The Use of Backscattered Electron Imaging Mode to Assess the Effect of Fine Dispersions on Development of Superplastic Microstructure in Al-Mg Alloys
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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Microstructural evolution during thermomechanical processing of several Al-Mg alloys was studied using backscattered orientation contrast imaging in the scanning electron microscope. The microstructural evolution in A1-8Mg-0.1Zr was characterized in three phases a in the initial stages, precipitation occurred on prior boundaries and microbands were observed in the grain interiors b during intermediate stages, higher order microbands were observed and precipitates formed throughout the microstructure on both lower- and higher-order microbands c in the final stages, equiaxed regions appeared around larger particles suggesting particle stimulated nucleation of recrystallization. A higher Mg-content alloy A1-10Mg0.1Zr was compared at two stages and seen to provide a greater volume fraction of similar sized precipitate. A finer recrystallized microstructure and greater superplastic response was observed in the Al-10Mg-0.1Zr alloy.
- Properties of Metals and Alloys