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Title: Elastocaloric cooling of additive manufactured shape memory alloys with large latent heat

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 Ξ”T as high as -7.5 Β°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 Ti 2Ni 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 Ti 2Ni precipitates is believed to be the origin of the unique superelasticity behavior.
Authors:
ORCiD logo [1] ;  [2] ; ORCiD logo [1] ;  [1] ;  [3] ;  [2] ;  [4] ;  [1]
  1. Univ. of Maryland, College Park, MD (United States). Dept. of Materials Science and Engineering
  2. Ames Lab., Ames, IA (United States)
  3. Xi'an Jiaotong Univ., Xi'an (China). Dept. of Refrigeration and Cryogenic Engineering
  4. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States). Dept. of Materials Science and Engineering
Publication Date:
Report Number(s):
IS-J-9455
Journal ID: ISSN 0022-3727; TRN: US1703151
Grant/Contract Number:
AC02-07CH11358; AR0000131; 51606140
Type:
Accepted Manuscript
Journal Name:
Journal of Physics. D, Applied Physics
Additional Journal Information:
Journal Volume: 50; Journal Issue: 40; Journal ID: ISSN 0022-3727
Publisher:
IOP Publishing
Research Org:
Ames Lab., Ames, IA (United States); Univ. of Maryland, College Park, MD (United States); Xi'an Jiaotong Univ., Xi'an (China)
Sponsoring Org:
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 (NNSFC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; additive manufacturing; three-dimensional (3D) printing; shape memory alloys; elastocaloric cooling; latent heat; linear superelasticity
OSTI Identifier:
1407483