Accession Number:

ADA238686

Title:

Fatigue and Fracture of Intermetallic Alloys

Descriptive Note:

Annual rept. 1 Apr 90-31 Mar 91,

Corporate Author:

UNITED TECHNOLOGIES RESEARCH CENTER EAST HARTFORD CT

Report Date:

1991-05-22

Pagination or Media Count:

45.0

Abstract:

Future aircraft gas turbine engines will, most likely, utilize hot- section materials based on systems other than nickel-base superalloys. The identification of new systems has been motivated by the quest for higher combustion temperatures to satisfy the need for greater thrust-to-weight ratios and higher operating efficiencies. Among the potential systems is the broad class of materials known as intermetallics. Research and development has gone into the study of based on the titaniumaluminum system, often with the focus on alloy development through ternary compounds and quaternary additions as well as thermomechanical processing. Three ordered compounds based on this binary system have been investigated to varying degrees titanium alloysaluminum and aluminum alloysBecause of the tendency to form oxidation protective alumina films and its low density Al3Ti has held particular attraction. Despite its oxidation resistance, Al3Ti has remained understudied. Through the addition of certain ternary transition metals, including iron, copper, or nickel, a phase transition can be induced. Being a crystal structure with higher symmetry over the DO22, the L1 sub 2 possesses in mechanical behavior over the ordered tetragonal structure due to the increase in the number of active slip systems and strain compatibility in polycrystals.

Subject Categories:

  • Inorganic Chemistry
  • Properties of Metals and Alloys
  • Fabrication Metallurgy
  • Jet and Gas Turbine Engines

Distribution Statement:

APPROVED FOR PUBLIC RELEASE