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)

Included in

Metallurgy Commons

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