The stress-induced martensitic phase transformation of shape memory alloys (SMAs) is the basis for elastocaloric cooling. In this paper, we employ additive manufacturing to fabricate TiNi SMAs, and demonstrate compressive elastocaloric cooling in the TiNi rods with transformation latent heat as large as 20 J g-1. Adiabatic compression on as-fabricated TiNi displays cooling ΔT as high as -7.5 °C with recoverable superelastic strain up to 5%. Unlike conventional SMAs, additive manufactured TiNi SMAs exhibit linear superelasticity with narrow hysteresis in stress–strain curves under both adiabatic and isothermal conditions. Microstructurally, we find that there are Ti2Ni precipitates typically one micron in size with a large aspect ratio enclosing the TiNi matrix. Finally, a stress transfer mechanism between reversible phase transformation in the TiNi matrix and mechanical deformation in Ti2Ni precipitates is believed to be the origin of the unique superelasticity behavior.
Hou, Huilong, et al. "Elastocaloric cooling of additive manufactured shape memory alloys with large latent heat." Journal of Physics. D, Applied Physics, vol. 50, no. 40, Aug. 2017. https://doi.org/10.1088/1361-6463/aa85bf
@article{osti_1407483,
author = {Hou, Huilong and Simsek, Emrah and Stasak, Drew and Hasan, Naila Al and Qian, Suxin and Ott, Ryan and Cui, Jun and Takeuchi, Ichiro},
title = {Elastocaloric cooling of additive manufactured shape memory alloys with large latent heat},
annote = {The stress-induced martensitic phase transformation of shape memory alloys (SMAs) is the basis for elastocaloric cooling. In this paper, we employ additive manufacturing to fabricate TiNi SMAs, and demonstrate compressive elastocaloric cooling in the TiNi rods with transformation latent heat as large as 20 J g-1. Adiabatic compression on as-fabricated TiNi displays cooling ΔT as high as -7.5 °C with recoverable superelastic strain up to 5%. Unlike conventional SMAs, additive manufactured TiNi SMAs exhibit linear superelasticity with narrow hysteresis in stress–strain curves under both adiabatic and isothermal conditions. Microstructurally, we find that there are Ti2Ni precipitates typically one micron in size with a large aspect ratio enclosing the TiNi matrix. Finally, a stress transfer mechanism between reversible phase transformation in the TiNi matrix and mechanical deformation in Ti2Ni precipitates is believed to be the origin of the unique superelasticity behavior.},
doi = {10.1088/1361-6463/aa85bf},
url = {https://www.osti.gov/biblio/1407483},
journal = {Journal of Physics. D, Applied Physics},
issn = {ISSN 0022-3727},
number = {40},
volume = {50},
place = {United States},
publisher = {IOP Publishing},
year = {2017},
month = {08}}
Ames Lab., Ames, IA (United States); Univ. of Maryland, College Park, MD (United States); Xi'an Jiaotong Univ., Xi'an (China)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Advanced Manufacturing Office (EE-5A); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Advanced Research Projects Agency - Energy (ARPA-E); National Natural Science Foundation of China (NSFC)
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 374, Issue 2074https://doi.org/10.1098/rsta.2015.0309
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Vol. 218, Issue 10https://doi.org/10.1243/0954406042369062