Influence of Ni on martensitic phase transformations in NiTi shape memory alloys

Frenzel, Jan; George, E.P.; Dlouhý, A.; Somsen, Christoph; Wagner, Martin F.‐X.; Eggeler, Gunther

doi:10.1016/j.actamat.2010.02.019

Cited by 759 publications

(400 citation statements)

References 47 publications

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“…Figure 4a-b represents the as-spun states for M1 and M2 respectively. In the Figure 4a, it can be seen that the transformation temperatures (TTRs) decreased with increasing of the tangential velocity for M1 Ni-rich alloy, and this is in accordance with some references [11][12][13] , which has been attributed to the fact that if speed increases the cooling rate increased, leading to a decrease in grain size and therefore in TTRs. An opposite behavior was observed for Figure 4b.…”

Section: Effects Of Wheel Velocities and Heat Treatmentsupporting

confidence: 88%

Effect of Spun Velocities and Composition on the Microstructure and Transformation Temperatures of TiNi Shape Memory Ribbons

et al. 2016

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Ti-50.13Ni and Ti-49.62Ni (at.%) shape memory alloy ribbons were fabricated by melt-spinning method at different circumferential wheel velocities. The effects of wheel velocity, chemical composition and heat treatments on microstructure and Transformation temperature were investigated. Differences in wheel velocity led to differences in cooling rate and sample dimension, as well as in phase transformation temperatures. Two heat treatment conditions were studied, 350°C for 1h and 350°C for 5h. In the samples produced at high wheel velocity and heat-treated at 350°C for 5h, nanosized Ti-rich precipitates were observed in both chemical compositions. Cross-sectional microstructure was studied by optical microscopy; SEM was used to study the nanometric grains and nano precipitation. The transformation temperatures were analyzed by DSC.

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Section: Effects Of Wheel Velocities and Heat Treatmentsupporting

confidence: 88%

Effect of Spun Velocities and Composition on the Microstructure and Transformation Temperatures of TiNi Shape Memory Ribbons

et al. 2016

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“…The oxygen content was measured and it was found to be significantly higher in the FZ. For NiTi, the increase in oxygen content is known to decrease the transformation temperatures by favouring the formation of Ti-rich secondary phases [226], and this reinforces the need for a good shielding protection, so that the contamination in the FZ is not detrimental to the joints properties.…”

Section: Phase Transformation Temperaturesmentioning

confidence: 99%

Welding and Joining of NiTi Shape Memory Alloys: A Review

Oliveira

Miranda

Fernandes

2017

Progress in Materials Science

272

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“…pct Ti, which is consistent with Ti 2 Ni or Ti 4 Ni 2 O x particles, the later phase being more likely since it is more stable when forming an oxide. [42,52] Most of these particles are located at or near grain boundaries. After electropolishing for 2 minutes using 20 pct (by volume) H 2 SO 4 and 80 pct (by volume) CH 3 OH as an electrolyte, it can be seen that aligned martensitic twins are present in each grain and vary in direction depending on the specific grain orientation (as shown in Figure 2(b)).…”

Section: Resultsmentioning

confidence: 99%

“…Although most dynamic investigations have been focused on austenitic NiTi alloys, [29][30][31][32][33][34][35][36][37][38][39] martensitic NiTi alloys also exhibit thermoelastic behavior and even better damping capacity, [40,41] due to the movement of twin interfaces. NiTi SMAs, which are fully martensitic at room temperature, [42] often have coarse brittle Ti 2 Ni precipitates. These precipitates can severely reduce the mechanical properties, lead to significant internal stresses at precipitate-matrix interfaces, and aid in crack propagation during loading.…”

Section: Introductionmentioning

confidence: 99%

Influence of Dynamic Compression on Phase Transformation of Martensitic NiTi Shape Memory Alloys

Qiu

Young

Nie

2015

Metall Mater Trans A

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Shape memory alloys (SMAs) exhibit high damping capacity in both austenitic and martensitic phases, due to either a stress-induced martensite phase transformation or a stress-induced martensite variant reorientation, making them ideal candidates for vibration suppression devices to protect structural components from damage due to external forces. In this study, both quasi-static and dynamic compression was conducted on a martensitic NiTi SMA using a mechanical loading frame and on a Kolsky compression bar, respectively, to examine the relationship between microstructure and phase transformation characteristics of martensitic NiTi SMAs. Both endothermic and exothermic peaks disappear completely after experiencing deformation at a strain rate of 10 3 s À1 and to a strain of about 10 pct. The phase transformation peaks reappear after the deformed specimens were annealed at 873 K (600°C) for 30 minutes. As compared to samples from quasi-static loading, where a large amount of twinning is observed with a small amount of grain distortion and fracture, samples from dynamic loading show much less twinning with a larger amount of grain distortion and fracture.

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Influence of Ni on martensitic phase transformations in NiTi shape memory alloys

Cited by 759 publications

References 47 publications

Effect of Spun Velocities and Composition on the Microstructure and Transformation Temperatures of TiNi Shape Memory Ribbons

Effect of Spun Velocities and Composition on the Microstructure and Transformation Temperatures of TiNi Shape Memory Ribbons

Welding and Joining of NiTi Shape Memory Alloys: A Review

Influence of Dynamic Compression on Phase Transformation of Martensitic NiTi Shape Memory Alloys

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