Preface

Caillard, D.; Martin, Jean‐Luc

doi:10.1016/s1470-1804(03)80029-9

Cited by 105 publications

(168 citation statements)

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“…[32] The changes in Lankford coefficient with temperature shown in Figure 3 suggest that the difference in CRSS between hai and hc+ai slip increases with the temperature. Since twinning also contributes to the deformation strain and the amount of twinning changes with temperature, it could be argued that the increasing anisotropy is a consequence of lower twinning activity.…”

Section: A Mechanical Behavior: Effect Of Temperature and Loading DImentioning

confidence: 97%

Grain Breakup During Elevated Temperature Deformation of an HCP Metal

Honniball

Preuss

Rugg

et al. 2015

Metall Mater Trans A

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A combination of mechanical testing, EBSD and crystal plasticity finite element modeling were used to investigate the influence of temperature on the fragmentation of grains in a zirconium alloy. The results demonstrate that grains of Zircaloy-4 fragment more as the temperature rises. This trend can be explained by an increasing difference between the CRSS values for hc+ai slip and hai slip as temperature rises. This change in relative slip activities with temperature is supported by experimental observations of macroscopic anisotropy and in-grain misorientation axes calculated from EBSD data, as well as plasticity modeling. By tracking the microstructural evolution during deformation, it is shown that the two major texture components fragment to different degrees under the action of prismatic slip. Grains in the 1120 fiber are significantly more stable than those in the 1010 fiber, which break up. Grains of the latter fiber fragment heterogeneously as portions of the grain rotate in opposite directions, and some do not rotate at all.

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Section: A Mechanical Behavior: Effect Of Temperature and Loading DImentioning

confidence: 97%

Grain Breakup During Elevated Temperature Deformation of an HCP Metal

Honniball

Preuss

Rugg

et al. 2015

Metall Mater Trans A

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“…2B, Inset). The ratio Re = ρ m /ρ m0 represents the relative mobile dislocation density evolution (13). Fig.…”

Section: Unique Mechanical Responses Under Uniaxial Tensionmentioning

confidence: 99%

Extraordinary strain hardening by gradient structure

Jiang

Chen

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

1,045

415

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Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures.gradient structured metal | nanocrystalline metal M ankind has much to learn from nature on how to make engineering materials with novel and superior physical and mechanical properties (1, 2). For examples, the clay-polymer multilayers mimicking naturally grown seashells are found to have exceptional mechanical properties (3). Another example is the gradient structure, which exists in many biological systems such as teeth and bamboos. A typical gradient structure exhibits a systematic change in microstructure along the depth on a macroscopic scale. Gradient structures have been evolved and optimized over millions of years to make the biological systems strong and tough to survive nature. They are greatly superior to manmade engineering materials with homogeneous microstructures.Here we report the discovery of a hitherto unknown, to our knowledge, strain hardening mechanism, which is intrinsic to the gradient structure in an engineering material. The gradient structure shows a surprising extra strain hardening along with an up-turn and subsequent good retention of strain hardening rate. Strain hardening is critical for increasing the material ductility (4-6). We also show a superior ductility-strength combination in the gradient structure that is not accessible to conventional homogeneous microstructures. Microstructural Characterization of Gradient StructureWe demonstrate these behaviors in a grain-size gradient-structured (GS) sample, i.e., two GS surface layers sandwiching a coarse-grained (CG) core, produced by the surface mechanical attrition treatment (SMAT) (7) in a 1-mm-thick CG interstitial free (IF)-steel sheet (SI Materials and Methods). The GS layers on both sides have a gradual grain-size increase along the depth (Fig. 1A). In the outermost layer of ∼25-μm thickness are nearly equiaxial nanograins with a mean size of 96 nm (Fig. 1B). The grain size increases gradually to 0.5 and 1 μm at ...

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“…with an equivalent Schmid factor of 0.408 will be simultaneously activated. This multiple slip orientation is stable against lattice rotations and will induce a homogeneous dislocation distribution in the grain [39].…”

Section: Discussionmentioning

confidence: 99%

Deformation of an Al–7Mg alloy with extensive structural micro-segregations during dynamic plastic deformation

Jin

Tao

Marthinsen

et al. 2015

Materials Science and Engineering: A

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The microstructure evolution and deformation behavior of an as-cast Al-7Mg alloy with severe Mg segregation zones distributed on grain boundaries and in interdendrite regions subjected to dynamic plastic deformation (DPD) at both room and liquid nitrogen temperatures have been studied. At low strains, the deformation of the material is found to be mainly through the formation of deformation bands. At high strains, globular ultrafine grains form in the materials due to continuous dynamic recrystallization, which is also the dominant grain refinement mechanism. After deformation to strain of 1.0, the Mg segregation zones are deformed into fine parallel bands distributing along the deformation bands. Moreover, it is revealed that Al 8 Mg 5 particles and the Mg segregation can enhance the formation of deformation bands even in grains with a stable orientation, namely those with one of the {101} planes perpendicular to the compression direction, which can reduce the inhomogeneity of the deformation structure.2

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Preface

Cited by 105 publications

References 0 publications

Grain Breakup During Elevated Temperature Deformation of an HCP Metal

Grain Breakup During Elevated Temperature Deformation of an HCP Metal

Extraordinary strain hardening by gradient structure

Deformation of an Al–7Mg alloy with extensive structural micro-segregations during dynamic plastic deformation

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