Effect of ageing temperatures on pseudoelasticity of Ni-rich NiTi shape memory alloy

Mohamad, Hishamiakim; Mahmud, Abdus Samad; Nashrudin, Muhammad Naqib; Razali, Muhammad Fauzinizam

doi:10.1063/1.5034539

Cited by 5 publications

(4 citation statements)

References 17 publications

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“…This is attributed to the formation of a metastable phase compound in the aging process, which alters the Ni concentration and, as a result, A f temperature [9]. Furthermore, the A f temperature dropped sharply with the annealing treatment at temperatures above 500 • C and remained constant for processing temperatures between 600 • C-700 • C. These changes of both A f and M f temperatures are consistent with previous studies [20][21][22][23][24]. These A f temperature behavior are similar in terms of function of annealing temperature to a previous work by Feng et al, which showed that the transformation temperatures increased when annealed at a lower temperature (i.e.…”

Section: Tuning a F Temperature Via Aging Treatmentsupporting

confidence: 90%

“…In terms of the A f temperature for these samples, it appears to be optimal for the samples aged at 400 • C for 5-10 min and annealed at 500 • C-550 • C for achieving elastocaloric materials for operation near room temperature. However, several studies revealed that superelastic properties, especially the recoverable and plateau stresses of Ni-Ti wires annealed at temperatures above around 500 • C-600 • C, decreased significantly, likely due to the plastic deformation of the austenite phase occurring before the stress-induced martensite transformation or due to the formation of large Ni 4 Ti 3 precipitates in the NiTi matrix [20,26,27]. It also should be noted that we might have achieved optimal A f temperature, but not necessarily optimal fatigue behavior depending on the size, morphology, and distribution of the precipitates.…”

Section: Tuning a F Temperature Via Aging Treatmentmentioning

confidence: 99%

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Tuning the temperature range of superelastic Ni-Ti alloys for elastocaloric cooling via thermal processing

et al. 2023

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Caloric cooling enlisting solid-state refrigerants is potentially a promising eco-friendly alternative to conventional cooling based on vapor compression. The most common refrigerant materials for elastocaloric cooling to date are Ni-Ti based superelastic shape memory alloys. Here, we have explored tuning the operation temperature range of Ni50.8Ti49.2 for elastocaloric cooling. In particular, we have studied the effect of thermal treatments (a.k.a. aging) on the transformation temperature, superelasticity, and elastocaloric effects of Ni50.8Ti49.2 shape memory alloy tubes. The isothermal compressive test revealed that the residual strain of thermally-treated Ni-Ti tubes at room temperature approaches zero as aging time is increased. Short-time aging treatment at 400 °C resulted in good superelasticity and elastocaloric cooling performance with a large tunable austenite finish (Af) temperature range of 24.7 °C, as determined from the Af temperature of the samples that were aged 5–120 minutes. The main reason of the property change is the formation of a different amount of Ni4Ti3 precipitates in the NiTi matrix. Our findings show that it is possible to tailor the Af temperature range for development of cascade elastocaloric cooling systems by thermally treating a starting single composition Ni-Ti alloy.

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Section: Tuning a F Temperature Via Aging Treatmentsupporting

confidence: 90%

Section: Tuning a F Temperature Via Aging Treatmentmentioning

confidence: 99%

Tuning the temperature range of superelastic Ni-Ti alloys for elastocaloric cooling via thermal processing

et al. 2023

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“…38 Mohamed et al observed that transformation temperatures decreased in NiTi alloys as a result of the hightemperature application of aging heat treatment. 39 The reduction in transformation temperatures may have adversely impacted the superelastic effect observed in the NiTi alloys. The decreases observed in the tensile and yield stress values in the aging heat-treated samples were thought to have been linked to the precipitates as well as to the transformation temperature.…”

Section: Evaluation Of Tensile and Hardness Testsmentioning

confidence: 99%

Experimental investigation of the effects of aging and cryogenic treatments on the mechanical properties of superelastic nickel-titanium shape-memory alloys

Güven¹,

Karataş

Gökkaya

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this study, electropolishing and two different heat treatments were applied to wires made of superelastic nickel-titanium (NiTi) shape-memory alloy (SMA) and their mechanical properties and stress-induced deformations were investigated. In experimental studies, cryogenic and aging heat treatments were applied to NiTi SMA wire samples and tensile test experiments were carried out to determine the effect of the heat treatments on their mechanical properties. Following the tensile test experiments conducted at room temperature (23 °C), the study investigated changes in the elemental composition, fracture modes, micro cracks, and phase structures and in the mechanical properties formed in the fracture region. Intermetallic phase structures (Ti2Ni, Ni3Ti, and Ni4Ti3) were observed in the X-ray diffraction (XRD) analyses. It was concluded that the aging heat treatment had directly affected the reduction in hardness. In particular, in samples without the aging heat treatment, a stress-induced decrease in the Ni and Ti ratios and an increase in the carbon (C) ratio were observed in the the chemical composition of the fracture surface of the superelastic NiTi SMA wires. It was determined that the changes in the chemical composition caused by stress had affected the mechanical properties negatively. In the fractography of the NiTi SMA wires, the samples exhibited mostly ductile fracture behavior with small dimples.

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“…However, control of the superelastic properties of Ni-rich NiTi alloys is difficult because the characteristics of the phase transformation sensitively vary with small changes in microstructure and composition [ 2 ]. The shape memory functions of Ni-rich NiTi alloys are known to be greatly affected by aging due to the formation of Ni 4 Ti 3 precipitates [ 6 , 7 , 8 ]. After aging, the martensite start temperature ( M s ) and austenite finish temperature ( A f ) tend to increase with increasing aging time due to Ni depletion of the matrix by precipitation of the Ni 4 Ti 3 phase [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Severe Plastic Deformation and Post-Deformation Heat Treatment on the Microstructure and Superelastic Properties of Ti-50.8 at.% Ni Alloy

Lee

Kim

2022

Materials

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Severe plastic deformation via high-ratio differential speed rolling (HRDSR) was applied to the Ni-rich Ti-50.8Ni alloy. Application of HRDSR and a short annealing time of 5 min at 873 K leads to the production of a partially recrystallized microstructure with a small grain size of 5.1 μm. During the aging process for the annealed HRDSR sample at 523 K for 16 h, a high density of Ni3Ti4 particles was uniformly precipitated over the matrix, resulting in the formation of an R phase as the major phase at room temperature. The aged HRDSR sample exhibits excellent superelasticity and superelastic cyclability. This achievement can be attributed to an increase in strength through effective grain refinement and particle strengthening by Ni3Ti4 and a decrease in the critical stress for stress-induced martensite (B19′) due to the presence of the R-phase instead of B2 as a major phase at room temperature. The currently proposed method for using HRDSR and post-deformation heat treatment allows for the production of Ni-rich NiTi alloys with excellent superelasticity in sheet form.

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Effect of ageing temperatures on pseudoelasticity of Ni-rich NiTi shape memory alloy

Cited by 5 publications

References 17 publications

Tuning the temperature range of superelastic Ni-Ti alloys for elastocaloric cooling via thermal processing

Tuning the temperature range of superelastic Ni-Ti alloys for elastocaloric cooling via thermal processing

Experimental investigation of the effects of aging and cryogenic treatments on the mechanical properties of superelastic nickel-titanium shape-memory alloys

Effect of Severe Plastic Deformation and Post-Deformation Heat Treatment on the Microstructure and Superelastic Properties of Ti-50.8 at.% Ni Alloy

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