Crystal structure and free energy of Ti 2 Ni 3 precipitates in Ti–Ni alloys from first principles

Lang, Peter; Wójcik, Tomasz; Povoden-Karadeniz, Erwin; Cirstea, Diana C.; Kozeschnik, Ernst

doi:10.1016/j.commatsci.2014.06.019

Cited by 13 publications

(3 citation statements)

References 23 publications

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“…Besides the matrix, we can observe two phases at C200: a ''black'' phase very rich in Ti and poor in Ni, and a ''grey'' phase rich in Cu and very poor in Ti. It is worth noticing that the ''black'' phase in both alloys is similar to Ti 2 Ni-like or (TiHfZr) 2 (NiCu) [26] and the grey phase is similar to Ti 3 Ni 4 -like or (TiHfZr) 3 (NiCu) 4 [42][43][44], which is consistent with both XRD diffractograms indexing shown in Fig. 6a, b 9b, the maximum reversible strain (e r ) is up to 2% whereas no irreversible strain (eirr) is observed.…”

Section: Transformation Characterizationmentioning

confidence: 99%

Investigation and Composition Characterization of a “NiTi-like” Alloy Combining High Temperature Shape Memory and High Entropy

Peltier

Lohmuller

Meraghni

et al. 2020

Shap. Mem. Superelasticity

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New high temperature shape memory alloys with five or more elements are under development and present attractive performances for several functional applications. These active metallic materials are called high entropy and high temperature shape memory alloys (HE-HT-SMAs). This work deals with the characterization of an alloy that combines high temperature shape memory effect and high entropy effect features, a NiCuTiHfZr alloy. The evolution of the phase transformation and the shape memory effect during thermal fatigue was compared with a ternary alloy NiTiZr. Ingots were prepared in a cold crucible and alloys were characterized after thermal cycling at 600 K without a protective gas atmosphere. Optical microscope, X-ray diffraction, and scanning electron microscopy observations showed the presence of martensite in this unpublished alloy at room temperature. The differential scanning calorimetry (DSC) tests showed that martensitic transformation takes place at high temperature. High temperature thermal cycling was performed during a three-point bending tests under constant load without a protective atmosphere. Thermomechanical results showed that high entropy effects increase the operating behavior at high temperature. Hence this new composition of NiCuTiHfZr alloy can be used as an actuator for aerospace and aeronautic application.

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Section: Transformation Characterizationmentioning

confidence: 99%

Investigation and Composition Characterization of a “NiTi-like” Alloy Combining High Temperature Shape Memory and High Entropy

Peltier

Lohmuller

Meraghni

et al. 2020

Shap. Mem. Superelasticity

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show abstract

“…The macrostructure or microstructure of AM products, depending on the mel and solidification of the melt pool, is investigated after metallographic prepara As mentioned above, any deviation of the binary NiTi alloy composition from 50:50 stoichiometry develops the transformation temperature shifts, and this can be further evoked through precipitation of several types of precipitates formed in alloy microstructure after primary processing, for example, NiTi 2 or TiO 2 and TiC in the case of contamination [5,15,[82][83][84]. Furthermore, thermal treatment of the NiTi alloy subsequent to casting or additive manufacturing induces diffusion processes and additional precipitation of various phase particles: metastable Ni 4 Ti 3 , metastable Ni 3 Ti 2 , or stable Ni 3 Ti [85][86][87][88][89][90][91][92][93][94]. The heat treatment, also called post-processing treatment [15], can consist of annealing (for residual stress release, homogenization, or solution treatment) or additional aging (precipitation strengthening) [82,[90][91][92]95].…”

Section: Evaluating Properties Of Am Niti Alloymentioning

confidence: 99%

A Review on Additive Manufacturing Methods for NiTi Shape Memory Alloy Production

Kubášová,

Drátovská,

Losertová

et al. 2024

Materials

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The NiTi alloy, known as Nitinol, represents one of the most investigated smart alloys, exhibiting a shape memory effect and superelasticity. These, among many other remarkable attributes, enable its utilization in various applications, encompassing the automotive industry, aviation, space exploration, and, notably, medicine. Conventionally, Nitinol is predominantly produced in the form of wire or thin sheets that allow producing many required components. However, the manufacturing of complex shapes poses challenges due to the tenacity of the NiTi alloy, and different processing routes at elevated temperatures have to be applied. Overcoming this obstacle may be facilitated by additive manufacturing methods. This article provides an overview of the employment of additive manufacturing methods, allowing the preparation of the required shapes of Nitinol products while retaining their exceptional properties and potential applications.

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“…A diffusion couple study is a practical approach to investigate diffusion phenomena in solid-state conditions. The formation of different intermetallic compounds in the Ti–Ni binary system is based on diffusional transformation, including the metastable phases of Ti 3 Ni 4 → Ti 2 Ni 3 → TiNi 3 (stable), where temperature and holding duration are critical factors that determine the kinetics of this process [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

Understanding Interfacial Reactions in Ti–Ni Diffusion Couple

et al. 2023

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The diffusion phenomenon in the Ti–Ni binary system was investigated at a temperature of 1173 K. Microstructure and texture analysis revealed the formation of three stable intermetallic compounds, namely Ti2Ni, TiNi, and TiNi3, as well as two metastable intermetallic compounds, including Ti3Ni4 and Ti2Ni3, at the interfacial diffusion zone. The nucleation surface energy increase was analytically estimated, and marker experiments were conducted using thoria particles, both of which showed that Ti2Ni was the first compound to form at the Ti–Ni diffusion interface. At a temperature of 1173 K, using the Wagner method, the integrated diffusion coefficients for the Ti2Ni, TiNi, and TiNi3 phases were calculated to be 3.53 × 10−12, 18.1 × 10−15, and 6.2 × 10−15 m2/s, for, respectively.

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Crystal structure and free energy of Ti 2 Ni 3 precipitates in Ti–Ni alloys from first principles

Cited by 13 publications

References 23 publications

Investigation and Composition Characterization of a “NiTi-like” Alloy Combining High Temperature Shape Memory and High Entropy

Investigation and Composition Characterization of a “NiTi-like” Alloy Combining High Temperature Shape Memory and High Entropy

A Review on Additive Manufacturing Methods for NiTi Shape Memory Alloy Production

Understanding Interfacial Reactions in Ti–Ni Diffusion Couple

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