- Home
- Events and Seminars
- 109-2-senimar 4/15
109-2-senimar 4/15
2021.04.12
Speaker: Dr.Chien-Lung Liang
Title:Developing Athermal Electron Wind Force for the Microstructure and Properties Manipulation of Metallic Materials
Abstract:
Current-assisted mass transport induced the migration of atoms which was called “electromigration.” The unique electron wind force served as the driving force for inducing the generation of defects (vacancy and dislocation) and resulting in lattice strain accumulation in metallic materials. Electromigration is an inevitable phenomenon that will cause the failure occurrence in metallic interconnects in electronic devices after a long-term current stressing. However, we introduced herein a material treatment approach that takes advantage of the “athermal” electron wind force that can produce high-density dislocations in metals and the accompanying “thermal” Joule heating effect for inducing the subsequent recrystallization process. The interaction between dislocations and electron wind, the fundamental of the current-assisted treatment or “electro-treatment,” was the basic theory applied for the microstructure and properties manipulation. We observed the high-density dislocation generation through the HR-TEM lattice image and large plastic strain accumulation through the in situ synchrotron XRD in a variety of metallic systems. These phenomena induced by direct current stressing, referred to “electrodisruption,” can be expected to contribute to the work hardening and the subsequent dynamic recrystallization occurrences. Grain refining, as characterized by the EBSD technique, also contributed to the strengthening of materials after current stressing. Electro-treatment as proposed is expected to be a potential approach with high-efficiency and low-energy consumption features for replacing post-working heat treatment of metals.
Speaker: Dr.Pai-Chun Wei
Title:Recent Advances in Thermoelectrics
Abstract:
As renewable energy issues are drawing more attention than ever, the search for more efficient ways to harvest plentiful waste heat has been intensified. With the ability to perform the mutual transformation between thermal and electricity, thermoelectric (TE) power devices have been considered as crucial alternative energy technology and a cure for greenhouse emissions. Thanks to the discovery of new materials and innovating engineering strategies, the figure of merit of TE materials, zT, has been pronouncedly increased in recent years. Various vital concepts and theories have also been proposed to elucidate the extraordinary TE performance. This talk will first outline the common structural features of TE materials, along with their unusual electron and phonon transport behaviors that well satisfy the concept of“electron-crystal phonon-glass.” Next, the novel strategies for further improving their TE performance are highlighted. The recent progress achieved in the TE field is then summarized, with an emphasis on their diverse crystal structures, common characteristics, and unique transport properties.
Time:4/15 3:10pm
Venue:At the A1302 classroom on the 3rd floor overhead bridge corridor between MSE and Resource Engineering Building .
Title:Developing Athermal Electron Wind Force for the Microstructure and Properties Manipulation of Metallic Materials
Abstract:
Current-assisted mass transport induced the migration of atoms which was called “electromigration.” The unique electron wind force served as the driving force for inducing the generation of defects (vacancy and dislocation) and resulting in lattice strain accumulation in metallic materials. Electromigration is an inevitable phenomenon that will cause the failure occurrence in metallic interconnects in electronic devices after a long-term current stressing. However, we introduced herein a material treatment approach that takes advantage of the “athermal” electron wind force that can produce high-density dislocations in metals and the accompanying “thermal” Joule heating effect for inducing the subsequent recrystallization process. The interaction between dislocations and electron wind, the fundamental of the current-assisted treatment or “electro-treatment,” was the basic theory applied for the microstructure and properties manipulation. We observed the high-density dislocation generation through the HR-TEM lattice image and large plastic strain accumulation through the in situ synchrotron XRD in a variety of metallic systems. These phenomena induced by direct current stressing, referred to “electrodisruption,” can be expected to contribute to the work hardening and the subsequent dynamic recrystallization occurrences. Grain refining, as characterized by the EBSD technique, also contributed to the strengthening of materials after current stressing. Electro-treatment as proposed is expected to be a potential approach with high-efficiency and low-energy consumption features for replacing post-working heat treatment of metals.
Speaker: Dr.Pai-Chun Wei
Title:Recent Advances in Thermoelectrics
Abstract:
As renewable energy issues are drawing more attention than ever, the search for more efficient ways to harvest plentiful waste heat has been intensified. With the ability to perform the mutual transformation between thermal and electricity, thermoelectric (TE) power devices have been considered as crucial alternative energy technology and a cure for greenhouse emissions. Thanks to the discovery of new materials and innovating engineering strategies, the figure of merit of TE materials, zT, has been pronouncedly increased in recent years. Various vital concepts and theories have also been proposed to elucidate the extraordinary TE performance. This talk will first outline the common structural features of TE materials, along with their unusual electron and phonon transport behaviors that well satisfy the concept of“electron-crystal phonon-glass.” Next, the novel strategies for further improving their TE performance are highlighted. The recent progress achieved in the TE field is then summarized, with an emphasis on their diverse crystal structures, common characteristics, and unique transport properties.
Time:4/15 3:10pm
Venue:At the A1302 classroom on the 3rd floor overhead bridge corridor between MSE and Resource Engineering Building .