2018 Fiscal Year Research-status Report
Multiscale microstructure engineering and the development of high performance, environmental friendly, low cost and thermally stable half-Heusler thermoelectric materials
| Project/Area Number |
18K04744
|
|---|
| Research Institution | Tokyo Institute of Technology |
|---|
Principal Investigator |
蔡 耀汪 東京工業大学, 物質理工学院, 特任准教授 (80455922)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
木村 好里 東京工業大学, 物質理工学院, 教授 (90262295)
|
|---|
| Project Period (FY) |
2018-04-01 – 2021-03-31
|
| Keywords | interfacial structure / point defects / nanoprecipitates / interphase interface / grain boundary |
|---|
| Outline of Annual Research Achievements |
This proposal aims to develop high performance, environmental friendly, low cost and stable half-Heusler thermoelectric materials based on the introduction of multiscale microstructure in order to recycle waste heat energy from any high temperature source. In order to achieve the goal, much better improvement on fundamental understanding of the multiscale microstructure, which includes microstructure with different length scales, i.e. (a) the atomic point defects, (b) the nanoscopic Heusler nanoprecipitates, (c) the microscopic half-Heusler-half-Heusler domains, and (d) the mesoscopic grain size, of the alloys. At this stage, a series of (Tix,Zr1-x)NiySn half-heusler alloys have been fabricated and we have direct experimental evidence showing that (b) and (c) can be controlled by composition tunning and cyclic heat treatment processes. Most importantly, by increasing surface area density of microstructure(b) and (c), as well as changing their interfacial structure to relatively more diffuse, thermal conducvity of the alloys can be reduced greatly, just like what have expected.
|
| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
As mentioned earlier, we intend to improve the fundamental understanding on formation of multiscale microstructure (i.e. atomic defects, nanoprecipitates, microscopic half-Heusler-half-Heusler domains and the mesoscopic grain size) utilise it to improve thermoelectric properties of half-Heusler alloys. So far, half of the multi-length scale microstructure have been investigated, and direct experimental evidences have been obtained showing how they can be contolled for improving thermoelectric properties of the alloys.
|
| Strategy for Future Research Activity |
In this fiscal year, we continue to investigate and obtain direct experimental evidence showing how the atomic defects and grain size affect thermoelectric propeties of the alloys. Next, alloys containing the all-length-scale microstrutcure will be fabricated and evaluated their effect towards thermoelectric properties of half-Heusler.
|
| Causes of Carryover |
The main reason was because the principal investigator did not use the budget for traveling expenses as the project was still in progress. However, budget for travel expenses for next year will be used to present our findings in major international conference and research publications.
|
