Microstructural Evolution During the Hot Deformation of Ti-55Ni (at. pct) Intermetallic Alloy

Khamei, Aliakbar; Dehghani, K.

doi:10.1007/s11661-010-0338-8

Cited by 27 publications

(13 citation statements)

References 17 publications

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“…7a and b that the microstructures exhibit localized plastic flow and/or adiabatic shear. A similar instability phenomenon was observed in as-cast Nitinol 60 alloy at a strain rate of 0.35 s -1 and temperatures of 900°C and 950°C [21]. Flow localization is a common deformation mode observed in plastic working.…”

supporting

confidence: 71%

“…It is generally expected that the optimal deformation condition is met when the efficiency is the maximum. However, some materials may exhibit unstable flow characteristics during the deformation process, such as flow localization, adiabatic shear, void generation, and cracks [9,21]. Prasad [5,6] has derived the following instability criterion to identify whether or not the instabilities occur in the hot deformation process:…”

Section: Processing Mapmentioning

confidence: 99%

“…8b. Dehghani and Khamei [19,21] have investigated the hot deformation behavior of as-casted Nitinol 60 alloy and proposed that DRX occurs by bulging the grain boundaries caused by strain inducedgrain-boundary migration (SIBM). Such a nucleation mechanism is found in reference [23].…”

mentioning

confidence: 99%

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Optimization of hot working parameters of as-forged Nitinol 60 shape memory alloy using processing maps

Shu

Wang

et al. 2015

Met. Mater. Int.

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The hot deformation behavior of as-forged Nitinol 60 alloy (60 wt% Ni, 40 wt% Ti) was studied over the ranges of temperature, 650-850°C, and strain rate, 0.01-1 s -1 , using isothermal constant strain rate compression tests in a Gleeble-3500 simulator. The processing maps, based on the dynamic materials model, were developed to optimize the hot working parameters. The results show that the deformation parameters have a marked effect on the power dissipation efficiency and the instability parameter. A single unstable region (650-775°C, 0.037-1 s -1 ), associated with flow localization and/or adiabatic shear, is detected from the processing map. This should be avoided in hot working process. The optimized hot working conditions correspond to 680-790°C, 0.01-0.025 s -1 with peak efficiency of 0.45 at 720°C, 0.01 s -1 , and 820-850°C, 0.1-1 s -1 with peak efficiency of 0.5 at 850°C, 1 s -1 . Microstructure observations indicate that the main deformation mechanism of optimized domains involves dynamic recrystallization.

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supporting

confidence: 71%

Section: Processing Mapmentioning

confidence: 99%

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Optimization of hot working parameters of as-forged Nitinol 60 shape memory alloy using processing maps

Shu

Wang

et al. 2015

Met. Mater. Int.

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“…9,10 However, formability is one of the most import characteristics of materials to attain the required near-net shape and high quality for finished products. 11 The flow stress during hot working can be a function of the deformation parameters: i.e., strain, strain rate, and temperature. In this regard, various constitutive equations were developed based on the experimental data to describe the sensitivity of the flow stress to the strain, strain rate, and temperature.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Hot Ductility of AA6061 Aluminum Alloy After Severe Plastic Deformation

Khamei

Dehghani

Mahmudi

2015

JOM

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Solutionized AA6061 aluminum alloy was processed by equal-channel angular pressing followed by cold rolling. The hot ductility of the material was studied after severe plastic deformation. The hot tensile tests were carried out in the temperature range of 300-500°C and at the strain rates of 0.0005-0.01 s À1 . Depending on the temperature and strain rate, the applied strain level exhibited significant effects on the hot ductility, strain-rate sensitivity, and activation energy. It can be suggested that the possible mechanism dominated the hot deformation during tensile testing is dynamic recovery and dislocation creep. Constitutive equations were developed to model the hot ductility of the severe plastic deformed AA6061 alloy.

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“…Nevertheless, Nitinol 60 alloy exhibits poor workability attributed to the presence of considerable amount of intermetallic phases. [4][5][6] As a matter of course, how to find a way to predict and analyze the deformation behavior under different thermomechanical conditions is the primary concern in this regard.…”

Section: Introductionmentioning

confidence: 99%

A comparative study on constitutive equations and artificial neural network model to predict high-temperature deformation behavior in Nitinol 60 shape memory alloy

Shu

Wang

et al. 2015

J. Mater. Res.

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The present study was conducted to predict the hot deformation behavior of the as-forged Nitinol 60 shape memory alloy by using the Arrhenius type, multiple-linear, and artificial neural network (ANN) models. The acquired flow stress data from isothermal hot compression tests in a temperature range of 650-850°C under strain rate range of 0.01-1 s À1 were used to calculate the material constants for establishing the corresponding constitutive equations. Furthermore, a comparative study has been made on the capability of the aforementioned models to predict the high-temperature deformation behavior by comparing the prediction relative errors, average absolute relative error, and correlation coefficient. The results show that multiple-linear model predicts the flow behavior more accurately than the Arrhenius type model. The ANN model is much more efficient and has a better prediction power for the as-forged Nitinol 60 alloy than both the Arrhenius type and multiple-linear models.

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Microstructural Evolution During the Hot Deformation of Ti-55Ni (at. pct) Intermetallic Alloy

Cited by 27 publications

References 17 publications

Optimization of hot working parameters of as-forged Nitinol 60 shape memory alloy using processing maps

Optimization of hot working parameters of as-forged Nitinol 60 shape memory alloy using processing maps

Modeling the Hot Ductility of AA6061 Aluminum Alloy After Severe Plastic Deformation

A comparative study on constitutive equations and artificial neural network model to predict high-temperature deformation behavior in Nitinol 60 shape memory alloy

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