Behavior and effect of Ti2Ni phase during processing of NiTi shape memory alloy wire from cast ingot

Bhagyaraj, J.; Ramaiah, K.V.; Saikrishna, C.N.; Bhaumik, SK; Gouthama,

doi:10.1016/j.jallcom.2013.07.046

Cited by 66 publications

(26 citation statements)

References 19 publications

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“…From the aforementioned two martensite transformations, R-phase contributes to a very small transformation strain (about 1%), whilst B19′ phase causes a much larger transformation strain (around 10%) associated with a larger transformation barrier41. In addition, similar to refs 42 and 43, Ti 2 Ni particles promote the R phase transformation. The eutectic region was also investigated in details using TEM.…”

Section: Resultssupporting

confidence: 76%

Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires

Wang

Zhang

Chen

et al. 2016

Sci Rep

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NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19′ martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19′ martensitic transformation, and (V) plastic deformation of the specimen.

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Section: Resultssupporting

confidence: 76%

Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires

Wang

Zhang

Chen

et al. 2016

Sci Rep

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“…It should also be noted that multiple secondary phases, mainly Ti 2 Ni, were formed during the sintering process of NiTi alloys. Bhagyaraj et al [10] investigated the behavior and effect of Ti 2 Ni phase during processing of NiTi SMA and found that the amount of this secondary phase is about 1~2% by volume. Furthermore, Ti 2 Ni phase, as well as SiC particles, do not undergo phase transformation within the range of the testing temperatures.…”

Section: Resultsmentioning

confidence: 99%

Design, fabrication and characterization of porous Ti-rich Ti-Ni alloy based composites with near-zero thermal expansion behavior

Luo

Cao

et al. 2015

MATEC Web of Conferences

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Abstract. Porous Ti-rich Ti-Ni alloy based composites with near-zero thermal expansion (NZTE) behaviour tailored by micro-sized SiC particles were fabricated using powder metallurgy and a two-step designing strategy. At first, the Ni concentration was tuned to broaden the temperature range of negative thermal expansion (NTE) of porous Ti-Ni alloys; then micro-sized SiC particles of different amounts were introduced and co-sintered with mixed Ti and Ni powders having an optimized atomic ratio so as to obtain SiC/Ti-Ni composites with desirable thermal expansion performance. Results show that there is a clear correlation between the reverse martensitic transformation and NTE temperature range. The porous 12wt.%SiC/Ti-43.8at.%Ni composite exhibits very low coefficient of thermal expansion (CTE) of -0.976×10 -6 K -1 from 114.08 to 131.50 °C. It is proposed that the NTE behavior originates from the volume change accompanying the phase transition of the Ti-Ni matrix, and the NZTE performance of SiC/Ti-Ni composites is attributed to the combination of the NTE produced by the alloy matrix and the positive thermal expansion provided by the SiC phase.

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“…both the active SMA elements are off, the dynamics of the system is governed by (1), that represents the dynamic equilibrium equation of the slot along the dof direction.…”

Section: A Dynamical Schemementioning

confidence: 99%

“…The shape memory alloys (SMA) represent a class of metallic materials with particular thermo-mechanical and electrical properties, high power density and ability of producing comparatively large actuation strains/stresses [1]. Also polymers exhibits a sort of shape memory effect [2].…”

Section: Introductionmentioning

confidence: 99%

Shape memory actuator with slider and slot layout and single fan cooling

Borboni

Faglia

Palpacelli

2014

2014 IEEE/ASME 10th International Conference on Mechatronic and Embedded Systems and Applications (MESA)

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Behavior and effect of Ti2Ni phase during processing of NiTi shape memory alloy wire from cast ingot

Cited by 66 publications

References 19 publications

Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires

Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires

Design, fabrication and characterization of porous Ti-rich Ti-Ni alloy based composites with near-zero thermal expansion behavior

Shape memory actuator with slider and slot layout and single fan cooling

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