The role of dislocations in the flow stress grain size relationships

Li, J. C. M.; Chou, Y. T.

doi:10.1007/bf02900225

Cited by 338 publications

(83 citation statements)

References 75 publications

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“…This is because that Equation (16) is proportional to shear modulus and the ranking of shear modulus of the three materials is the same as above ranking for the slope. Such dependence of the slope on shear modulus is consistent with previous theoretical work of micrograins and nanograins [16,32,33]. Although more dislocation reactions at the TB for each material in the table may be discovered later, the averaged value given here is expected as a reasonable evaluation for the slope of HallPetch relationship of the nanotwinned material.…”

Section: Evaluating Strengthening At Tbsupporting

confidence: 90%

Strengthening at nanoscaled coherent twin boundary in f.c.c. metals

Dao

Zhu

2014

Philosophical Magazine

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This paper analyses slip transfer at the boundary of nanoscaled growth twins in face-centred cubic (f.c.c.) metals for strengthening mechanism. The required stress for slip transfer, i.e. inter-twin flow stress, is obtained in a simple expression in terms of stacking fault energy and/or twin boundary (TB) energy, constriction energy and activation volume. For nanotwinned Al, Cu and Ni, inter-twin flow stress versus twin thickness remarkably shows Hall-Petch relationship. The Hall-Petch slope is rationalized for various reactions of screw and non-screw dislocations at the TB. Additionally, strengthening at the boundary of nanoscaled deformation twins in f.c.c. metals is analysed by evaluating required twinning stress. At small nanograin size, the prediction of deformation twin growth stress shows inverse grain-size effect on twinning, in agreement with recent experimental finding.

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Section: Evaluating Strengthening At Tbsupporting

confidence: 90%

Strengthening at nanoscaled coherent twin boundary in f.c.c. metals

Dao

Zhu

2014

Philosophical Magazine

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“…However, pile-up is not always observed in experiment (e.g. Li and Chou, 1970) nor in three-dimensional DDD. Simulations of bicrystals under uniaxial loading (Daveau, 2012) have shown that grain boundaries do not, of themselves, cause pile-up.…”

Section: Theories Of the Inverse-square-root Dependencementioning

confidence: 97%

Grain size dependence of the strength of metals: The Hall–Petch effect does not scale as the inverse square root of grain size

Dunstan

Bushby

2014

International Journal of Plasticity

171

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“…HP considering that the fresh Frank-Read type source lies inside the new grain. Li [29] proposed instead that grain boundary ledges acted as the sources for dislocations in the undeformed grain. This concept was subsequently modified [30 and 31] by suggesting that geometrically necessary dislocations were created near grain boundaries where the deforming grain interior evolved to the undeforming grain boundary region.…”

Section: Strength Variation With Grain Size In Conventional Polycrys mentioning

confidence: 99%

The origins of strengthening in nanostructured metals and alloys

Morris¹

2010

REVMETAL

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Nanostructured metals and alloys have a variety of chemical and physical properties that are greatly modified by the nano-scale of their microstructure. At the same time, these materials generally show very high strength, although ductility or toughness may not be good. Strength increases as the microstructure scale reduces from the macro-micro level and even finer, but sometimes the strength appears to fall as the structure scale approaches the nano level. These strength variations are examined here, and the mechanisms responsible for both strengthening and weakening are discussed. The fall in ductility and toughness as materials become nanostructured is a complex topic that requires extensive analysis, but this will not be treated in the present overview. KeywordsNanomaterials; Mechanical properties; Strength; Grain size; Hall-Petch strengthening. El origen del endurecimiento de metales y aleaciones nanoestructurados ResumenLos metales y aleaciones nanoestructuradas muestran una serie de propiedades químicas y físicas fuertemente modificadas cuando su microestructura entra en la escala nano. A la vez, estos materiales muestran generalmente alta resistencia pero mediocre ductilidad o tenacidad. La resistencia aumenta cuando baja la escala de la microestructura desde el nivel micro hacia el nivel nano, pero a veces la resistencia parece reducir por las microestructuras mas finas. Se examinan aquí todas estas variaciones y se discuten los mecanismos responsables del endurecimiento y ablandamiento. Los cambios de ductilidad o tenacidad cuando la microestructura entra en la escala nano necesitan un aná-lisis detallado que no se trata en este articulo.

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The role of dislocations in the flow stress grain size relationships

Cited by 338 publications

References 75 publications

Strengthening at nanoscaled coherent twin boundary in f.c.c. metals

Strengthening at nanoscaled coherent twin boundary in f.c.c. metals

Grain size dependence of the strength of metals: The Hall–Petch effect does not scale as the inverse square root of grain size

The origins of strengthening in nanostructured metals and alloys

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