A model for the deformation of nanocrystalline materials

Hahn, Horst; Padmanabhan, K. A.

doi:10.1080/01418639708241122

Cited by 210 publications

(82 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Representing grains as rhombic dodecahedrons and considering rate controlled flow of grain boundaries, Hahn and Padmanabhan [80,81] derived an equation for the threshold stress needed for mesoscopic grain boundary sliding and studied the inverse Hall-Petch effect in nanomaterials.…”

Section: Grain Boundary Slidingmentioning

confidence: 99%

See 1 more Smart Citation

Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

Mishnaevsky

Левашов

2015

Computational Materials Science

View full text Add to dashboard Cite

Abstract:An overview of micromechanical models of strength and deformation behaviour of nanostructured and ultrafine grained metallic materials is presented. Composite models of nanomaterials, polycrystal plasticity based models, grain boundary sliding, the effect of nonequilibrium grain boundaries and nanoscale properties are discussed and compared. The examples of incorporation of peculiar nanocrystalline effects (like large content of amorphous or semi-amorphous grain boundary phase, partial dislocation GB emission/glide/GB absorption based deformation mechanism, diffusion deformation, etc.) into continuum mechanical approach are given. The possibilities of using micromechanical models to explore the ways of the improving the properties of nanocrystalline materials by modifying their structures (e.g., dispersion strengthening, creating non-equilibrium grain boundaries, varying the grain size distributions and gradients) are discussed.Keywords: Micromechanics; Finite element modelling; Nanomaterials; Nanocrystalline materials IntroductionDuring recent decades, growing interest of scientific community has been attracted to the nanostructured materials. The expectations on nanostructuring as a way to enhance material performances and to improve competing materials properties are very high, and some of them have been delivered, indeed.The extraordinary properties of nanocrystalline and ultrafine grained metallic materials (i.e., materials with the grain sizes of the order of several to several hundred nanometers) include superductility at room temperature, high hardness and high strength 2 to hardness value (which might be 2…7 times higher than in coarse grained materials), lower elastic modulus, negative Hall-Petch slope, enhanced strain rate sensitivity and difference between tensile and compression response [1][2][3][4][5]. The yield strength of nanocrystalline materials can be up to 5…10 times higher than of coarse-grained materials [6]. Other peculiar effect of nanocrystalline materials are the deviation fromHall-Petch relation at ultrafine and nanoscale grain sizes (below 100 nm), which goes into negative Hall Petch slope at about 10 nm, as well as asymmetry of tensile and compressive behaviour and enhanced diffusion properties [7].In order to predict the service properties of the materials and to explore the potential and reserves of their improvement, computational models linking the macroscale (service) In this paper, we present an overview of micromechanical models of nanocrystalline and ultrafine grained materials, their mechanical behaviour, deformation and strength.Composite models, crystal plasticity based models, grain boundary sliding, the effect of non-equilibrium grain boundaries, etc. are reviewed. The main constraints and challenges in the considered models are discussed. Composite models of nanocrystalline metallic materialsThe main structural feature of nanocrystalline and ultrafine grained materials, apart from the small grain sizes, is the high relative volume of grain boundary surface pha...

show abstract

Section: Grain Boundary Slidingmentioning

confidence: 99%

“…A number of computational models of the nanomaterial deformation are based on the analytical models from [72,73,80].…”

Section: Grain Boundary Slidingmentioning

confidence: 99%

Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

Mishnaevsky

Левашов

2015

Computational Materials Science

View full text Add to dashboard Cite

show abstract

“…[37] 3. Atomic scale boundary sliding model Hahn and Padmanabhan [38] developed a model for deformation in nc materials. The model is based on the concept that deformation in nc materials is controlled by atomic scale boundary sliding.…”

Section: Triple Junction Modelmentioning

confidence: 99%

Deformation Mechanisms in Nanocrystalline Materials

Mohamed

Yang

2009

Metall Mater Trans A

View full text Add to dashboard Cite

As a result of recent investigations on nanocrystalline (nc) materials, extensive experimental data on the deformation behavior of these materials have become available. In this article, an analysis of these data was performed to identify the requirements that a viable deformation mechanism should meet in terms of accounting for the mechanical characteristics and trends that are revealed by the data. The results of the analysis show that a viable deformation mechanism is required to account for the following: (1) an activation volume the value of which is in the range 10 to 40 b 3 ; (2) an activation energy that is close to the activation energy for boundary diffusion but that decreases with increasing applied stress; (3) the magnitudes of deformation rates that cover wide ranges of temperatures, stresses, and grain sizes; (4) inverse Hall-Petch behavior; and (5) limited ductility. The validity of available deformation mechanisms for nc materials is closely examined in the light of these requirements.

show abstract

“…An alternative process based on the formation of mesoscopic grain boundaries has been proposed for nanocrystalline materials. [35] By grain boundary migration the grain morphology is altered to produce a flat mesoscopic interface over the dimensions of many grain diameters. The threshold stress for the smoothening of the grain boundaries has been calculated and found to decrease with decreasing grain size, i.e., an opposite behavior as in materials with larger grain sizes.…”

Section: Nanoceramicsmentioning

confidence: 99%

Unique Features and Properties of Nanostructured Materials

Hahn¹

2003

Adv Eng Mater

Self Cite

View full text Add to dashboard Cite

In this introductory paper an attempt is made to give an overview of the area of nanostructured "materials irrespective of the synthesis process. The various microstructural features such as clusters or isolated nanoparticles, agglomerated nanopowders, consolidated nanomaterials and nanocomposite materials as well as all materials classes are considered. As an important component of modern research on nanomaterials a section describes the various characterization tools available. Based on these remarks some properties of nanostructured materials will be summarized emphasizing the property-microstructure relationships. Finally, a brief outlook on applications and initial industrial use of nanomaterials is presented. IntroductionNanostructures are plentiful in nature. In the universe nanoparticles are distributed widely and are considered to be the building blocks in planet formation processes. Biological systems have built up inorganic-organic nanocomposite structures to improve the mechanical properties or to improve the optical, magnetic and chemical sensing in living species. As an example, nacre (mother-of-pearl) from the mollusc shell is a biologically formed lamellar ceramic, which "exhibits structural robustness despite the brittle nature of its constituents.[1] Figure 1 shows an SEM imge of a fracture surface of an abalone shell exhibiting the CaCO 3 -platelets which are se-

show abstract

A model for the deformation of nanocrystalline materials

Cited by 210 publications

References 29 publications

Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

Micromechanical modelling of nanocrystalline and ultrafine grained metals: A short overview

Deformation Mechanisms in Nanocrystalline Materials

Unique Features and Properties of Nanostructured Materials

Contact Info

Product

Resources

About