Accession Number:

ADA282971

Title:

Fundamental Concepts Relating Local Atomic Arrangements, Deformation, and Fracture of Intermetallic Alloys

Descriptive Note:

Final rept. Apr 1993-31 Mar 1994

Corporate Author:

VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s):

Report Date:

1994-04-01

Pagination or Media Count:

120.0

Abstract:

The creep resistance of a TiAlTi3Al alloy with a lamellar microstructure has been previously found to be superior to the creep resistance of single-phase TiAl and Ti3Al alloys with compositions close to the compositions of the individual phases in the lamellar alloy. The objectives of the present research project were to identify the origin of the enhanced creep resistance of the TiAlTi3Al lamellar alloy, to formulate a model capable of predicting the creep strength of the TiAlTi3Al lamellar alloy, and to evaluate the effect of thermal exposure on the creep strength of the TiAlTi3Al lamellar alloy. The results, analyses and interpretations described in this report show that the enhanced creep resistance of the TiAlTi3Al lamellar alloy arises from the lamellar morphology of the TiAl and Ti3Al phases. The lamellar morphology provides a large interphase interfacial area per unit volume, which is proposed to introduce a high density of dislocation sources. The high density of dislocation sources is thought to increase the work hardening rate of the lamellar alloy relative to the individual single phase alloys an effect which contributes the small primary creep strain and low secondary creep rate exhibited by the lamellar alloy. When the increased work hardening rate is accounted for in the constitutive equations for creep of the individual TiAl and Ti3Al phases, an analytical model formulated for creep of discontinuous, lamellar-reinforced composites can be used to predict the creep strength of the TiAlTi3Al lamellar alloy from the creep properties of the single phase alloys. TiAl, Ti3Al, Intermetallic, Creep, Lamellar composite, Constitute model, Coarsening.

Subject Categories:

  • Inorganic Chemistry
  • Properties of Metals and Alloys
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE