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Combining indentation and diffusion couple techniques for combinatorial discovery of high temperature shape memory alloys

Shastry, VV and Divya, VD and Azeem, MA and Paul, A and Dye, D and Ramamurty, U (2013) Combining indentation and diffusion couple techniques for combinatorial discovery of high temperature shape memory alloys. In: Acta Materialia, 61 (15). pp. 5735-5742.

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Official URL: http://dx.doi.org/10.1016/j.actamat.2013.06.017


We demonstrate the possibility of accelerated identification of potential compositions for high-temperature shape memory alloys (SMAs) through a combinatorial material synthesis and analysis approach, wherein we employ the combination of diffusion couple and indentation techniques. The former was utilized to generate smooth and compositionally graded inter-diffusion zones (IDZs) in the Ni-Ti-Pd ternary alloy system of varying IDZ thickness, depending on the annealing time at high temperature. The IDZs thus produced were then impressed with an indenter with a spherical tip so as to inscribe a predetermined indentation strain. Subsequent annealing of the indented samples at various elevated temperatures, T-a, ranging between 150 and 550 degrees C allows for partial to full relaxation of the strain imposed due to the shape memory effect. If T-a is above the austenite finish temperature, A(f), the relaxation will be complete. By measuring the depth recovery, which serves as a proxy for the shape recovery characteristic of the SMA, a three-dimensional map in the recovery temperature composition space is constructed. A comparison of the published Af data for different compositions with the Ta data shows good agreement when the depth recovery is between 70% and 80%, indicating that the methodology proposed in this paper can be utilized for the identification of promising compositions. Advantages and further possibilities of this methodology are discussed.

Item Type: Journal Article
Publication: Acta Materialia
Publisher: Elsevier Science
Additional Information: Copyright of this article belongs to Elsevier Science.
Keywords: Shape Memory Alloys; High Temperature; Indentation; Austenite to Martensite Phase Transformation; Combinatorial Methods
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 10 Oct 2013 05:23
Last Modified: 10 Oct 2013 05:23
URI: http://eprints.iisc.ac.in/id/eprint/47477

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