Mechanically-induced grain coarsening in gradient nano-grained copper

Chen, Wei; You, Zhifeng; Tao, Nengguo; Jin, Zhihua; Lü, Lei

doi:10.1016/j.actamat.2016.12.006

Cited by 128 publications

(40 citation statements)

References 68 publications

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“…37) Similarly, a lower rate of mechanically induced grain growth was found for a reduction of testing temperatures, although the experiments were already performed at low homologous values. 74,79) For any prediction regarding the migration rate it is thus of interest to understand if a pure mechanically driven regime exists at all, or if thermal effects also need to be considered at comparably low testing temperatures, though their contribution may be limited.…”

Section: Effect Of Deformation Temperature On the Saturationmentioning

confidence: 99%

Saturation of Grain Refinement during Severe Plastic Deformation of Single Phase Materials: Reconsiderations, Current Status and Open Questions

Renk

Pippan

2019

Mater. Trans.

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Grain refinement of materials by severe plastic deformation, investigation and understanding of their properties and phenomena has been a subject of intensive research over the last three decades. Along with the invention and development of these processes it has been recognized, that grain refinement is not indefinite but stagnates for single phase materials. Accordingly, the minimum grain sizes achievable are in the range between 50 and 500 nm. Motivated to find ways to overcome these limitations, effort has been made to understand the reasons behind. Various processes were suggested to cause saturation of grain fragmentation. While all of these assumptions and models were not based on direct observations, recently in-situ approaches allowed significant progress in understanding microstructural evolution and the principle restoration processes during severe straining. It is the aim of this work to recap important earlier findings, reconsider proposed models and to present our current understanding of the processes limiting grain refinement upon severe straining. Further it will be discussed, that similar processes generally occur during deformation of such fine scaled materials. They do not only govern saturation of grain refinement during severe deformation but more important also the mechanical response and performance of these materials. This motivates an in-depth understanding and therefore open questions as well as discrepancies between various experiments will be deliberately highlighted to stimulate further research and thus progress within this area.

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Section: Effect Of Deformation Temperature On the Saturationmentioning

confidence: 99%

Saturation of Grain Refinement during Severe Plastic Deformation of Single Phase Materials: Reconsiderations, Current Status and Open Questions

Renk

Pippan

2019

Mater. Trans.

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“…Comparisons of fatigue results among GNG Cu, annealed CG Cu and CG Cu demonstrate that tensioncompression asymmetry of GNG Cu is closely correlated with the microstructure of GNG layer. One prominent feature of GNG surface layer is characterized by highdensity dislocations and curved GBs, similar to those observed in nanostructured metals prepared by severe plastic deformation [4]. Previous studies have shown that tension-compression asymmetry with a mean stress amplitude of 25-44 MPa is still detected in UFG Cu fatigued in strain-controlled low-cycle regime (N f < 10 5 cycles) [20].…”

Section: Resultsmentioning

confidence: 53%

“…Gradient nanograined (GNG) metals, as a promising hierarchical structure with grain sizes spatially increasing from nanoscale in surface to coarse grain (CG) in core, have attracted considerable interests, due to their unusual combination of high strength and considerable ductility in tensile tests [1][2][3][4]. Their fatigue properties and behaviours under cyclic loading are also very essential, which determine their prospect of engineering application [5].…”

Section: Introductionmentioning

confidence: 99%

Residual stress induced tension-compression asymmetry of gradient nanograined copper

Long

Pan

Tao

et al. 2018

Materials Research Letters

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The residual stress significantly influences the cyclic stress response of the hierarchical nanostructured materials. An obvious tension-compression asymmetry with minimum stress in compression larger than maximum stress in tension was observed in gradient nanograined (GNG) Cu under straincontrolled high-cycle fatigue tests, which gradually diminished with increasing cycles or after being annealed at a low temperature. The observed asymmetric response is primarily induced by the presence of the residual compressive stress in the GNG surface layer. The longer fatigue life can be achieved in GNG Cu with a higher residual stress, compared to that of annealed GNG Cu. IMPACT STATEMENT Obvious tension-compression asymmetry was observed in cyclically deformed gradient nanograined Cu under strain control, caused by the residual compressive stress in the GNG surface layer.

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“…With increasing rolling strain, an increase in the FWHM of the (111) diffraction peak is found in the majority of the deformed layers. Considering that stress-induced grain growth behavior is commonly observed in deformed nanostructured metals, even in the gradient microstructure [22,23], grain size should not increase FWHM values, and thus an increase in FWHM indicates dislocation accumulation in the deformed grains. It has also been observed that FWHM decreases in some deformed layers, especially in layers with small grain size.…”

Section: Resultsmentioning

confidence: 99%

Grain Orientation Induced Softening in Electrodeposited Gradient Nanostructured Nickel during Cold Rolling Deformation

Wang

et al. 2020

Reviews on Advanced Materials Science

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Quantitative microstructural evolution and the corresponding microhardness of electrodeposited nanostructured nickel sheet during cold rolling deformation are investigated by x-ray diffraction, transmission electron microscopy and Vicker’s microhardness testing. Particularly, to investigate the effect of stress states on deformation behavior, two series of gradient nanostructured nickel with symmetric structures and the homogeneous counterparts with three levels of grain size are compared based on macro-statistical data. In such hierarchical sandwich-like gradient samples, the layers with larger grain size, as the soft phase, indeed sustain more deformation. Deformation-induced grain rotation changes are observed in the center layers with a relatively larger grain size, accompanied by an obvious decrease in microhardness. According to the quantitative microstructural parameters including the grain size, dislocation density and stacking fault probability before and after deformation, evaluation based on Hall-Petch and Bailey-Hirsch relationships indicates the transition from strain hardening to softening can be attributed to grain orientation change.

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Mechanically-induced grain coarsening in gradient nano-grained copper

Cited by 128 publications

References 68 publications

Saturation of Grain Refinement during Severe Plastic Deformation of Single Phase Materials: Reconsiderations, Current Status and Open Questions

Saturation of Grain Refinement during Severe Plastic Deformation of Single Phase Materials: Reconsiderations, Current Status and Open Questions

Residual stress induced tension-compression asymmetry of gradient nanograined copper

Grain Orientation Induced Softening in Electrodeposited Gradient Nanostructured Nickel during Cold Rolling Deformation

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