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Effect of composite-like microstructure on superplastic flow and concurrent microstructural evolution in AA8090 Al-Li alloy
W. Fan, , M.C. Chaturvedi
Published in Metallurgical Society of CIM
Volume: 42
Issue: 2
Pages: 219 - 230
The SPF grade sheets of AA8090 Al-Li alloy were observed to possess a composite-like layered microstructure with different microstructures and microtextures near the surface region and in the mid-thickness region in the longitudinal and transverse directions. Tensile specimens representing the microstructures near the surface in the mid-thickness and full thickness of a sheet were deformed under the optimum superplastic condition of strain rate (∈) = 1 × 10-3 s-1 and T = 803 K. The microstructural and microtextural gradient along the sheet thickness were found to result in the highest flow stress in the mid-thickness material which was dominated (60 v%) by brass (110) [12] texture and elongated grains. Grain growth, transformation of elongated grains into equiaxed grains, texture weakening and cavitation occurred during superplastic deformation. Such microstructural evolution in different zones across the thickness direction was found to influence the nature of stress-strain curves to a varying extent in the near surface, mid-thickness and full thickness samples. The mechanical properties and deformation behaviour could be explained by treating the full thickness sheet as a composite of surface and mid-thickness materials.
About the journal
JournalCanadian Metallurgical Quarterly
PublisherMetallurgical Society of CIM