Accession Number : ADA192217

Title :   Optimizing Superplastic Response in Lithium Containing Aluminum-Magnesium Alloys.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Munro, Ian G

PDF Url : ADA192217

Report Date : Dec 1987

Pagination or Media Count : 93

Abstract : Four lithium containing Al-Mg-Zr alloys, containing 6-8 wt. pct. Mg, 0.5-2 wt. pct. Li, and 0.15-0.25 wt. pct. Zr. were studied with a view to maximizing superplastic ductilities. Differential scanning calorimetry was employed to assist in the characterization of the microstructures and to determine the solvi of the constituent second phases. These data were used to aid in the choice of thermomechanical processing parameters previously applied to Al-Mg alloys containing 10 wt. pct. magnesium. The superplastic response of the alloys was evaluated over a range of temperatures (275 C to 350 C) and a range of strain rates (10 to the minus 5 power 0.1 sec-1). Elongations in excess of 1000% at 300 C and .01.7 sec-1 strain rate were obtained in a Al-8Mg-1Li-0.15Zr (wt. pct.) alloy. Transmission electron microscope investigations of the microstructure before and after superplastic deformation revealed that the volume fraction of second phase was predominantly responsible for structural stability. Keywords: Aluminum magnesium lithium, Superplastic response, Superplasticity, Thermomechanical processing, Theses.

Descriptors :   *ALUMINUM ALLOYS, *MAGNESIUM ALLOYS, *PLASTIC PROPERTIES, ALUMINUM, CALORIMETRY, ELECTRON MICROSCOPES, ELONGATION, LITHIUM, MAGNESIUM, MICROSTRUCTURE, PLASTIC DEFORMATION, PROCESSING, SCANNING, STABILITY, STRAIN RATE, STRUCTURAL PROPERTIES, THERMOMECHANICS, THESES, TRANSMITTANCE, DUCTILITY

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE