Superplastic properties of an Al-2. 4Mg-1. 8Li-0. 5Sc alloy
- Lawrence Berkeley Lab., CA (United States). Center for Advanced Materials
This paper reports that there is a need in the aerospace industry for structural, superplastic aluminum alloys that are formable at strain-rates greater than 10{sup {minus}3}s{sup {minus}1} in order for the economic benefits of superplastic forming to be realized. The standard, structural, superplastic aluminum alloy in the aerospace industry is 7475, which has an optimum forming strain-rate near 10{sup {minus}4} s{sup {minus}1}. Thus, research has been focused on modifying the microstructures of wrought Al-Li alloys such as 2090 and 8090 into superplastically formable (SPF) microstructures with improved properties, but the results have not been completely successful. Superplastic alloys with high strengths have been produced from the Al-Mg-Sc system. These alloys are strengthened by thermomechanical processing which precipitates small, coherent Al{sub 3}Sc particles and increases the dislocation density of the material. The Mg is in solid solution and improves the work hardening capability of these alloys. Because superplastic forming is carried out at relatively high temperatures, recovery processes eliminate the dislocation strengthening resulting from the rolling and overage the precipitates. Lithium provides the most promising choice since it forms the ordered coherent precipitate {delta} (Al{sub 3}Li), lowers the density, and increases the stiffness of aluminum alloys.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5296163
- Journal Information:
- Scripta Metallurgica; (United States), Journal Name: Scripta Metallurgica; (United States) Vol. 25:1; ISSN 0036-9748; ISSN SCRMB
- Country of Publication:
- United States
- Language:
- English
Similar Records
Superplasticity in aerospace II; Proceedings of the Symposium, 119th Annual Meeting of the Metallurgical Society, Anaheim, CA, Feb. 19-22, 1990
Superplasticity in aerospace; Proceedings of the Topical Symposium, Phoenix, AZ, Jan. 25-28, 1988
Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
AEROSPACE INDUSTRY
ALLOYS
ALUMINIUM ALLOYS
CRYSTAL STRUCTURE
DENSITY
HARDENING
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HIGH TEMPERATURE
INDUSTRY
LITHIUM ALLOYS
MAGNESIUM ALLOYS
MATERIALS
MATERIALS TESTING
MECHANICAL PROPERTIES
MICROSTRUCTURE
PHYSICAL PROPERTIES
RESEARCH PROGRAMS
SCANDIUM ALLOYS
STRAIN HARDENING
TENSILE PROPERTIES
TESTING