Asymmetry of stress–strain curves under tension and compression for NiTi shape memory alloys

Liu, Yong; Xie, Zhenghua; Humbeeck, Jan Van; Delaey, L.

doi:10.1016/s1359-6454(98)00112-8

Cited by 325 publications

(168 citation statements)

References 12 publications

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“…Like in Stage I, the change between Stage II to III in the dynamic compression experiment is less distinct due to the heterogeneous nature of deformation during dynamic loading likely resulting in both martensite reorientation and martensite elasto-plastic deformation, the latter being less present in the quasi-static compression experiment. [45] The change in slope is markedly different in Stage III between the quasi-static and dynamic compression experiments, where the slope of the dynamic compression experiment is much steeper (48.9 GPa) as compared to the quasi-static compression experiment (26.5 GPa). The point at which the quasi-static compression sample reaches Stage IV appears to be at around 1170 MPa (6 pct strain) and continues in Stage IV to about 1550 MPa (9.5 pct strain) before unloading.…”

Section: Resultsmentioning

confidence: 95%

“…There is no twin relation between neighboring martensite variants after compression because of the generation and movement of lattice defects. [43][44][45][46] The mechanical behaviors are nearly the same before the plastic deformation of reoriented martensite under quasi-static compression and dynamic compression, and the plastic stress level under dynamic loading is 500 MPa higher than that under quasi-static compression. [47] NiTi SMAs also exhibit a dynamic sensitivity.…”

Section: Introductionmentioning

confidence: 94%

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Influence of Dynamic Compression on Phase Transformation of Martensitic NiTi Shape Memory Alloys

Qiu

Young

Nie

2015

Metall Mater Trans A

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Shape memory alloys (SMAs) exhibit high damping capacity in both austenitic and martensitic phases, due to either a stress-induced martensite phase transformation or a stress-induced martensite variant reorientation, making them ideal candidates for vibration suppression devices to protect structural components from damage due to external forces. In this study, both quasi-static and dynamic compression was conducted on a martensitic NiTi SMA using a mechanical loading frame and on a Kolsky compression bar, respectively, to examine the relationship between microstructure and phase transformation characteristics of martensitic NiTi SMAs. Both endothermic and exothermic peaks disappear completely after experiencing deformation at a strain rate of 10 3 s À1 and to a strain of about 10 pct. The phase transformation peaks reappear after the deformed specimens were annealed at 873 K (600°C) for 30 minutes. As compared to samples from quasi-static loading, where a large amount of twinning is observed with a small amount of grain distortion and fracture, samples from dynamic loading show much less twinning with a larger amount of grain distortion and fracture.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 94%

Influence of Dynamic Compression on Phase Transformation of Martensitic NiTi Shape Memory Alloys

Qiu

Young

Nie

2015

Metall Mater Trans A

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“…With increasing strain (region II), a broad stress plateau is obtained where the deformation is mainly dominated by variant reorientation and detwinning of the initial [011] type II and (1 11) type I twinning modes. [29][30][31] In this same region, it has been reported that dislocation networks form in both the martensite twin plates 32 and in the junction plane areas 33 to accommodate the strain mismatch during variant reorientation. Further straining results in region III of rapid strain hardening, which is attributed to further reorientation and detwinning, the operation of new (20 1) and (100) deformation twins 30,31,34 and plasticity.…”

Section: Introductionmentioning

confidence: 88%

Role of B19′ martensite deformation in stabilizing two-way shape memory behavior in NiTi

Benafan

Padula

Noebe

et al. 2012

Journal of Applied Physics

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Deformation of a B19′ martensitic, polycrystalline Ni49.9Ti50.1 (at. %) shape memory alloy and its influence on the magnitude and stability of the ensuing two-way shape memory effect (TWSME) was investigated by combined ex situ mechanical experimentation and in situ neutron diffraction measurements at stress and temperature. The microstructural changes (texture, lattice strains, and phase fractions) during room-temperature deformation and subsequent thermal cycling were captured and compared to the bulk macroscopic response of the alloy. With increasing uniaxial strain, it was observed that B19′ martensite deformed by reorientation and detwinning with preferred selection of the (1¯50)M and (010)M variants, (201¯)B19′ deformation twinning, and dislocation activity. These mechanisms were indicated by changes in bulk texture from the neutron diffraction measurements. Partial reversibility of the reoriented variants and deformation twins was also captured upon load removal and thermal cycling, which after isothermal deformation to strains between 6% and 22% resulted in a strong TWSME. Consequently, TWSME functional parameters including TWSME strain, strain reduction, and transformation temperatures were characterized and it was found that prior martensite deformation to 14% strain provided the optimum condition for the TWSME, resulting in a stable two-way shape memory strain of 2.2%. Thus, isothermal deformation of martensite was found to be a quick and efficient method for creating a strong and stable TWSME in Ni49.9Ti50.1.

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“…[3] As a consequence, the study of the deformation and fracture behavior of Nitinol and its composites under various loading conditions becomes critical for the large-scale utilization of Nitinol. The mechanical response of Nitinol has been extensively studied experimentally and theoretically, at both quasistatic [10][11][12][13][14][15][16][17] and high strain rates. [18][19][20][21][22][23] However, the utilization and the potential application of Nitinol in long-life components as a structural material requires a thorough understanding of the dominant deformation and fracture mechanisms of Nitinol under different loading conditions.…”

Section: Introductionmentioning

confidence: 99%

Fracture of Nitinol under Quasistatic and Dynamic Loading

Jiang

Vecchio

2007

Metall Mater Trans A

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Owing to the potential application of Nitinol as an advanced structural material, it is essential to thoroughly understand the deformation and fracture behavior of Nitinol under various loading conditions. The present study explores the fracture behavior of Nitinol under quasistatic and dynamic loading, with emphasis on the fracture toughness and fracture mechanism of Nitinol. To this end, the precracked bend sample was employed to perform dynamic fracture testing using a modified (pulse-shaped) Hopkinson-pressure-bar-loaded fracture-testing system. The dynamic fracture initiation toughness was measured under stress-state equilibrium conditions at a loading rate of $ 10 6 MPa ffiffiffiffi m p /s. To further investigate the fracture mechanism, additional dynamic fracture tests were performed using double-crack, four-point bend samples. The experimental results indicate that the dynamic fracture toughness of Nitinol is higher than it is under quasistatic loading, and that the loading rate influences the fracture mechanisms of Nitinol. The interplay between the dynamic strength of Nitinol and the activation stress for stress-induced martensite (SIM) transformation plays an important role in the fracture behavior of Nitinol.

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Asymmetry of stress–strain curves under tension and compression for NiTi shape memory alloys

Cited by 325 publications

References 12 publications

Influence of Dynamic Compression on Phase Transformation of Martensitic NiTi Shape Memory Alloys

Influence of Dynamic Compression on Phase Transformation of Martensitic NiTi Shape Memory Alloys

Role of B19′ martensite deformation in stabilizing two-way shape memory behavior in NiTi

Fracture of Nitinol under Quasistatic and Dynamic Loading

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