about 1,000 hours), microstructural evolution occurs predominantly by intrapacket termination migration coarsening. For longer annealing times, cylinderization and conventional Ostwald ripening coarsening mechanisms are observed. The activation energy for the rate-controlling diffusion process governing intrapacket termination migration coarsening of the lamellar microstructure was determined to be 215 kJ/mol. Compression creep tests reveal that the minimum creep rate and primary creep strain of the lamellar alloy increase with increasing prior annealing time. Furthermore, in contrast to the lamellar microstructure, the globular microstructure is not susceptible to deformation-induced spheriodization during compression creep testing. Modeling demonstrates that the increase of the minimum creep rate and primary creep strain as a consequence of annealing of the lamellar alloy can be accounted for by consideration of two factors: the decrease in the work-hardening rate of the lamellar alloy in response to the overall decrease in interphase interfacial area and the decreased mechanical strengthening effect associated with transformation from a lamellar to a globular microstructure.

• OSTI ID: 6824164
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 25:11; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
ANNEALING
CREEP
DATA
EXPERIMENTAL DATA
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HEAT TREATMENTS
INFORMATION
INTERMETALLIC COMPOUNDS
MATERIALS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NUMERICAL DATA
TITANIUM ALLOYS