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The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi: Part I- Aged microstructure and micro-mechanical modeling

Publication ,  Journal Article
Gall, K; Sehitoglu, H; Chumlyakov, YI; Kireeva, IV; Maier, HJ
Published in: Journal of Engineering Materials and Technology, Transactions of the ASME
January 1, 1999

Transmission electron microscopy is used to determine the microstructures of a Ti- 50.8 at% Ni alloy given different aging treatments. Two different peak-aging treatments are shown to result in disk shaped semi-coherent Ti3Ni4 precipitates with a diameter ranging from 50 nm to 200 nm depending on the aging temperature. In the peak-aged materials, strong strain fields are clearly visible on TEM micrographs. An Eshelby based model is used to predict the local stress fields due to the differences in the lattice parameters of the precipitates and surrounding matrix. The position dependent local stress fields are then resolved onto the 24 different martensite correspondence variant pairs (CVP’s). It is further demonstrated that due to the unique orientation relationship that exists between the precipitate variants and the martensite CVP’s, the local resolved shear stresses are extremely large on some CVP’s and negligible on others. When the Ni rich NiTi is over-aged, it is found that the precipitates coarsen to approximately 1000 nm, they become in-coherent, and the local stress fields disappear. It is also determined that after over-aging the average composition of the matrix drops from 50.8 at% Ni to approximately 50.4 at% Ni. In a subsequent paper (part II) the results here are used to explain the dependence of the critical transformation stress levels and martensite start temperatures on the aging treatment. © 1999 by ASME.

Duke Scholars

Published In

Journal of Engineering Materials and Technology, Transactions of the ASME

DOI

EISSN

1528-8889

ISSN

0094-4289

Publication Date

January 1, 1999

Volume

121

Issue

1

Start / End Page

19 / 27

Related Subject Headings

  • Materials
  • 4017 Mechanical engineering
  • 4016 Materials engineering
  • 0913 Mechanical Engineering
  • 0912 Materials Engineering
  • 0910 Manufacturing Engineering
 

Citation

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ICMJE
MLA
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Gall, K., Sehitoglu, H., Chumlyakov, Y. I., Kireeva, I. V., & Maier, H. J. (1999). The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi: Part I- Aged microstructure and micro-mechanical modeling. Journal of Engineering Materials and Technology, Transactions of the ASME, 121(1), 19–27. https://doi.org/10.1115/1.2815993
Gall, K., H. Sehitoglu, Y. I. Chumlyakov, I. V. Kireeva, and H. J. Maier. “The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi: Part I- Aged microstructure and micro-mechanical modeling.” Journal of Engineering Materials and Technology, Transactions of the ASME 121, no. 1 (January 1, 1999): 19–27. https://doi.org/10.1115/1.2815993.
Gall K, Sehitoglu H, Chumlyakov YI, Kireeva IV, Maier HJ. The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi: Part I- Aged microstructure and micro-mechanical modeling. Journal of Engineering Materials and Technology, Transactions of the ASME. 1999 Jan 1;121(1):19–27.
Gall, K., et al. “The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi: Part I- Aged microstructure and micro-mechanical modeling.” Journal of Engineering Materials and Technology, Transactions of the ASME, vol. 121, no. 1, Jan. 1999, pp. 19–27. Scopus, doi:10.1115/1.2815993.
Gall K, Sehitoglu H, Chumlyakov YI, Kireeva IV, Maier HJ. The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi: Part I- Aged microstructure and micro-mechanical modeling. Journal of Engineering Materials and Technology, Transactions of the ASME. 1999 Jan 1;121(1):19–27.

Published In

Journal of Engineering Materials and Technology, Transactions of the ASME

DOI

EISSN

1528-8889

ISSN

0094-4289

Publication Date

January 1, 1999

Volume

121

Issue

1

Start / End Page

19 / 27

Related Subject Headings

  • Materials
  • 4017 Mechanical engineering
  • 4016 Materials engineering
  • 0913 Mechanical Engineering
  • 0912 Materials Engineering
  • 0910 Manufacturing Engineering