Accession Number : ADA193029

Title :   Analysis of Grain Refinement and Superplasticity in Aluminum-Magnesium Alloys.

Descriptive Note : Doctoral thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Abou-Salama, Ahmed A

PDF Url : ADA193029

Report Date : Dec 1987

Pagination or Media Count : 167

Abstract : Previous research had demonstrated superplastic behavior in aluminum-magnesium alloys of high magnesium content to result from deformation processing to an initially non recrystallized condition. Analysis here of those data has demonstrated that such a result may be understood in terms of constitutive equations developed for fine-grained materials and that the constitutive equations are applicable to materials achieving grain boundary misorientations in the range of only 2 to 7 by a process of continuous recrystallization. The constitutive equations provide a basis for analysis of anomalous temperature dependence of the strength and of the activation energy for plastic deformation seen as well in this work. A study of the separate effects of processing variables has lead to a model for continuous recrystallization during deformation processing. This model considers recovery of dislocations to sub-boundaries to be the critical step in this process. Application of this model to development of advanced aluminum alloys for air frame structural applications will result in increased weight savings by such processing methods. Theses Keywords: Superplasticity; Aluminum magnesium alloys; Thermomechanical processing; Microstructural evolution; Continuous recrystallization; Microstructural instability; Grain growth.

Descriptors :   *ALUMINUM ALLOYS, *GRAIN STRUCTURES(METALLURGY), *MAGNESIUM ALLOYS, *PLASTIC PROPERTIES, ACTIVATION ENERGY, AIRFRAMES, ANOMALIES, DEFORMATION, DISLOCATIONS, EQUATIONS, EVOLUTION(GENERAL), FINE GRAINED MATERIALS, GRAIN BOUNDARIES, GRAIN GROWTH, MAGNESIUM, METHODOLOGY, MICROSTRUCTURE, PLASTIC DEFORMATION, PROCESSING, RECRYSTALLIZATION, REFINING, STABILITY, STRUCTURAL PROPERTIES, TEMPERATURE, THERMOMECHANICS, THESES, VARIABLES, WEIGHT REDUCTION

Subject Categories : Properties of Metals and Alloys
      Fabrication Metallurgy

Distribution Statement : APPROVED FOR PUBLIC RELEASE