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

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.

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

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.

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.

Research and Application on Magnesium Slag

2011 ◽  
Vol 280 ◽  
pp. 208-211 ◽  
Author(s):  
Si Yu Wang ◽  
Li Guang Xiao ◽  
Qiang Zhou ◽  
Kai Xu ◽  
Bao Li Chen ◽  
...  
Keyword(s):  
Calcium Silicate ◽  
Cementitious Material ◽  
Good Combination ◽  
Phase Changes ◽  
Differential Analysis ◽  
Ideal Strength ◽  
Hydration Products ◽  
Hydrated Calcium Silicate ◽  
Hydrated Calcium ◽  
The Ideal

The content of water glass in accordance with the size of range is a major factor in magnesium slag strength. The microstructure of the block of orthogonal testing three shows network-like, acicular, cotton wool attached to each other, the main hydration products are calcium silicate hydrate, needle-like ettringite and CSH gel, just the good combination among the hydration products the cementitious material get the ideal strength value. From the view of differential analysis curve, Ca (OH) 2 decomposed when the temperature reaches 500 °C -540 °C, Ca (OH) 2 generated by the calcium component within the cementitious material reaction with alkali, and the Ca (OH) 2 will participate in the reaction of hydrated calcium silicate gel, and enhance strength of the test block. From the TG thermal analysis we can see that there is no water loss in the process, the performance of ofmineral phase changes and thermal stability are great.

scholarly journals The ideal strength of two-dimensional stanene may reach or exceed the Griffith strength estimate

Nanoscale ◽  
2017 ◽  
Vol 9 (21) ◽  
pp. 7055-7062 ◽  
Author(s):  
Zhe Shi ◽  
Chandra Veer Singh
Keyword(s):  
Two Dimensional ◽  
Ideal Strength ◽  
The Ideal

Charge-density analysis of 1-nitroindoline: refinement quality using free R factors and restraints

2011 ◽  
Vol 67 (3) ◽  
pp. 250-262 ◽  
Author(s):  
Bartosz Zarychta ◽  
Jacek Zaleski ◽  
Janusz Kyzioł ◽  
Zdzisław Daszkiewicz ◽  
Christian Jelsch
Keyword(s):  
Charge Density ◽  
Theoretical Calculations ◽  
Local Symmetry ◽  
Anisotropic Model ◽  
Rocket Fuel ◽  
Density Analysis ◽  
R Factors ◽  
Experimental Charge Density ◽  
Significant Attention ◽  
The Ideal

Nitramines and related N-nitro compounds have attracted significant attention owing to their use in rocket fuel and as explosives. The charge density of 1-nitroindoline was determined experimentally and from theoretical calculations. Electron-density refinements were performed using the multipolar atom formalism. In order to design the ideal restraint strategy for the charge-density parameters, R-free analyses were performed involving a series of comprehensive refinements. Different weights were applied to the charge-density restraints, namely the similarity between chemically equivalent atoms and local symmetry. Additionally, isotropic thermal motion and an anisotropic model calculated by rigid-body analysis were tested on H atoms. The restraint weights which resulted in the lowest values of the averaged R-free factors and the anisotropic H-atom model were considered to yield the best charge density and were used in the final refinement. The derived experimental charge density along with intra- and intermolecular interactions was analysed and compared with theoretical calculations, notably with respect to the symmetry of multipole parameters. A comparison of different refinements suggests that the appropriate weighting scheme applied to charge-density restraints can reduce the observed artefacts. The topological bond orders of the molecule were calculated.

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