Effects of heat treatment and ECAE process on transformation behaviors of TiNi shape memory alloy

Li, Zhenhua; Cheng, Xinbin; Shangguan, Qianqian

doi:10.1016/j.matlet.2004.08.039

Cited by 42 publications

(24 citation statements)

References 18 publications

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“…61 By contrast, only one endothermic peak is observed on heating which suggest a reverse R-phase transformation and a reverse martensitic transformation overlap. 62 Figure 12b shows the DSC curves of the specimen after two passes of ECAP at the high temperature of 823 K. 60 It was found there was only one broadened exothermic peak on the cooling curve and the B2 to R-phase transformation peak was not clearly defined but, at the same time, the transformation temperatures decreased sharply. These results confirm that processing of TiNi by SPD in high temperature ECAP affects the microstructural evolution in the alloy.…”

Section: Other Materialsmentioning

confidence: 99%

Using differential scanning calorimetry as an analytical tool for ultrafine grained metals processed by severe plastic deformation

Gao

Starink

Langdon

2009

Materials Science and Technology

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Differential Scanning Calorimetry (DSC) is a thermal analysis technique that measures the energy absorbed or released by a sample as a function of temperature or time. Analysis by DSC has wide applications for examining solid-state reactions and solid-liquid reactions in many different materials. Quantitative analyses of the kinetics of reactions may be assessed by reviewing the interrelation between activation energy analysis methods. In recent years, DSC has been applied in the examination and analysis of bulk ultrafine-grained materials processed through the application of Severe Plastic Deformation (SPD). This overview examines these recent reports with reference to materials processed using the procedures of Equal-Channel Angular Pressing (ECAP), High-Pressure Torsion (HPT) and Accumulative Roll-Bonding (ARB). In addition, some critical issues related to DSC analysis are also discussed.

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Section: Other Materialsmentioning

confidence: 99%

Using differential scanning calorimetry as an analytical tool for ultrafine grained metals processed by severe plastic deformation

Gao

Starink

Langdon

2009

Materials Science and Technology

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“…Using ECAE process [8][9][10][11][12][13][14][15][16] , some studies have been done in NiTi SMA with respect to microstructural characteristics related to the change of the direct (B2→B19') martensitic transformation to intermediate B2→R martensitic transformation.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, most of the literature discusses the martensitic transformation behavior in alloys deformed by ECAE in austenitic NiTi alloys 8,9,11,12,[14][15][16] and only a few works report on the martensitic NiTi alloys 10,13 . The present paper shows the results of martensitic NiTi alloy deformed by 1 ECAE pass and a correlation between microstructure, hardness and martensitic transformations temperatures.…”

Section: Introductionmentioning

confidence: 99%

ECAE processed NiTi shape memory alloy

et al. 2014

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The current work evaluated the microstructures and martensitic transformation temperatures of NiTi shape memory alloy (SMA) deformed by equal channel angular extrusion (ECAE). The Ti-55.27wt.%Ni alloy was processed by 1 ECAE pass at 250 °C using a die with an intersection angle of 120°. After processing, samples were annealed at 300 °C, 400 °C and 500 °C for 1h to evaluate the microstructural changes. Microstructural characterization was performed by scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS) device, and Vickers hardness measurement. Martensitic transformations temperatures were analyzed by differential scanning calorimetry (DSC). Results show that the annealing treatments presented no significant change in the microstructure of the ECAE processed samples. Meanwhile, the DSC curves corresponding to the annealing treatments performed at 300 °C and 400 °C show two step martensitic transformation related to B2→R→B19'. For the annealing at 500 °C, the martensitic transformation temperatures returned to the ST condition, indicating a reduction of the processing defects.

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“…The M;,) and M pz values changed slightly during heat-treatments above 873 K in the cooling process. Reverse martensitic transformation peak temperatures (A p ), A pz and A p3 ) of the specimens, which were annealed over 873 K, increased remarkably, compared with those annealed below 873 K. This dramatic increase in peak temperature of reverse martensitic transformation was implicitly due to re-crystallization (Li, et al, 2005;2006). The mechanism nanocrystalline structure under post-deformation annealing in a temperature range from 473 to 673 K (Khmelevskaya, et al, 2003a;2003b;Sergueeva, et al, 2003;Brailovski, et al, 2004).…”

Section: Effect Of Post-deformation Annealingmentioning

confidence: 93%

Effects of severe plastic deformation and heat treatment on transformation behavior of explosively welded duplex TiNi−TiNi

Zheng

Cui

2007

Pet. Sci.

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The effects of severe plastic deformation and heat treatment on the transformation behavior of explosively welded duplex TiNi-TiNi shape memory alloys (SMAs) were investigated by differential scanning calorimeter (DSC) measurements. The explosively welded duplex TiNi-TiNi plate of 0.7 mm thickness was cold-rolled at room temperature to a 60% reduction in thickness and then annealed at different temperatures for different durations. The results showed that low temperature (623-723K) heat-treatment led to the crystallization of the amorphous region, and re-crystallization occurred in the specimens annealed at higher temperatures (over 873 K). Research indicated that the change of martensitic transformation temperature is due to the change of internal stresses with increasing heat treatment temperature. The change of annealing time also led to a change in martensitic transformation temperature, which was associated with the precipitation and decomposition of Ti 3Ni4 in TiNi-l. Table 1 Transformation temperatures of original materialsSpecimens of 10 mmx l S mm were spark cut from the 0.7 mm thick sheet of explosively welded duplex TiNi-TiNi SMAs. They were cold rolled at room temperature to a 60% reduction in thickness. During the cold rolling, the duplex TiNi-TiNi sheets were sandwiched by stainless steel sheets to prevent fracture. After being cold rolled, the duplex sheet was submitted to various annealing treatments. A large range of annealing temperatures (from 573 to 973 K) and time durations (from 15 min to 10 h) were selected for the vacuum annealing under a pressure lower than 1.0xlO-2 Pa. The ExperimentalThe specimens used were explosively welded duplex TiNi-TiNi shape memory alloys. The two TiNi plates used for welding had dimensions of 200 mmx 100 mmx l mm. The chemical composition of TiNi-l was Ni-50.2 at% Ti and TiNi-2 was Ni-50 at% Ti. The transformation temperatures of these two TiNi plates measured with a differential scanning calorimeter (DSC) before welding are listed in Table 1, where M; M r , M p , As, A r and A p are the starting, finishing and peak temperatures of the martensitic and reverse martensitic transformation, respectively.

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Effects of heat treatment and ECAE process on transformation behaviors of TiNi shape memory alloy

Cited by 42 publications

References 18 publications

Using differential scanning calorimetry as an analytical tool for ultrafine grained metals processed by severe plastic deformation

Using differential scanning calorimetry as an analytical tool for ultrafine grained metals processed by severe plastic deformation

ECAE processed NiTi shape memory alloy

Effects of severe plastic deformation and heat treatment on transformation behavior of explosively welded duplex TiNi−TiNi

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