Accession Number:

ADA238932

Title:

Plastic Behavior of Al-Li-X Alloys

Descriptive Note:

Final rept. 1 Oct 1987-24 Dec 1990

Corporate Author:

VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE

Personal Author(s):

Report Date:

1991-07-01

Pagination or Media Count:

131.0

Abstract:

The major objectives of this program were to characterize the microstructure, strengthening, deformation and fracture modes of aluminum -- lithium -- X alloys with emphasis on determining the relationships between alloying elements, processing parameters, microstructure, deformation modes and fracture behavior. The following tasks were undertaken. A The literature on Al-Li alloys was reviewed and major problem areas were identified. B A study was conducted on the dependence of the modulus on the various types of precipitates that occur in these age-hardenable alloys. C One major problem area associated with Al-Li alloys has been their low fracture toughness in the short transverse direction. The low fracture toughness and ductility in this direction also appears to cause delamination along the high angle grain boundaries which are parallel to the processing direction. The effects of texture, deformation mode, and precipitate free zones on this phenomenon at both room and cryogenic temperatures were examined. D In order to maximize the strength-fracture toughness properties of Al-Li-X alloys, cold working prior to aging is necessary in order to provide nucleation sites for the strengthening precipitates, to accelerate aging and to minimize the detrimental grain boundary precipitates and associated precipitate free zones. One alternative method of accomplishing the same result is to add trace alloy additions. The role that the trace addition plays on the precipitation in age-hardenable aluminum alloys was examined.

Subject Categories:

  • Properties of Metals and Alloys
  • Fabrication Metallurgy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE