Publication Date
9-12-2017
Department
Ames Laboratory; Materials Science and Engineering
Campus Units
Materials Science and Engineering, Ames Laboratory
Report Number
IS-J 9455
DOI
10.1088/1361-6463/aa85bf
Journal Title
Journal of Physics D: Applied Physics
Volume Number
50
Issue Number
40
First Page
404001
Abstract
The stress-induced martensitic phase transformation of shape memory alloys (SMAs) is the basis for elastocaloric cooling. Here 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 DT 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. 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.
DOE Contract Number(s)
DE-AC02-07CH11358
Language
en
Department of Energy Subject Categories
36 MATERIALS SCIENCE
Publisher
Iowa State University Digital Repository, Ames IA (United States)
