About this Abstract |
Meeting |
2021 TMS Annual Meeting & Exhibition
|
Symposium
|
Defect and Phase Transformation Pathway Engineering for Desired Microstructures
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Presentation Title |
Phase Transformation Pathways in High Entropy Alloys or Complex Concentrated Alloys mediated by Defects |
Author(s) |
Sriswaroop Dasari, Bharat Gwalani, Yao-Jen Chang, Deep Choudhuri, Stephane Gorsse, An-Chou Yeh, Rajarshi Banerjee |
On-Site Speaker (Planned) |
Sriswaroop Dasari |
Abstract Scope |
This presentation will demonstrate the strong influence of defects, induced by thermo-mechanical processing, on the phase transformation pathway adopted for second-phase precipitation in high entropy alloys (HEAs) or complex concentrated alloys (CCAs), such as Al0.3CoCrFeNi, Al0.5Co1.5CrFeNi1.5, and Al0.3CoFeNi. A thermo-mechanical processing sequence of homogenization - cold-rolling - solution treatment, followed by a precipitation anneal at a lower temperature, results in homogeneous nanometer scale-ordered L12 (gamma prime-like) precipitates within the face-centered cubic (FCC) matrix. Contrastingly, if the cold-rolled alloys is directly annealed at the precipitation temperature, then the resulting microstructural evolution pathway changes completely, with precipitation of B2 phase, either at the grain boundaries of recrystallized FCC grains and/or on twins and deformation bands within non-recrystallized grains. These experimentally observed variations in transformation pathway have been rationalized via the competition between the thermodynamic driving force and activation barrier for second-phase nucleation in this alloy, coupled with the kinetics of the process. |
Proceedings Inclusion? |
Planned: |