Effect of heat treatment atmosphere on the multistage martensitic transformation in aged Ni-rich Ti–Ni alloys

Fujishima, Kousuke; Nishida, Minoru; Morizono, Yasuhiro; Yamaguchi, Kazuya; Ishiuchi, Kentarou; Yamamuro, Takateru

doi:10.1016/j.msea.2006.05.048

Cited by 20 publications

(12 citation statements)

References 7 publications

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“…Details such as heat treatment atmosphere are described elsewhere. 6,11,15,16) Some specimens were aged at 773 K for 3.6 ks and then quenched into ice water. The solution-treated and aged specimens were subjected to thermal cycling in the temperature range between 77 and 373 K by alternately dipping them into liquid nitrogen and boiling water for 1 min at a time.…”

Section: Methodsmentioning

confidence: 99%

“…These differences between M1*, M2* and M3* are attributable to the heterogeneous microstructure with variations in size and distribution density of Ti 3 Ni 4 precipitates in the aged specimen, as mentioned above. 39,11,1416) After 100 thermal cycles, ¦A1*, ¦(A2* + AR*) and ¦A3* are 3, 3 and 11 K, respectively. These results suggest that the influence of thermal cycling is also more pronounced in forward transformation than in reverse transformation in the aged specimen with heterogeneous microstructure.…”

Section: Methodsmentioning

confidence: 99%

“…39,11,1416) These facts indicate that a different thermal cycling effect can be expected in each transformation event (i.e., in M1, M2 and M3 transformations). In other words, the effect of precipitation morphology on transformation behavior can be observed systematically in an identical specimen.…”

Section: )mentioning

confidence: 97%

“…39,11,1416) The transformation sequence during MMT is also disputed. 7,9,14) The present authors have previously reported the transformation sequence during the quadruple-stage transformation in Ti50.8 at% Ni, as determined by in-situ SEM.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Thermal Cycling on Multistage Martensitic Transformation in Aged Ti–50.8 at% Ni Alloy

et al. 2013

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The effect of thermal cycling on multistage martensitic transformation (MMT) in aged Ti50.8 at% Ni alloy was investigated. The specimens were solution-treated at 1273 K for 3.6 ks and then aged at 773 K for 3.6 ks in vacuum without atmosphere regulation. Upon cooling, the aged specimens clearly showed quadruple-stage transformation denoted as B2 ¼ R ¼ M1 ¼ M2 ¼ M3. The peak temperatures of exothermic reactions R*, M1*, and M2* (corresponding to the R-phase, M1 and M2 transformations, respectively) in the differential scanning calorimetry (DSC) cooling curve were rather stable up to 100 thermal cycles, since there were fine Ti 3 Ni 4 precipitates with high distribution density in the intermediate and grain boundary regions. These precipitates prevented the formation of dislocations during thermal cycling. On the other hand, the peak temperature of exothermic reaction M3* (corresponding to the M3 transformation) drastically decreased with increasing the number of thermal cycles since there were large Ti 3 Ni 4 precipitates with low distribution density. Many dislocations were observed in the central regions of grains after 100 thermal cycles.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: )mentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Effect of Thermal Cycling on Multistage Martensitic Transformation in Aged Ti–50.8 at% Ni Alloy

et al. 2013

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“…The path of the martensitic phase transition was * david.holec@unileoben.ac.at shown to change once oxygen was a part of a residual gas during the heat treatment. In order to explain the observed effects, Fujishima et al [14] and recently also Ravari et al [15] suggested a link between the precipitation of the Ni 4 Ti 3 phase and the composition of the heat treatment atmosphere. While the scenario proposed by Nishida et al [13] focused on the role of the residual oxygen, some other gaseous components, that may have contributed to the overall pressure of residual gasses and thus to the varying PTTs, were not taken into account.…”

Section: Introductionmentioning

confidence: 99%

Ab initiostudy of point defects in NiTi-based alloys

et al. 2014

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Changes in temperature or stress state may induce reversible B2↔(R)↔ B19' martensitic transformations and associated shape memory effects in close-to-stoichiometric nickel-titanium (NiTi) alloys. Recent experimental studies confirmed a considerable impact of the hydrogen-rich aging atmosphere on the subsequent B2 austenite ↔ B19' martensite transformation path. In this paper, we employ Density Functional Theory to study properties of Ar, He, and H interstitials in B2 austenite and B19' martensite phases. We show that H interstitials exhibit negative formation energies, while Ar and He interstitials yield positive values. Our theoretical analysis of slightly Ni-rich Ni-Ti alloys with the austenite B2 structure shows that a slight over-stoichiometry towards Ni-rich compositions in a range 51-52 at.% is energetically favorable. The same conclusion holds for H-doped NiTi with the H content up to ≈ 6 at.%. In agreement with experimental data we predict H atoms to have a strong impact on the martensitic phase transformation in NiTi by altering the mutual thermodynamic stability of the high-temperature cubic B2 and the low-temperature monoclinic B19' phase of NiTi. Hydrogen atoms are predicted to form stable interstitial defects. As this is not the case for He and Ar, mixtures of hydrogen and the two inert gases can be used in annealing experiments to control H partial pressure when studying the martensitic transformations in NiTi in various atmospheres.

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Metals and Alloys

Schryvers

2012

Handbook of Nanoscopy

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Effect of heat treatment atmosphere on the multistage martensitic transformation in aged Ni-rich Ti–Ni alloys

Cited by 20 publications

References 7 publications

Effect of Thermal Cycling on Multistage Martensitic Transformation in Aged Ti–50.8 at% Ni Alloy

Effect of Thermal Cycling on Multistage Martensitic Transformation in Aged Ti–50.8 at% Ni Alloy

Ab initiostudy of point defects in NiTi-based alloys

Metals and Alloys

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Effect of heat treatment atmosphere on the multistage martensitic transformation in aged Ni-rich Ti–Ni alloys

Cited by 20 publications

References 7 publications

Effect of Thermal Cycling on Multistage Martensitic Transformation in Aged Ti&ndash;50.8 at% Ni Alloy

Effect of Thermal Cycling on Multistage Martensitic Transformation in Aged Ti&ndash;50.8 at% Ni Alloy

Ab initiostudy of point defects in NiTi-based alloys

Metals and Alloys

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Product

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Effect of Thermal Cycling on Multistage Martensitic Transformation in Aged Ti–50.8 at% Ni Alloy

Effect of Thermal Cycling on Multistage Martensitic Transformation in Aged Ti–50.8 at% Ni Alloy