What is the Limit of Nanoparticle Strengthening?

MRS Bulletin ◽  
2009 ◽  
Vol 34 (3) ◽  
pp. 173-177 ◽  
Author(s):  
D.C. Chrzan ◽  
J.W. Morris ◽  
Y.N. Osetsky ◽  
R.E. Stoller ◽  
S.J. Zinkle
Keyword(s):  
Nuclear Reactor ◽  
Matrix Material ◽  
Dislocation Motion ◽  
Perfect Crystal ◽  
Atomic Scale ◽  
Ideal Strength ◽  
Deformation Processes ◽  
Precipitate Strengthening ◽  
Transportation Applications ◽  
The Ideal

AbstractThe stress required to deform a perfect crystal to its elastic limit while maintaining perfect periodicity, the so-called ideal strength, sets the gold standard for the strength of a given material. Materials this strong would be of obvious engineering importance, potentially enabling more efficient turbines for energy production, lighter materials for transportation applications, and more reliable materials for nuclear reactor applications. In practice, the strength of engineering materials is often more than two orders of magnitude less than the ideal strength due to easily activated deformation processes involving dislocations. For many materials, precipitate strengthening is a promising approach to impede dislocation motion and thereby improves strength and creep resistance. This observation begs the question: What are the limits of nanoparticle strengthening? Can the ideal strength of a matrix material be reached? To answer these questions, we need a detailed, atomic scale understanding of the interactions between dislocations and obstacles. Fortunately, simulations are beginning to explore this interaction.

scholarly journals An independent derivation and verification of the voids nucleation failure mechanism: significance for materials failure

2019 ◽  
Vol 475 (2222) ◽  
pp. 20180755 ◽  
Author(s):  
Richard Christensen ◽  
Zhi Li ◽  
Huajian Gao
Keyword(s):  
Stress State ◽  
Failure Mechanism ◽  
Density Functional ◽  
Failure Modes ◽  
Shear Bands ◽  
Failure Criteria ◽  
Atomic Scale ◽  
Ideal Strength ◽  
Failure Theory ◽  
The Ideal

Independent derivations are given for the failure criteria of the purely dilatational stress state involving voids nucleation failure as well as for the purely distortional stress state involving shear bands failure. The results are consistent with those from a recently derived failure theory and they further substantiate the failure theory. The voids nucleation mechanism is compared with the ideal theoretical strength of isotropic materials as derived by density functional theory and two other atomic-scale methods. It is found that a cross-over occurs from the voids nucleation failure mechanism to the ideal strength limitation as the tensile to compressive strengths ratio, T / C , increases toward a value of unity. All the results are consistent with the failure modes transition results from the general failure theory.

Ideal Strength of Nano-Components

2005 ◽  
Vol 482 ◽  
pp. 25-32 ◽  
Author(s):  
Takayuki Kitamura ◽  
Yoshitaka Umeno ◽  
Akihiro Kushima
Keyword(s):  
High Strength ◽  
Perfect Crystal ◽  
The Other ◽  
Ideal Strength ◽  
Structured Materials ◽  
Recent Developments ◽  
Definition Of ◽  
Nano Wires ◽  
External Loads ◽  
The Ideal

The ideal (theoretical) strength was originally defined as the stress or strain at which perfect crystal lattice became mechanically unstable with respect to arbitrary homogeneous infinitesimal deformation. This has been intensely investigated because the ultimate strength without defects is a fundamental mechanical characteristic of materials. In the analyses, the instability criteria have been studied on the basis of elastic constants. Recent developments in computational technology make it possible to analyze the ideal strength on the basis of quantum mechanics. On the other hand, it is well known that the mechanical strength of components is dependent not only on (1) material (atom species), but also on (2) loading condition and (3) structure. Because most studies on the strength in terms of atomic mechanics have focused on the factor (1) (materials), analysis has mainly been conducted on simple crystal consisting of perfect lattices (e.g. fcc and bcc) under simple loading conditions (e.g. tension), though some have explored the properties of bulk materials with defects (e.g. vacancy and grain boundary). Small atomic components (nano-structured components) such as nano-films, nano-wires (tubes) and nano-dots (clusters) possess their own beautiful, defect-free structures, namely ideal structure. Thus, they show characteristic high strength. Moreover, utilizing the structure at the nanometer or micron level is a key technology in the development of electronic devices and elements of micro (nano) electro-mechanical systems (MEMS/NEMS). Therefore, it is important to understand the mechanical properties not only for the sake of scientific interest, but also for engineering usefulness such as design of fabrication/assembly processes and reliability in service. In the other words, the effects of structure (factor (3); e.g. film/wire/dot) have to be understood as the basic properties of atomic components. Thus, the definition of ideal strength should be expanded to include the strength at instability of components with ideal structures under various external loads (factor (2)), which provides fundamental knowledge of nano-structured materials. In this paper, we review works on the strength of ideal nano-structured components in terms of factor (3), mainly under tension.

Processing of Nanoporous Gold by Dealloying and its Morphological Control

2007 ◽  
Vol 561-565 ◽  
pp. 1657-1660 ◽  
Author(s):  
Masataka Hakamada ◽  
Mamoru Mabuchi
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Acid Treatment ◽  
Nanoporous Gold ◽  
Anisotropic Structure ◽  
Ideal Strength ◽  
Pore Characteristics ◽  
Very High ◽  
Ligament Size ◽  
The Ideal

Nanoporous gold was fabricated by dealloying and their pore characteristics were further modified by thermal or acid treatment. The fabricated nanoporous gold had a ligament size of approximately 5 nm. Thermal treatment on the nanoporous gold increased the ligament size to approximately 500 nm. During the thermal treatment, ligaments are bonded across the cracks which had been generated during the dealloying. Acid treatment also increased the ligament size to approximately 500 nm; however, the acid treatment had a different effect on the pore characteristics from the thermal treatment. As a result, nanoporous gold prism microassembly with anisotropic structure was spontaneously fabricated by the acid treatment. The mechanical properties of nanoporous gold were also examined. It is estimated that the yield strength of nanosized ligaments in nanoporous gold is very high and close to the ideal strength of gold.

Ageing Precipitate Strengthening of Cu-Containing Structural Steels

2011 ◽  
Vol 399-401 ◽  
pp. 144-147
Author(s):  
Hai Yan Wang ◽  
Hui Ping Ren ◽  
Zong Chang Liu
Keyword(s):  
High Purity ◽  
Metastable Phase ◽  
Ferrite Matrix ◽  
Dislocation Motion ◽  
Microstructure Observation ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
Relationship Of ◽  
Precipitate Strengthening ◽  
Observation Results

Microstructure evolution of Fe-1.18%Cu high purity steels during solution and aging was investigated under high-resolution electron microscope (HREM). In addition, the aging strengthening mechanisms were discussed based on the microstructure observation. The results show that there were lots of Cu atom clusters in ferrite matrix during solid solution and aging initial stages, subsequently, Cu-rich metastable Fe-Cu particles precipitate at the aging strength peak. It is found that the intense strengthening is controlled by the coherency relationship of Fe-Cu metastable phase with matrix that forms the obstacle of the dislocation motion, while the decrease of strength after the peak is attributed to the loss of coherency, which should highly likely be the dominant reason of aging strengthening in Cu bearing high purity steels Thus our TEM observation results are in reasonably agreement with some previous assume.

On the Ideal Strength of Crystals

1989 ◽  
Vol 151 (1) ◽  
pp. 85-93 ◽  
Author(s):  
J. Pokluda ◽  
P. Šandera
Keyword(s):  
Ideal Strength ◽  
The Ideal

Mechanical Properties of Superhard Nanocomposites with High Thermal Stability

2003 ◽  
Vol 791 ◽  
Author(s):  
Stan Veprek ◽  
Ali S. Argon
Keyword(s):  
Elastic Recovery ◽  
High Hardness ◽  
Phase Segregation ◽  
Grain Boundary Sliding ◽  
Structural Flexibility ◽  
Ideal Strength ◽  
Crystallite Sizes ◽  
Boundary Sliding ◽  
Plastic Transformation ◽  
The Ideal

Abstract Superhard nanocomposites, nc-MnN/a-XxNy (M = Ti, W, V, Zr, (Al1-xTix)N; X = Si, B) with hardness of 40–100 GPa are prepared by plasma CVD or PVD under a sufficiently high nitrogen activity and deposition temperature that allow the formation of a stable nanostructure by self-organization upon strong thermodynamically driven, spinodal phase segregation. These nanocomposites display an extraordinary combination of a high hardness, high elastic recovery, high resistance against brittle fracture and tensile strength of 5 to 40 GPa approaching the ideal strength of flaw-free materials. These properties can be understood in terms of conventional fracture physics scaled appropriately down to crystallite sizes of few nm. The interfacial monolayer of Si3N4 or BN with strong bonding to the nanocrystallites and high structural flexibility avoids grain boundary sliding. With increasing thickness of this interface the hardness decreases, possibly due to an increase of this “liquid-like” component in which plastic transformation can be triggered.

The mechanical properties of perfect crystals I. The ideal strength

1972 ◽  
Vol 330 (1582) ◽  
pp. 291-308 ◽  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Shear Strength ◽  
Sodium Chloride ◽  
Room Temperature ◽  
Cleavage Plane ◽  
Ideal Strength ◽  
Lennard Jones ◽  
Computer Calculations ◽  
The Ideal

In this paper we present computer calculations of the ideal strength of crystals of sodium chloride and argon, for a variety of modes of homogeneous deformation. As models of the interatomic binding we employ the simple, two-body, central-force Born-Mayer and Lennard-Jones potentials respectively. The calculations for argon are appropriate to absolute zero, those for sodium chloride to room temperature. The results indicate a very marked anisotropy of the ideal tensile strength for sodium chloride, with a pronounced minimum at <100>, which is consistent with the observed cleavage on this plane. The ideal tensile strength of argon is shown to be much less dependent on orientation, which accords with the lack of any obvious cleavage plane in this material. We also make some estimates of the ideal shear strength, and find this to be a minimum for {111} <112> shear for both argon and sodium chloride.

THE STABILITY OF FCC CRYSTAL Cu UNDER UNIAXIAL LOADING IN [001] DIRECTION

2009 ◽  
Vol 23 (15) ◽  
pp. 1871-1880 ◽  
Author(s):  
X. M. LIU ◽  
Z. L. LIU ◽  
X. C. YOU ◽  
J. F. NIE ◽  
Z. ZHUANG
Keyword(s):  
Hydrostatic Stress ◽  
Element Model ◽  
Uniaxial Loading ◽  
Ideal Strength ◽  
Anisotropic Character ◽  
Tension And Compression ◽  
Loading Tests ◽  
The Stability ◽  
Critical Resolved Shear Stress ◽  
The Ideal

Uniaxial loading tests of copper with inter-atomic potential finite-element model are carried out to determine the corresponding ideal tension and compression strength using the modified Born stability criteria. The influence of biaxial stresses applied perpendicularly to the [100] loading axis, on the ideal strength is investigated, and tension-compression asymmetry in ideal strength under [100] loading is also studied. The results suggest that asymmetry for yielding strength of [100] nanowires may result from anisotropic character of crystal instability. Moreover, the results also reveal that the critical resolved shear stress in the direction of slip is not an accurate criterion for the ideal strength since it cannot capture the dependence on the loading conditions and hydrostatic stress components for the ideal strength.

Theoretical Calculations of the Ideal Strength of Ni, NiAl and Ni3Al in Tension and Shear

2018 ◽  
Vol 10 (10) ◽  
pp. 1420-1426 ◽  
Author(s):  
Zhiqin Wen ◽  
Yuhong Zhao ◽  
Huijun Li ◽  
Yongmei Zhang ◽  
Shuo Wang ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Ideal Strength ◽  
The Ideal
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