msepostdoc-list Seminar Reminder for Qiang Li's Ph.D. Final Exam. Seminar, Monday, June 3, at 9:00 a.m., in ARMS 1028. Exam, same day, at 10:00, in ARMS 2326 " Fabrication, Plasticity, and Thermal Stability of Nanotwinned Al Alloys"
Son, Rosemary E
son39 at purdue.edu
Thu May 30 10:18:28 EDT 2019
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Please consider attending the following:
MATERIALS ENGINEERING
SEMINAR
"Fabrication, Plasticity, and Thermal Stability of Nanotwinned Al Alloys"
By
Qiang Li
Purdue MSE Ph.D. Final Exam
Advisor: Professor Xinghang Zhang
ABSTRACT
Lightweight Al alloys have widespread applications in transportation industry. Applications of Al alloys in harsh environments involving high stress and high temperatures are often hindered because of their inherently low strength and poor performance at high temperatures. The strongest commercial Al alloys have a maximum strength less than 700 MPa. Although ultrafine grained Al alloys prepared by severe plastic deformation have higher strength, they encounter grain growth at moderate temperatures (less than 200 °C).
This thesis focuses on adopting transition metal solutes and non-equilibrium approach to fabricate high-strength, thermally stable nanotwinned Al alloys. To understand the underlying deformation mechanisms of nanotwinned Al alloys, in-situ micromechanical tests, high resolution and analytical transmission microscopy and atomistic simulations were used. Our studies show that nanotwinned supersaturated Al-Fe alloys have a maximum hardness and flow stress of ~ 5.5 GPa and 1.6 GPa, respectively. The apparent directionality of the vertical incoherent twin boundaries renders plastic anisotropy and compression-tension asymmetry in the nanotwinned Al-Fe alloys, revealed by systematic in-situ tensile and compressive micromechanical experiments conducted from both in-plane and out-of-plane directions. Moreover, the nanotwinned Al-Fe alloys experience no apparent softening when tested at 200 °C. When selectively incorporating with one additional solute as stabilizer, the ternary nanotwinned Al alloys can preserve an exceptionally high flow stress, exceeding 2 GPa, prior to precipitous softening at an annealing temperature of > 400 °C. The thesis offers a new perspective to the design of future strong, deformable and thermally stable nanostructured Al alloys.
Date: Monday, June 3, 2019
Time: 9:00 A.M.
Place: ARMS 1028
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- Previous message: msepostdoc-list Seminar Notice for Xing Sun's Ph.D. Final Exam. Seminar, Tuesday, June 11, at 9:00 a.m., in ARMS 1028; Exam same day, at 10:00 a.m., in ARMS 2326. " Controllable Three-Dimensional Strain, Microstructure, Functionalities in Self-Assembled Nanocomposite Th
- Next message: msepostdoc-list Seminar Reminder: NOTE CHANGES for Vikrant Karra's Ph.D. Final Exam, Monday, June 3, at 9:00 a.m., in ARMS 1021. Final will follow at 10:00, in ARMS 2237. "CHARGED INTERFACES: EQUILIBRIUM PROPERTIES, PHASE TRANSITIONS, AND MICROSTRUCTURAL EVOLUTION"
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