Slip activity of persistent slip bands in polycrystalline nickel

Weidner, Anja; Beyer, Ralf-Eckhard; Blochwítz, C.; Holste, C.; Schwab, A.; Tirschler, W.

doi:10.1016/j.msea.2006.07.039

Cited by 54 publications

(26 citation statements)

References 17 publications

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“…Schwab et al [84] as well as Hollmann [85] performed half-cycle experiments on nickel single crystals at room temperature [81] and low temperatures [85] in order to study the slip activity of PSBs. Weidner et al [62][63][64] adopted this technique for the investigation on the cyclic slip activity of PSBs in polycrystalline nickel. The ECCI technique was complemented by EBSD and atomic force microscopy (AFM) for studying the half-cycle slip activity [84,85].…”

Section: Ecci and The Slip Activity Of Psbsmentioning

confidence: 99%

“…The ECCI technique was complemented by EBSD and atomic force microscopy (AFM) for studying the half-cycle slip activity [84,85]. Polycrystalline nickel with mean grain size of about 70 μm was cyclically deformed with low plastic strain amplitude up to 7500 cycles and 30,000 cycles, which correspond to 0.15 and 0.6 N f , respectively [62]. The ECCI micrographs in Figure 12 illustrate the appearance of typical dislocation arrangements with PSBs in a matrix of dislocation veins and bundles at 7500 cylces (a,b) and 30,000 cycles (c,d), respectively.…”

Section: Ecci and The Slip Activity Of Psbsmentioning

confidence: 99%

“…Imaging of PSBs by ECCI is mainly useful for the determination of parameters like dislocation wall thickness and channel width [102] or the dependence of the PSB formation on the crystallographic orientation and/or grain size [103] due to the good statistics, which can be achieved by this method. Another aspect for which the ECC imaging can be used is the investigation of the activation of cyclic slip within the PSBs [62]. For such investigations, the specimens were pre-deformed to a certain number of cycles (e.g.…”

Section: Ecci and The Slip Activity Of Psbsmentioning

confidence: 99%

“…It is vividly seen that only a small part is active and that no preferred place for the activation of cyclic slip exists in an already well-developed PSB. The visibility of activation of cyclic slip during hc deformation in ECC images allows a pre-screening of grains, which can be then later subjected to detailed measurements of the slip step height and width using AFM [62]. Knowing the crystallographic orientations from EBSD measurements, the local shear strain amplitude can be calculated for individual slip steps [64].…”

Section: Ecci and The Slip Activity Of Psbsmentioning

confidence: 99%

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Case studies on the application of high-resolution electron channelling contrast imaging – investigation of defects and defect arrangements in metallic materials

Weidner

Biermann

2015

Philosophical Magazine

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In 1967, Coates discovered the electron channelling contrast of backscattered electrons (BSEs) in scanning electron microscopy, and by this the possibility to investigate arrangements of lattice defects in deformed microstructures of materials. Since that time, a straightforward development of the scanning electron microscopes as well as of the electron channelling contrast technique took place. Nowadays, the performance of scanning electron microscopes is high enough that the resolution of electron channelling contrast imaging (ECCI) micrographs is comparable with conventional bright field transmission electron microscopy (TEM) micrographs. In the first part of the present paper, a historical review on the development of the ECCI technique starting from its discovery more than 45 years ago up to the combination with other advanced methods of scanning electron microscopy like electron backscatter diffraction or high-resolution selected area channelling patterning in the last few years is given. Major important investigations using this technique for the visualization of individual lattice defects like stacking faults (SFs) and dislocations or dislocation arrangements are chronologically summarized. The second part demonstrates that nowadays, ECCI micrographs taken in high-resolution scanning electron microscopes can be called high-resolution ECCI (HR-ECCI). It is shown that the resolution of individual SFs and dislocations in the HR-ECCI micrographs is comparable to that of conventional TEM (about 15 nm defect image width). Furthermore, the paper is demonstrating that HR-ECCI micrographs can be obtained for various types of materials after different mechanical loadings and different grain sizes ranging from large grain size of 500 μm (cast steel) down to less than 2 μm (γ-TiAl).

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Section: Ecci and The Slip Activity Of Psbsmentioning

confidence: 99%

Section: Ecci and The Slip Activity Of Psbsmentioning

confidence: 99%

Section: Ecci and The Slip Activity Of Psbsmentioning

confidence: 99%

Section: Ecci and The Slip Activity Of Psbsmentioning

confidence: 99%

See 2 more Smart Citations

Case studies on the application of high-resolution electron channelling contrast imaging – investigation of defects and defect arrangements in metallic materials

Weidner

Biermann

2015

Philosophical Magazine

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“…Again, these studies were mainly performed on copper crystals [52,[65][66][67][68] but more recently also on nickel single crystals [69,70] and polycrystals. [71,72] Thus, Watt et al [65] and Basinski et al, [66] using optical microscopy, concluded that slip steps generated in one half-cycle almost disappeared in the subsequent reverse half-cycle.…”

Section: B Cyclic Strain Localization and Irreversibility Of Cyclic mentioning

confidence: 99%

Cyclic Slip Irreversibilities and the Evolution of Fatigue Damage

Mughrabi

2009

Metall Mater Trans A

214

105

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In this article, the physical origin of fatigue crack initiation in ductile metals is discussed from a historical perspective. The main focus is to assess those cyclic slip irreversibilities in a microstructural sense that occur not only at the surface but also in the bulk at the dislocation scale and to show how they contribute to surface fatigue damage. The evolution of early fatigue damage, as evidenced experimentally in the last decades, is reviewed. The phenomenon of cyclic strain localization in persistent slip bands (PSBs) and models of the formation of extrusions, intrusions, and microcracks are discussed in detail. The predictions of these models are compared with experimental evidence obtained on mono-and polycrystalline face-centered-cubic (fcc) metals. In addition, examples of the evolution of fatigue damage in selected fcc solid solution alloys and precipitation-hardened alloys and in body-centered-cubic (bcc) metals are analyzed. Where possible, the cyclic slip irreversibilities p, defined as the fraction of plastic shear strain that is microstructurally irreversible, have been estimated quantitatively. Broadly speaking, p has been found to vary over orders of magnitude (0 < p < 1), being almost negligible at low loading amplitudes (high fatigue lives) and substantial at larger loading amplitudes (low fatigue lives).

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Moderne Methoden der Rasterelektronenmikroskopie

Weidner¹,

Biermann²

2014

Moderne Methoden Der WerkstoffprüFung

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Slip activity of persistent slip bands in polycrystalline nickel

Cited by 54 publications

References 17 publications

Case studies on the application of high-resolution electron channelling contrast imaging – investigation of defects and defect arrangements in metallic materials

Case studies on the application of high-resolution electron channelling contrast imaging – investigation of defects and defect arrangements in metallic materials

Cyclic Slip Irreversibilities and the Evolution of Fatigue Damage

Moderne Methoden der Rasterelektronenmikroskopie

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