|Title||Microstructural evolution of TiAl-based alloys deformed by high-pressure torsion|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Cao, GH, Russell, AM, Oertel, CG, Skrotzki, W|
|Type of Article||Article|
|Keywords||creep-behavior, Dislocations, electron-microscopy, gamma, High-pressure torsion, high-strain torsion, lamellar structure, mechanisms, Microstructure, nanocrystalline structure, phase-transformation, severe plastic-deformation, Titanium aluminides, transmission, Transmission electron microscopy (TEM)|
gamma transformation induced by torsion is a diffusional process, and the gamma-phase growth occurs by a diffusion-controlled step mechanism. The grain size produced by HPT does not change significantly compared to the initial microstructure, which is at the micrometer-scale. During torsion a steady-state stage was achieved, and the power law stress exponents and activation energies were measured to be 1.77 and 1.42, and 3.45 and 3.37 eV for torsion deformed at 900 and 1000 degrees C, respectively. It is concluded that torsion deformation occurred by superplastic flow through grain-boundary sliding accommodated by dislocation motion. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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