Comparative study of R-phase martensitic transformations in TiNi-based shape memory alloys induced by point defects and precipitates

Chang, P. C.; Ko, Musong; Ramachandran, B.; Kuo, Y. K.; Chien, Chiang‐Ju; Wu, Shyi‐Kaan

doi:10.1016/j.intermet.2017.01.008

Cited by 12 publications

(26 citation statements)

References 35 publications

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“…However, excess Ni content has a strong influence on the martensitic transformation features of Ti 50- x Ni 50+ x SMA, as the martensitic transition remains intact for x < 1.3 and the martensitic transition is suppressed for x ≥1.3 23 , 26 . In our earlier works 27 , 28 , we showed that low- T aging/annealing also results in a significant change in the martensitic transformation features of Ti 48.7 Ni 51.3 SMA. That is, the strain glass order in as-quenched Ti 48.7 Ni 51.3 is transformed to the R-martensite order by the aging process 27 .…”

Section: Introductionmentioning

confidence: 65%

“…In our earlier works 27 , 28 , we showed that low- T aging/annealing also results in a significant change in the martensitic transformation features of Ti 48.7 Ni 51.3 SMA. That is, the strain glass order in as-quenched Ti 48.7 Ni 51.3 is transformed to the R-martensite order by the aging process 27 . This is mainly due to the local lattice deformations which induced by the aging created Ti 3 Ni 4 precipitates.…”

Section: Introductionmentioning

confidence: 65%

“…From these studies, it was shown that both the Fermi energy ( E F ) and the density of states (DOS) of TiNi SMAs vary considerably with the Fe concentration ( x ). In addition, the phonon-electron coupling is noticeably weakened by Fe substitution, which leads to the change in the transformation features of these SMAs 27 , 31 .…”

Section: Introductionmentioning

confidence: 99%

“…In particular, the highly sensitive Seebeck coefficient and thermal conductivity measurements on the Ti 50 Ni 50- x Fe x SMAs will be crucial to explore their thermal transport properties, which have not yet been fully explored. In this respect, we recently reported the electrical and thermal transport properties of the Ti 50 Ni 48.5 Fe 1.5 and Ti 50 Ni 46 Fe 4 SMAs 27 , 31 . From these studies, it was shown that both the Fermi energy ( E F ) and the density of states (DOS) of TiNi SMAs vary considerably with the Fe concentration ( x ).…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of martensitic and strain-glass transitions of the Fe-substituted TiNi shape memory alloys probed by transport and thermal measurements

Balakrishnan

Chang

Kuo

et al. 2017

Sci Rep

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The electrical resistivity, Seebeck coefficient, thermal conductivity, and specific heat of Ti50Ni50-xFex (x = 2.0–10.0 at.%) shape memory alloys (SMAs) were measured to investigate the influence of point defects (Fe) on the martensitic transformation characteristics. Our results show that the Ti50Ni48Fe2 and Ti50Ni47Fe3 SMAs have a two-step martensitic transformation (B2 → R and R → B19′), while the Ti50Ni46Fe4, Ti50Ni44.5Fe5.5, and Ti50Ni44Fe6 SMAs display a one-step martensitic transition (B2 → R). However, the compounds Ti50Ni42Fe8 and Ti50Ni40Fe10 show strain glass features (frozen strain-ordered state). Importantly, the induced point defects significantly alter the martensitic transformation characteristics, namely transition temperature and width of thermal hysteresis during the transition. This can be explained by the stabilization of austenite B2 phase upon Fe substitution, which ultimately leads to the decrease in enthalpy that associated to the martensitic transition. To determine the boundary composition that separates the R-phase and strain glass systems in this series of SMAs, a Ni-rich specimen Ti49Ni45Fe6 was fabricated. Remarkably, a slight change in Ti/Ni ratio converts Ti49Ni45Fe6 SMA into a strain glass system. Overall, the evolution of phase transformation in the Fe-substituted TiNi SMAs is presumably caused by the changes in local lattice structure via the induced local strain fields by Fe point defects.

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Section: Introductionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characteristics of martensitic and strain-glass transitions of the Fe-substituted TiNi shape memory alloys probed by transport and thermal measurements

Balakrishnan

Chang

Kuo

et al. 2017

Sci Rep

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“…This causes the precipitation of the Ni 4 Ti 3 compound which contributes to the stabilization of the NiTi phase with trigonal lattice (R phase) [19]. Precipitation of the Ni 4 Ti 3 phase, coherent with the NiTi matrix, is responsible for the higher hardness of the Mg composite reinforced with Nirich Ni-Ti particulates when compared to the hardness of Mg composites reinforced with equiatomic Ni-Ti particulates or Ti -rich Ni-Ti particulates [20].…”

Section: Magnesium Composites Reinforced With Mechanical Alloyed Nickmentioning

confidence: 99%

Microstructural Aspects of Some Magnesium Matrix Composites Reinforced with Amorphous/Nanocrystalline Ni-Ti Particulates

Dumitrescu¹,

Gherghescu²,

Ciucă³

et al. 2019

Rev. Chim.

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Two magnesium matrix composites reinforced with 3 and 10% Ni-Ti particulates, respectively, were obtained by plasma sintering. The reinforcement material was obtained by grinding a mixture of powders of 68% Ni and 32% Ti atomic percent in a high energy mill for 40 hours. Particulates resulting from mechanical alloying have a partially amorphous and partially nanocrystalline structure, consisting of the following phases: Ni solid solution, Ti2Ni and NiTi (B2) phase. After sintering, both the matrix and the reinforcement material are nanocrystalline and the particulates have a polyphase structure, consisting of Ni(Ti), NiTi (R phase) and Ni4Ti3. The hardness of these composites is superior to the hardness of magnesium matrix composites reinforced with Ni-Ti particulates having 50% Ni / 50% Ti and 32% Ni / 68% Ti chemical compositions obtained under the same conditions and corresponding proportions of reinforcement material.

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A Perspective on Elastocaloric Effect in Ti–Ni-Based Shape Memory Alloys

Aaltio

Fukuda

Kakeshita

2019

Shap. Mem. Superelasticity

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Comparative study of R-phase martensitic transformations in TiNi-based shape memory alloys induced by point defects and precipitates

Cited by 12 publications

References 35 publications

Characteristics of martensitic and strain-glass transitions of the Fe-substituted TiNi shape memory alloys probed by transport and thermal measurements

Characteristics of martensitic and strain-glass transitions of the Fe-substituted TiNi shape memory alloys probed by transport and thermal measurements

Microstructural Aspects of Some Magnesium Matrix Composites Reinforced with Amorphous/Nanocrystalline Ni-Ti Particulates

A Perspective on Elastocaloric Effect in Ti–Ni-Based Shape Memory Alloys

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