Effect of Heat Treatment on the Martensitic Transformation in TiNi Compound

Honma, Tetsuo; Takei, H.

doi:10.2320/jinstmet1952.39.2_175

Cited by 52 publications

(18 citation statements)

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“…In contrast, the ER curves of 51.23, 51.54, and 51.75 specimens show no apparent change due to MT, whereas Table 1 Analytical compositions, characteristic temperatures, latent heat, and entropy change of the prepared alloys Ni content (at.%) a T p and Q M-P are determined using high-resolution DSC that of the 51.23 sample has a faint hysteresis at around 180 K. Although the origin of this small hysteresis is not clear, no MT could be detected by other techniques. These results suggest that these three specimens kept the P phase condition down to 4 K. It is seen that the ER curves started to increase at around 300 K with decreasing temperature, becoming almost constant in the temperature region below *100 K. Such a negative temperature dependence of the ER curve has been reported in some previous papers on not only Ni-rich Ti-Ni alloys, but also Ti-Ni-Fe (more than 6 at.% Fe) alloys [6,8,9], which is discussed in relation to the concept of strain glass by Ren et al [3]. All the determined characteristic temperatures, T 0 , T Ms , and T Af , are listed in Table 1 and plotted in Fig.…”

Section: Determination Of Transformation Temperaturessupporting

confidence: 78%

Composition Dependences of Entropy Change and Transformation Temperatures in Ni-rich Ti–Ni System

Niitsu

Kimura

et al. 2015

Shap. Mem. Superelasticity

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For Ni-rich Ti-Ni alloys, physical properties such as specific heat and electric resistance were systematically investigated. The B2/B19 0 martensitic transformation temperatures ranging from 180 to 373 K were determined for Ni contents of 49.98-51.09 %, and a sudden disappearance of martensitic transformation was confirmed for Ni contents greater than 51.23 %, which has also been well reported in the literatures. The entropy change was also evaluated from differential scanning calorimeter measurement, and it was clarified that the entropy change plotted to T 0 temperature shows an S-shaped curve, starting to drastically decrease at about 300 K. Thermodynamic approaches were then carried out attempting to determine the reason for the disappearance of transformation. The entropy change estimated from direct measurements of specific heats for 51.75 Ni (B2) and 50.92 Ni (B19 0 ) was found to be more consistent with the experimental data, rather than the calculated curve based on the Debye model for vibration specific heat. It was proposed that the equilibrium between the parent and martensite phases obeys the Clausius-Clapeyron relationship in the composition-temperature system. Using the constructed composition-temperature diagram, the disappearance of martensitic transformation in the Ti-Ni system can be well understood as being due to the drastic increase of hysteresis at low temperature.

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Section: Determination Of Transformation Temperaturessupporting

confidence: 78%

Composition Dependences of Entropy Change and Transformation Temperatures in Ni-rich Ti–Ni System

Niitsu

Kimura

et al. 2015

Shap. Mem. Superelasticity

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“…high temperature CsCl (B2) phase(1), low temperature monoclinic (M) phase (4) and intermediate rhombohedral (R) phase (1). Therefore, three types of transformaeach phase depends on the composition of the alloys and aging treatments(5)(11) (12), and furthermore on the heat treatment after hot-or cold-working (13) and thermal cycling (2)(14) (15 …”

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confidence: 99%

Effect of Heat Treatment after Cold Working on the Phase Transformation in TiNi Alloy

1987

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The effect of heat treatment in the range 633 K-933 K on the phase transformations among three types of phases, i.e. the CsCl (B2)-, rhombohedral (R)-and monoclinic (M)-phases in Ti-49.7, 50.2 and 50.6 at%Ni alloys have been investigated using the differential scanning calorimetry (DSC) method. It has been confirmed that the phase transformations that occur during heating and cooling can be perature range in which R-phase is stable becomes wider with increasing Ni content. The transformation temperature of R-phase was found to decrease with increasing heat treatment temperature. The starting point of the R-phase transformation in these alloys heat-treated at 633 K was estimated approximately at 330 K, which was almost independent of Ni content.

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“…This factor depends of the fabrication process, thermomechanical treatments and others. Normally alloys with high dislocation densities present two peaks that correspond to R and martensitic phases 8,12 . Wires utilized in this work were obtained by cold-drawn process, resulting in a material with high dislocation density.…”

Section: Study Calorimetrical Of Heat Treatments Influences In Phase mentioning

confidence: 99%

“…These precipitates make martensitic transformation more easier (increase of M s in Figure 3) because they act as preferential sites for nucleation of reaction, inhibiting and/or suppressing the appearance of the R-phase. Precipitations occur from diffusional processes which involve changes in chemical composition, modifying transformation temperatures of such a way that increase critical temperatures, in case of the Ni-rich alloys 5,[11][12][13] . A second important factor is about deformation stage or dislocation density configurations.…”

Section: Study Calorimetrical Of Heat Treatments Influences In Phase mentioning

confidence: 99%

Heat treatments and thermomechanical cycling influences on the R-phase in Ti-Ni shape memory alloys

et al. 2010

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This article studies changes observed on the R-phase thermoelastic behavior in a near-equiatomic Ti-Ni shape memory alloy. Three kinds of procedures have been performed: different treatments, thermomechanical cycling under constant loading in shape memory helical springs and thermal cycling in as-treated and trained samples. Several heat treatments were carried out to investigate evolution of the R-phase by differential scanning calorimetry (DSC). A heat treatment was chosen on which R-phase is absent. Shape memory springs were produced and submitted to a training process in an apparatus by tensioning the springs under constant loading. Thermal cycling in DSC was realized in as-treated and trained samples. Several aspects of one-step (B2→B19') and two-steps (B2→R→B19') martensitic transformations and R-phase formation and their evolution during tests were observed and discussed.

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Effect of Heat Treatment on the Martensitic Transformation in TiNi Compound

Cited by 52 publications

References 0 publications

Composition Dependences of Entropy Change and Transformation Temperatures in Ni-rich Ti–Ni System

Composition Dependences of Entropy Change and Transformation Temperatures in Ni-rich Ti–Ni System

Effect of Heat Treatment after Cold Working on the Phase Transformation in TiNi Alloy

Heat treatments and thermomechanical cycling influences on the R-phase in Ti-Ni shape memory alloys

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