Details
| Original language | English |
|---|---|
| Pages (from-to) | 7422-7431 |
| Number of pages | 10 |
| Journal | Acta materialia |
| Volume | 61 |
| Issue number | 19 |
| Publication status | Published - 24 Sept 2013 |
Abstract
Shape memory properties of a Ni50.3Ti29.7Hf 20 (at.%) polycrystalline alloy were characterized after selected heat treatments. The effects of heat treatment temperature and time on the transformation temperatures (TTs) and temperature hysteresis were determined by differential scanning calorimetry. Thermal cycling under constant compressive stress was carried out to reveal the changes in transformation strain, temperature hysteresis, and TT as a function of stress. Isothermal stress cycling experiments were conducted to reveal the critical stresses, transformation strain, and stress hysteresis as a function of temperature. The crystal structure and lattice parameters of the transforming phases were determined by X-ray diffraction at selected temperatures. Precipitate characteristics and martensite morphology were revealed by transmission electron microscopy. Precipitation was found to alter the martensite morphology and significantly improve the shape memory properties of the Ni-rich NiTiHf alloy. For the peak aged condition shape memory strains of up to 3.6%, the lowest hysteresis, and a fully reversible superelastic response were observed at temperatures up to 240 C. In general, the nickel-rich NiTiHf polycrystalline alloy exhibited a higher work output (≈16.5 J cm-3) than other NiTi-based high temperature alloys.
Keywords
- High temperature, Mechanical tests, NiTiHf, Phase transformations, Shape memory alloys
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Ceramics and Composites
- Materials Science(all)
- Polymers and Plastics
- Materials Science(all)
- Metals and Alloys
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In: Acta materialia, Vol. 61, No. 19, 24.09.2013, p. 7422-7431.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Effects of nanoprecipitation on the shape memory and material properties of an Ni-rich NiTiHf high temperature shape memory alloy
AU - Karaca, H. E.
AU - Saghaian, S. M.
AU - Ded, G.
AU - Tobe, H.
AU - Basaran, B.
AU - Maier, H. J.
AU - Noebe, R. D.
AU - Chumlyakov, Y. I.
N1 - Funding information: This work was supported in part by the NASA Fundamental Aeronautics Program, Aeronautical Sciences Project and the NASA EPSCOR program under Grant NNX11AQ31A and the RFBR project with Grant 12-08-91331 NNIO-a.
PY - 2013/9/24
Y1 - 2013/9/24
N2 - Shape memory properties of a Ni50.3Ti29.7Hf 20 (at.%) polycrystalline alloy were characterized after selected heat treatments. The effects of heat treatment temperature and time on the transformation temperatures (TTs) and temperature hysteresis were determined by differential scanning calorimetry. Thermal cycling under constant compressive stress was carried out to reveal the changes in transformation strain, temperature hysteresis, and TT as a function of stress. Isothermal stress cycling experiments were conducted to reveal the critical stresses, transformation strain, and stress hysteresis as a function of temperature. The crystal structure and lattice parameters of the transforming phases were determined by X-ray diffraction at selected temperatures. Precipitate characteristics and martensite morphology were revealed by transmission electron microscopy. Precipitation was found to alter the martensite morphology and significantly improve the shape memory properties of the Ni-rich NiTiHf alloy. For the peak aged condition shape memory strains of up to 3.6%, the lowest hysteresis, and a fully reversible superelastic response were observed at temperatures up to 240 C. In general, the nickel-rich NiTiHf polycrystalline alloy exhibited a higher work output (≈16.5 J cm-3) than other NiTi-based high temperature alloys.
AB - Shape memory properties of a Ni50.3Ti29.7Hf 20 (at.%) polycrystalline alloy were characterized after selected heat treatments. The effects of heat treatment temperature and time on the transformation temperatures (TTs) and temperature hysteresis were determined by differential scanning calorimetry. Thermal cycling under constant compressive stress was carried out to reveal the changes in transformation strain, temperature hysteresis, and TT as a function of stress. Isothermal stress cycling experiments were conducted to reveal the critical stresses, transformation strain, and stress hysteresis as a function of temperature. The crystal structure and lattice parameters of the transforming phases were determined by X-ray diffraction at selected temperatures. Precipitate characteristics and martensite morphology were revealed by transmission electron microscopy. Precipitation was found to alter the martensite morphology and significantly improve the shape memory properties of the Ni-rich NiTiHf alloy. For the peak aged condition shape memory strains of up to 3.6%, the lowest hysteresis, and a fully reversible superelastic response were observed at temperatures up to 240 C. In general, the nickel-rich NiTiHf polycrystalline alloy exhibited a higher work output (≈16.5 J cm-3) than other NiTi-based high temperature alloys.
KW - High temperature
KW - Mechanical tests
KW - NiTiHf
KW - Phase transformations
KW - Shape memory alloys
UR - http://www.scopus.com/inward/record.url?scp=84885669684&partnerID=8YFLogxK
U2 - 10.1016/j.actamat.2013.08.048
DO - 10.1016/j.actamat.2013.08.048
M3 - Article
AN - SCOPUS:84885669684
VL - 61
SP - 7422
EP - 7431
JO - Acta materialia
JF - Acta materialia
SN - 1359-6454
IS - 19
ER -