2018 Fiscal Year Annual Research Report
Elastocaloric effect at small scales towards micro-cooling device
| Project/Area Number |
18J11979
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| Research Institution | Tohoku University |
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Principal Investigator |
許 勝 東北大学, 工学研究科, 特別研究員(DC2)
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| Project Period (FY) |
2018-04-25 – 2020-03-31
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| Keywords | Cu-Al-Mn / shape memory alloy / elatocaloric effect / elasticity |
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| Outline of Annual Research Achievements |
The research aims to investigate the elastocaloric effect, superelastic behavior at small scales and the corresponding functional fatigue for Cu-Al-Mn shape memory alloys, as to offer a basic guidance for the design of solid-state micro-cooling devices in the aspect of materials. This year, the crystal orientation dependence of elastocaloric effect at the bulk scale was investigated. The mechanical tests at the small scale were also carried out.
Bulk single-crystalline Cu-Al-Mn samples with different orientations were prepared by abnormal grain growth. The temperature change upon superelasticity was measured by thermocouples during tensile tests. The adiabatic temperature change was found to be almost independent of crystal orientation and reach about 14K for all samples. The stress hysteresis for different orientated samples varied a little and was very small (~30MPa), so the dissipated energy is considered to be small. The orientation independent elastocaloric effect is then ascribed to the constant entropy change involving the full martensitic transformation and the small dissipated energy.
The superelasticity at the small scale was not observed by micro-tension tests. The correct stress-strain curves could not be obtained caused by the insufficient fixation of the small-scale tensile samples, indicating that the test methods should be improved.
Accompanying with alloy design, the elastic behavior of the alloys was investigated. Anomalous elasticity was confirmed for Cu-Al-Mn alloys, including the anomaly in Poisson's ratio, elastic strain, and Young's modulus, and so on.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The elastocaloric effect in bulk state was successfully determined. The micro-tension test is in progress. Anomaloy in elasticity was experimentally confirmed.
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| Strategy for Future Research Activity |
In the next stage, the test methods for micro-tension will be improved to obtain the correct stress-strain curves. The superelasticity at small scales and its functional fatigue will be investigated.
The anomaly in elasticity will be studied in details, including the Poisson’s ratio, elastic strain, and Young’s modulus, etc. To investigate the microstructural change during elastic deformation at the atom scale, in-situ XRD, in-situ TEM and in-situ neutron diffraction will be carried out.
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Research Products
(4 results)
