Accession Number:

ADA339200

Title:

Processing-Microstructure-Property Relationships in Advanced Intermetallics.

Descriptive Note:

Final rept. 15 Mar 94-31 Dec 97,

Corporate Author:

ROCKWELL INTERNATIONAL CORP THOUSAND OAKS CA SCIENCE CENTER

Personal Author(s):

Report Date:

1998-02-01

Pagination or Media Count:

39.0

Abstract:

Microstructural evolution in near-gamma TiAl alloys during hot working is a complex interaction involving solid state diffusion, dynamic recrystallization and non-uniform strain accommodation. Compression workability testing, coupled with extensive metallographic characterization, has been used to study the evolution of microstructural refinement and chemical homogeneity in three near-gamma TiAl alloys Ti-46Al-0.2B, Ti-48Al-0.2B and Ti-48Al-2Mo-0.2B. Hot working of materials that had undergone an homogenization heat treatment resulted in the breakup of the initial fully lamellar microstructures into isolated islands of lamellae surrounded by fine bands of dynamically recrystallized grains. Using material that had been initially forged to a strain of 0.9 at 1150 deg C with a strain rate of 10exp -3sec, the effect of additional thermal and mechanical working steps was examined. Particular attention was paid to the effect of strain path on the behavior of the remnant lamellar colonies. Strain in the same direction as the first forging had little effect in breaking-up lamellar colonies lying in the plane of the forging while strain applied perpendicular to this direction was more effective in encouraging these features to undergo enough strain to recrystallize.

Subject Categories:

  • Inorganic Chemistry
  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE