Strain hardening in gradient nano-grained Cu at 77 K

Zhou, Xinzhe; Li, X.Y.; Lu, K.

doi:10.1016/j.scriptamat.2018.04.039

Cited by 33 publications

(14 citation statements)

References 21 publications

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“…Plastic accommodation, therefore, plays a crucial role in producing superior mechanical properties [3][4][5][6][26][27][28][29][30][31][32][33][34][35], as an inevitable reflection of heterogeneous deformation in response to strengthening (yield strength, σ y ) and subsequent strain hardening [36]. It remains unclear how heterogeneous tensile deformation proceeds in the GS.…”

Section: Introductionmentioning

confidence: 99%

Plastic accommodation during tensile deformation of gradient structure

Yang

et al. 2021

Sci. China Mater.

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Gradient structure (GS) possesses a typical trans-scale grain hierarchy with varying internal plastic stability, and the mutual plastic accommodation plays a crucial role in its superior strength-ductility combination. Using the in-situ synchrotron X-ray diffraction (XRD) during tensile loading, we measured lattice strains sequentially from the nanostructured (NS) surface layer to the central coarsegrained (CG) layer to elucidate when and how plastic accommodation occurs and evolves within the GS, along with their roles in plastic deformation and strain hardening. Throughout the tensile deformation, two types of plastic incompatibility occur in the GS. One is an extended elastoplastic transition due to layer-by-layer yielding. The other is strain localization and softening in the NS layer, in contrast with the stable plastic deformation in the CG layer. Plastic accommodation thus occurs concurrently and manifests as both an inter-layer and intra-layer change of stress state throughout tensile deformation. This produces different micromechanical responses between layers. Specifically, the NS layer initially experiences strain hardening followed by an elastoplastic deformation. The hetero-deformation induced hardening, along with forest hardening, facilitates a sustainable tensile strain in the NS layer, comparable to that in the CG layer.

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Section: Introductionmentioning

confidence: 99%

Plastic accommodation during tensile deformation of gradient structure

Yang

et al. 2021

Sci. China Mater.

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“…131 According to the Frank-Read-type source model, the critical size for the full-to-partial dislocation transition in plastic deformation was estimated to be about 70 nm in Cu. 132,133 In fact, a number of experimental observations verified that partial dislocations become a major strain carrier for very fine nanograins (e.g., below 10 nm for Ni-Mo alloys 114 ). Given the high excess energy of the grain-boundary network, it is reasonable to expect that equilibrium would favor deformation mechanisms that constructively interact with (i.e., decrease) that excess energy.…”

Section: Promoting Low-energy Grain-boundary Crystallographiesmentioning

confidence: 99%

Stability of nanocrystalline metals: The role of grain-boundary chemistry and structure

Schuh

2021

MRS Bulletin

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Nanocrystalline metals are transitioning from laboratory curiosities to engineering materials, in large part due to advances in improving their stability, making their exceptional properties more predictable and accessible. Nanoscale grains typically have a very strong innate tendency to coarsen, but the grain-boundary structure can be designed and tuned to lower its excess energy, reducing both the driving force for coarsening and the grain-boundary mobility. This article reviews two major strategies for achieving low-energy grain boundaries in nanocrystalline structures. First, grain-boundary alloying is discussed, including grainboundary segregation and its energetic competition with the formation of second phases; with sufficient grain-boundary segregation tendency it is possible to stabilize nanostructures to high temperatures. Second, methods of achieving low-energy crystallographic grainboundary structures are discussed, including the formation of nanotwinned structures and relaxing grain boundaries into low-energy structures through their interactions with partial dislocations. Both of these strategies have led to effective and implementable stable nanocrystalline materials, and point to many directions for future advancements.

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“…Further refining lamellae below the saturation size is challenging due to the increasing tendency of GB annihilation via dislocation annihilation and migration of GBs during straining [ 20 ]. By increasing strain rates and/or decreasing deformation temperature, grains of pure Cu can be refined to 40 nm [ 21 , 22 , 23 ] and even down to 10 nm [ 24 ]. However, the nanostructured Cu tends to show morphology of roughly equiaxed grains with plenty of twins and stacking faults rather than laminated structure as that in Ni [ 1 , 11 ] and Al [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to grain size, deformation conditions, such as temperature and strain rate, et al, also affect deformation mechanism significantly [ 23 ], which provides a possible way to generate NL structure in Cu with boundary spacing smaller than 200 nm. In our recent study about tension induced GBM in nanograined (NG) Cu [ 25 ], it has been found that full dislocation motion plays a key role in mechanically induced GBM and results in an increasing fraction of low angle GBs.…”

Section: Introductionmentioning

confidence: 99%

Formation of Nanolaminated Structure with Enhanced Thermal Stability in Copper

Hou

2021

Nanomaterials

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Nanolaminated structure with an average boundary spacing of 67 nm has been fabricated in copper by high-rate shear deformation at ambient temperature. The nanolaminated structure with an increased fraction of low angle grain boundaries exhibits a high microhardness of 2.1 GPa. The structure coarsening temperature is 180 K higher than that of its equiaxial nanograined counterpart. Formation of nanolaminated structure provides an alternative way to relax grain boundaries and to stabilize nanostructured metals with medium to low stacking faults energies besides activation of partial dislocations.

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Strain hardening in gradient nano-grained Cu at 77 K

Cited by 33 publications

References 21 publications

Plastic accommodation during tensile deformation of gradient structure

Plastic accommodation during tensile deformation of gradient structure

Stability of nanocrystalline metals: The role of grain-boundary chemistry and structure

Formation of Nanolaminated Structure with Enhanced Thermal Stability in Copper

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Strain hardening in gradient nano-grained Cu at 77 K

Cited by 33 publications

References 21 publications

Plastic accommodation during tensile deformation of gradient structure

Plastic accommodation during tensile deformation of gradient structure

Stability of nanocrystalline metals: The role of grain-boundary chemistry and structure

Formation of Nanolaminated Structure with Enhanced Thermal Stability in Copper

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Strain hardening in gradient nano-grained Cu at 77 K