Orientation dependence of stress-induced phase transformation and dislocation plasticity in NiTi shape memory alloys on the micro scale

Pfetzing‐Micklich, Janine; Ghisleni, R.; Simon, T.; Somsen, Christoph; Michler, Johann; Eggeler, Gunther

doi:10.1016/j.msea.2012.01.042

Cited by 67 publications

(23 citation statements)

References 42 publications

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“…The development of recrystallization processes is also favored by the enhancement of volume diffusion in elastic strain fields and pulsed irradiation-induced temperature increase. The above results check well with the previously obtained evidence that the anisotropy of NiTi alloy plays a significant role in the development of deformation structure [7].…”

Section: Meso-and Microstructuresupporting

confidence: 92%

Structure of the near-surface layer of NiTi on the meso- and microscale levels after ion-beam surface treatment

Meisner¹,

Poletika

Meisner

et al. 2014

AIP Conference Proceedings

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Abstract. Using the EBSD, SEM and TEM methods, the structure of surface layer of polycrystalline NiTi alloy samples was examined after the modification of material surface by the pulsed action of mean-energy silicon ion beam. It was found that the ion beam treatment would cause grain fragmentation of the near-surface layer to a depth 5÷50 m; a higher extent of fragmentation was observed in grains whose close-packed planes were oriented approximately in the same direction as the ion beam was. The effect of high-intensity ion beam treatment on the anisotropic behavior of polycrystalline NiTi alloy and the mechanisms involved were also examined.

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Section: Meso-and Microstructuresupporting

confidence: 92%

Structure of the near-surface layer of NiTi on the meso- and microscale levels after ion-beam surface treatment

Meisner¹,

Poletika

Meisner

et al. 2014

AIP Conference Proceedings

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“…A possible mechanism by which transformation and micro-plasticity may evolve in a multi-grain environment during the cyclic superelasticity is presented in Figure 6 (adapted from [29] Thanks to rigorous electron microscopy studies, the exact nature of the dislocation slip structures as well as the predominant slip systems have been identified. Figure 7 provides several examples of TEM evidence of dislocation in the austenitic phase of NiTi SMA based on the references [9,11,23,32,101,114]. Similarly, martensitic slip in NiTi was reported by some studies [115,116] as shown.…”

Section: Experimental Observationsmentioning

confidence: 56%

“…The fact that the macroscale plastic yielding is not indicative of the actual initiation of dislocation activities points to the mesoscale factors [31,32]. For instance, local preferential sites such as grain boundaries, triple joints may pave the way for reaching high localized stress conducive to dislocation slip.…”

Section: Table Of Contentsmentioning

confidence: 99%

A revisit to atomistic rationale for slip in shape memory alloys

Chowdhury

Şehitoğlu

2017

Progress in Materials Science

120

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Performance degradation in shape memory alloys (SMA) arises due to a gradual loss of strain recoverability attributable to slip mediated plasticity. The slip-induced changes in SMAs can be profound creating accumulation of permanent strains, altering the critical stress and hysteresis in an adverse manner. Slip nucleation in ordered SMA lattices can often be triggered due to energetically favorable dissociation reactions. Partial slip can dominate over full slip, generating planar defects (e.g. anti-phase boundary, superlattice or complex stacking faults) as evidenced through electron microscopy. Considerable advances are made lately on physically rationalizing the observed plastic micromechanism(s) benefitting from quantum mechanical models. In-depth analyses of crystal variables (e.g. lattice ordering, atomic stacking and stable/metastable fault structures) subjected to intrinsic solid-state effects have unequivocally established the genesis of empirical slipping propensity in terms of atomic fault energetics. This article systematically revisits the empirical physical evidence of slip in important SMAs from the literature, presents the pertinent experimental findings, and then embarks on reviewing the

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“…Slip systems for plastic deformation can be directly observed 30 without secondary imaging. Video of various transitions such as phase transformations, 33 glass transitions, 31 deformation twinning, or various chemical reactions can all be directly observed and recorded. Fracture behavior, crack lengths, and ductile-brittle transformations can all also be observed.…”

Section: Introductionmentioning

confidence: 99%

Elevated temperature, nano-mechanical testing in situ in the scanning electron microscope

Wheeler

Michler

2013

Review of Scientific Instruments

Self Cite

138

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A general nano-mechanical test platform capable of performing variable temperature and variable strain rate testing in situ in the scanning electron microscope is described. A variety of test geometries are possible in combination with focused ion beam machining or other fabrication techniques: indentation, micro-compression, cantilever bending, and scratch testing. The system is intrinsically displacement-controlled, which allows it to function directly as a micro-scale thermomechanical test frame. Stable, elevated temperature indentation∕micro-compression requires the indenter tip and the sample to be in thermal equilibrium to prevent thermal displacement drift due to thermal expansion. This is achieved through independent heating and temperature monitoring of both the indenter tip and sample. Furthermore, the apex temperature of the indenter tip is calibrated, which allows it to act as a referenced surface temperature probe during contact. A full description of the system is provided, and the effects of indenter geometry and of radiation on imaging conditions are discussed. The stabilization time and temperature distribution throughout the system as a function of temperature is characterized. The advantages of temperature monitoring and thermal calibration of the indenter tip are illustrated, which include the possibility of local thermal conductivity measurement. Finally, validation results using nanoindentation on fused silica and micro-compression of [100] silicon micro-pillars as a function of temperature up to 500 °C are presented, and procedures and considerations taken for these measurements are discussed. A brittle to ductile transition from fracture to splitting then plastic deformation is directly observed in the SEM for silicon as a function of temperature.

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Orientation dependence of stress-induced phase transformation and dislocation plasticity in NiTi shape memory alloys on the micro scale

Cited by 67 publications

References 42 publications

Structure of the near-surface layer of NiTi on the meso- and microscale levels after ion-beam surface treatment

Structure of the near-surface layer of NiTi on the meso- and microscale levels after ion-beam surface treatment

A revisit to atomistic rationale for slip in shape memory alloys

Elevated temperature, nano-mechanical testing in situ in the scanning electron microscope

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