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Instrumented micro-indentation of NiTi shape-memory alloys

Publication ,  Journal Article
Gall, K; Juntunen, K; Maier, HJ; Sehitoglu, H; Chumlyakov, YI
Published in: Acta Materialia
September 20, 2001

We study the instrumented Vickers micro-indentation of single-crystal Ti-50.9 at% Ni shape-memory alloys with systematically varied surface normal orientations ([100], [210], [111] and [221]) and Ti3Ni4 precipitate sizes (0 nm, 10 nm, 50 nm, 100 nm, 300 nm and 500 nm). Based on transmission electron microscopy observations, indentation of solutionized NiTi induces inelastic deformation via dislocation activity and a stress-induced martensitic transformation. The room-temperature hardness, Hv, and recoverable energy, Er, of NiTi are shown to be a maximum for very small precipitate sizes, decrease for intermediate precipitate sizes, and increase for large precipitate sizes. The maximization of Hv and Er at small precipitate sizes (10 nm) is attributed to the relatively high resistance to both dislocation motion and a recoverable stress-induced martensitic transformation. The decreases in Hv and Er at intermediate precipitate sizes (50-300 nm) are attri buted to a decrease in the resistance to dislocation motion and a measured increase in the transformation temperatures with respect to the indentation temperature. The increases in Hv and Er at large precipitate sizes (500 nm) are attributed solely to measured decreases in the transformation temperatures with respect to the indentation temperature, since the resistance to dislocation motion remains constant as the precipitates grow from 300 nm to 500 nm. For nearly all heat treatments, the [100] and [221] surfaces demonstrate the highest and lowest values of Hv and Er, respectively, an effect attributed primarily to orientation of favorable slip systems. © 2001 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.

Duke Scholars

Published In

Acta Materialia

DOI

ISSN

1359-6454

Publication Date

September 20, 2001

Volume

49

Issue

16

Start / End Page

3205 / 3217

Related Subject Headings

  • Materials
  • 5104 Condensed matter physics
  • 4017 Mechanical engineering
  • 4016 Materials engineering
  • 0913 Mechanical Engineering
  • 0912 Materials Engineering
  • 0204 Condensed Matter Physics
 

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Gall, K., Juntunen, K., Maier, H. J., Sehitoglu, H., & Chumlyakov, Y. I. (2001). Instrumented micro-indentation of NiTi shape-memory alloys. Acta Materialia, 49(16), 3205–3217. https://doi.org/10.1016/S1359-6454(01)00223-3
Gall, K., K. Juntunen, H. J. Maier, H. Sehitoglu, and Y. I. Chumlyakov. “Instrumented micro-indentation of NiTi shape-memory alloys.” Acta Materialia 49, no. 16 (September 20, 2001): 3205–17. https://doi.org/10.1016/S1359-6454(01)00223-3.
Gall K, Juntunen K, Maier HJ, Sehitoglu H, Chumlyakov YI. Instrumented micro-indentation of NiTi shape-memory alloys. Acta Materialia. 2001 Sep 20;49(16):3205–17.
Gall, K., et al. “Instrumented micro-indentation of NiTi shape-memory alloys.” Acta Materialia, vol. 49, no. 16, Sept. 2001, pp. 3205–17. Scopus, doi:10.1016/S1359-6454(01)00223-3.
Gall K, Juntunen K, Maier HJ, Sehitoglu H, Chumlyakov YI. Instrumented micro-indentation of NiTi shape-memory alloys. Acta Materialia. 2001 Sep 20;49(16):3205–3217.
Journal cover image

Published In

Acta Materialia

DOI

ISSN

1359-6454

Publication Date

September 20, 2001

Volume

49

Issue

16

Start / End Page

3205 / 3217

Related Subject Headings

  • Materials
  • 5104 Condensed matter physics
  • 4017 Mechanical engineering
  • 4016 Materials engineering
  • 0913 Mechanical Engineering
  • 0912 Materials Engineering
  • 0204 Condensed Matter Physics