The Effect of Quenching Methods on Transformation Characteristics and Microstructure of an NiTiCu Shape Memory Alloy

Sampath, Santosh; Srinithi, R.; Santosh, S.; Sarangi, Panchami Padmasana; Fathima, J. Sherin

doi:10.1007/s12666-020-01909-9

Cited by 17 publications

(4 citation statements)

References 18 publications

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“…The temperature range for the phase transformation becomes longer when the location gets higher, which shows that the homogeneity of martensite is the highest at location H1, and it follows a descending trend when going up along the BD direction [42]. Adding Cu to replace a certain atomic number of Ni was reported to be able to reduce the thermal hysteresis, which is usually defined by the difference between A p and M p [46], or the difference between A f and M s [47]. In this work, the thermal hysteresis calculated by |A p −M p | of these three sections can be found for S12 (11 • C), S23 (12 • C), and S34 (16 • C).…”

Section: Dsc Phase Transformation Analysismentioning

confidence: 99%

Fabricating TiNiCu Ternary Shape Memory Alloy by Directed Energy Deposition via Elemental Metal Powders

et al. 2021

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In this paper, a TiNiCu shape memory alloy single-wall structure was fabricated by the directed energy deposition technique with a mixture of elemental Ti, Ni, and Cu powders following the atomic percentage of Ti50Ni45Cu5 to fully utilize the material flexibility of the additive manufacturing process to develop ternary shape memory alloys. The chemical composition, phase, and material properties at multiple locations along the build direction were studied, using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Vickers hardness testing, tensile testing, and differential scanning calorimetry. The location-dependent compositions of martensitic TiNi and austenitic TiNi phases, mechanical properties, and functional properties were investigated in detail. Variations were found in atomic compositions of Ti, Ni, and Cu elements along the build direction due to the complex interaction between elemental powders and laser processing. Good correlations were present among the chemical composition, phase constituent, hardness, and feature of phase transformation temperatures at various locations. The ultimate tensile strength of the as-deposited TiNiCu alloy is comparable with the previously reported additively manufactured TiNi binary alloys. By adding Cu, a much lower thermal hysteresis was achieved, which shows good feasibility of fabricating ternary TiNiCu shape memory alloys, using elemental powders in the directed energy deposition to adjust the thermal hysteresis.

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Section: Dsc Phase Transformation Analysismentioning

confidence: 99%

Fabricating TiNiCu Ternary Shape Memory Alloy by Directed Energy Deposition via Elemental Metal Powders

et al. 2021

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“…NiTi-based SMAs are widely known for their inimitable properties, including shape memory effect, superelasticity, and corrosion resistance [1,2]. Nitinol is used in many applications, such as endovascular devices, stents, dental clips, and vibration control of structures used in various civil engineering and aerospace applications [3][4][5][6]. Shape memory alloy remembers its initial shape after deformation and returns to that shape when heating and mechanical loading [7,8].…”

Section: Introductionmentioning

confidence: 99%

Surface quality and morphology of NiTiCuZr shape memory alloy machined using thermal-energy processes: an examination of comparative topography

Balasubramaniyan

Sampath²,

Rajkumar³

2022

Surf. Topogr.: Metrol. Prop.

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Adding alloying elements like copper (Cu) and zirconium (Zr) to binary NiTi shape memory alloys (NiTiCuZr SMA) raises the martensitic transition temperatures and functional fatigue properties while maintaining high corrosion and wear resistance. Therefore, it is essential to make high-precision SMA components with less damage to be machined into various complex shapes, sizes, and surface topographies to meet the needs of several engineering applications. In this research work, advanced machining processes like wire electrical discharge machining (WEDM) and fiber laser machining were employed to machine NiTiCuZr SMA and study their processing parameters' effects on the surface roughness, topography changes, and surface hardness. 3D surface topography and surface roughness on the machined surfaces were evaluated through contact and non-contact measurement techniques. The differential scanning calorimetry (DSC) test was conducted on the NiTiCuZr SMA before and after machining to confirm changes in the shape memory properties. When both processes were used at high energy levels, the formation of the resolidified layer and surface defects were more pronounced, increasing surface roughness. DSC curves for heating and cooling profiles show similar transformation temperatures for WEDM and laser machined NiTiCuZr SMA. On comparing two different machining processes, the WEDM process resulted in the Ra (µm) being 28.2% lower, the surface topography was smooth, and the microhardness was 11.9% lower than the samples machined using laser machining. This shows that machining of NiTiCuZr SMA using WEDM gives a better surface finish, reaching a fair decision that WEDM is a better alternative to laser machining.

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“…The secondary phase size and distribution depend on heat treatment and quenching. 15 The Ti 3 Ni 4 precipitate increased the formation of the trigonal phase (R-phase). 16,17 Subsequently, the phase transformation sequence changes, and minimizing Ti 3 Ni 4 precipitate from the alloys improved ductility and damping efficiency.…”

Section: Introductionmentioning

confidence: 99%

The effect of copper on phase transformation, microstructure and mechanical characterization of Ni_50-xTi₅₀Cu_x shape-memory alloy

Radhamani

Muralidharan

2022

Proceedings of the Institution of Mechanical Engineers, Part L:

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This research is related to the investigation of the influence of copper additions on phase transformation, microstructure and mechanical characterization of equiatomic NiTi shape-memory alloys. A typical vacuum arc melting furnace was used in the preparation of Ni50-xTi50Cux (x = 2, 5, 10, and 15 at.%) shape-memory alloys. The crystalline phase formation and phase transformation temperature were studied using X-ray diffraction and a differential scanning calorimeter. The morphology and chemical composition of the annealed samples were investigated using a field emission scanning electron microscope and energy-dispersive X-ray spectrometer analysis. The Vickers microhardness test was utilized in the analysis of the homogeneity of the alloy. The experimental results obtained from X-ray diffraction confirmed the coexistence of austenite and martensite phases along with the presence of a Ti2Ni and minor rutile phases. The crystalline sizes of the alloys were in the range of 42 to 78nm. An energy-dispersive spectrometer validated the distinct phases and precipitates in the alloys. The size and dispersion of the secondary phase in the alloy showed a significant influence on the increased hardness from 407HV to 470HV. The following NiTiCu alloy compositions were employed for low-temperature applications since their transition temperatures were below 100°C.

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The Effect of Quenching Methods on Transformation Characteristics and Microstructure of an NiTiCu Shape Memory Alloy

Cited by 17 publications

References 18 publications

Fabricating TiNiCu Ternary Shape Memory Alloy by Directed Energy Deposition via Elemental Metal Powders

Fabricating TiNiCu Ternary Shape Memory Alloy by Directed Energy Deposition via Elemental Metal Powders

Surface quality and morphology of NiTiCuZr shape memory alloy machined using thermal-energy processes: an examination of comparative topography

The effect of copper on phase transformation, microstructure and mechanical characterization of Ni_50-xTi₅₀Cu_x shape-memory alloy

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The Effect of Quenching Methods on Transformation Characteristics and Microstructure of an NiTiCu Shape Memory Alloy

Cited by 17 publications

References 18 publications

Fabricating TiNiCu Ternary Shape Memory Alloy by Directed Energy Deposition via Elemental Metal Powders

Fabricating TiNiCu Ternary Shape Memory Alloy by Directed Energy Deposition via Elemental Metal Powders

Surface quality and morphology of NiTiCuZr shape memory alloy machined using thermal-energy processes: an examination of comparative topography

The effect of copper on phase transformation, microstructure and mechanical characterization of Ni50-xTi50Cux shape-memory alloy

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The effect of copper on phase transformation, microstructure and mechanical characterization of Ni_50-xTi₅₀Cu_x shape-memory alloy