Length Scale Effects in Materials Deformation of Nano and Microscale Au Structures

2009 ◽  
Author(s):  
Jie Lian ◽  
Junlan Wang
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Size Effect ◽  
Sample Size ◽  
Atomistic Simulation ◽  
Scale Effects ◽  
Elastic Recovery ◽  
Boundary Effect ◽  
Dislocation Nucleation ◽  
Atomistic Simulations

In this study, intrinsic size effect — strong size dependence of mechanical properties — in materials deformation was investigated by performing atomistic simulation of compression on Au (114) pyramids. Sample boundary effect — inaccurate measurement of mechanical properties when sample size is comparable to the indent size — in nanoindentation was also investigated by performing experiments and atomistic simulations of nanoindentation into nano- and micro-scale Au pillars and bulk Au (001) surfaces. For intrinsic size effect, dislocation nucleation and motions that contribute to size effect were analyzed for studying the materials deformation mechanisms. For sample boundary effect, in both experiments and atomistic simulation, the elastic modulus decreases with increasing indent size over sample size ratio. Significantly different dislocation motions contribute to the lower value of the elastic modulus measured in the pillar indentation. The presence of the free surface would allow the dislocations to annihilate, causing a higher elastic recovery during the unloading of pillar indentation.

scholarly journals Effect of growth conditions on the mechanical properties of lanthanum-gallium tantalate crystals

2020 ◽  
Vol 6 (2) ◽  
pp. 65-70
Author(s):  
Mark V. Weintraub ◽  
Nina S. Kozlova ◽  
Evgeniya V. Zabelina ◽  
Mikhail I. Petrzhik
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Elastic Recovery ◽  
Growth Conditions ◽  
Piezoelectric Response ◽  
Instrumented Indentation ◽  
Recovery Coefficient ◽  
Hardness Tester ◽  
Growth Atmosphere ◽  
Oxygen Addition

The effect of growth conditions, anisotropy and polarity of specimens on the mechanical properties of lanthanum-gallium tantalate La3Ta0.5Ga5.5O14 single crystals grown in different atmospheres (argon (Ar), argon with oxygen addition (Ar+(<2%)O2 and Ar+(2%)O2) and air) was studied. The test specimens for the measurements were cut perpendicularly to a 3rd order axis (Z cuts) and in polar directions perpendicular to a 2nd order axis (Y cuts). The polarity of the Y cut specimens was tested by piezoelectric response. The brittleness was evaluated by microindentation at 3, 5, 10 and 25 g loads. The brittleness proved to show itself at a 5 g and the higher loads regardless of growth atmosphere. Therefore microhardness tests were done at loads of within 3 g. The microhardness HV of the specimens was measured with an DM 8B Affri microhardness tester by Vickers methods. The hardness H, elastic modulus E and elastic recovery coefficient R were measured with a Berkovich pyramid on a CSM Nano-Hardness Tester using the instrumented indentation (nanoindentation) method. Growth atmosphere was shown to affect the mechanical properties of lanthanum-gallium tantalate crystals: crystals grown in an oxygen-free argon atmosphere had the lowest microhardness, hardness, elastic modulus and elastic recovery coefficient. The lowest microhardness was detected in Z cut specimens regardless of growth atmosphere. The mechanical properties of polar Y cuts proved to be anisotropic: the microhardness, hardness, elastic modulus and elastic recovery coefficient of these cuts were lower for positive cuts than for negative ones regardless of growth atmosphere. Y and Z cut langatate specimens grown in argon with less than two percent oxygen exhibited strong elastic modulus and elastic recovery coefficient anisotropy.

The Effect of Solid Solution Impurities on Dislocation Nucleation in a (001) Mo – 1.5 at.% Ir Single Crystal

2010 ◽  
Vol 662 ◽  
pp. 85-93
Author(s):  
Sergey Dub ◽  
Igor Zasimchuk ◽  
Leonid Matvienko
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Shear Stress ◽  
Elastic Modulus ◽  
Single Crystal ◽  
Single Crystals ◽  
Free Volume ◽  
Dislocation Nucleation ◽  
Initial Portion ◽  
G 12

Mechanical properties of (001) Mo and (001) Mo – 1.5 at.% Ir single crystals have been studied by nanoindentation. It has been found that the iridium addition to molybdenum leads to an increase in both hardness and elastic modulus. An abrupt elasto-plastic transition (pop-in) at a depth of about 20 - 40 nm caused by dislocation nucleation in previously dislocation-free volume has been observed in the initial portion of the loading curve. It has shown that the Ir addition essentially affects the dislocation nucleation. Mean shear stress required for the dislocation nucleation increased from 10.8 GPa (G/12) for a Mo single crystal to 18.2 GPa (G/8) for the Mo – 1.5 at% Ir solid solution. Thus, the Ir solution in a Mo single crystal affects not only the resistance to the motion of dislocations (hardness) but the nucleation of them as well. The latter is likely to occur as a result of an increase in the structure perfection of the Mo – 1.5 at% Ir solid solution as compared to the pure Mo single crystal.

scholarly journals Atomistic Simulations of Dislocations in Confined Volumes

MRS Bulletin ◽  
2009 ◽  
Vol 34 (3) ◽  
pp. 184-189 ◽  
Author(s):  
P.M. Derlet ◽  
P. Gumbsch ◽  
R. Hoagland ◽  
J. Li ◽  
D.L. McDowell ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Time Scale ◽  
Finite Temperature ◽  
Atomistic Simulation ◽  
Dislocation Nucleation ◽  
Atomic Scale ◽  
Atomistic Simulations ◽  
Complementary Role ◽  
Nanocrystalline Structures ◽  
Strength And Ductility

AbstractInternal microstructural length scales play a fundamental role in the strength and ductility of a material. Grain boundaries in nanocrystalline structures and heterointerfaces in nanolaminates can restrict dislocation propagation and also act as a source for new dislocations, thereby affecting the detailed dynamics of dislocation-mediated plasticity. Atomistic simulation has played an important and complementary role to experiment in elucidating the nature of the dislocation/interface interaction, demonstrating a diversity of atomic-scale processes covering dislocation nucleation, propagation, absorption, and transmission at interfaces. This article reviews some atomistic simulation work that has made progress in this field and discusses possible strategies in overcoming the inherent time scale challenge of finite temperature molecular dynamics.

scholarly journals FeZrN Films: Magnetic and Mechanical Properties Relative to the Phase-Structural State

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 137
Author(s):  
Elena N. Sheftel ◽  
Valentin A. Tedzhetov ◽  
Eugene V. Harin ◽  
Philipp V. Kiryukhantsev-Korneev ◽  
Galina S. Usmanova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Magnetic Properties ◽  
Elastic Modulus ◽  
Elastic Recovery ◽  
The Other ◽  
Magnetron Deposition ◽  
Glass Substrates ◽  
Saturation Induction ◽  
Low Elastic Modulus ◽  
Chemical And Phase Compositions

The paper presents results of investigation of Fe65.3–100Zr34.7–0N7.5–0 films prepared by dc magnetron deposition on glass substrates and subsequent 1-hour annealing at temperatures of 300–600 °C. The influence of the chemical and phase compositions and structure of the films, which were studied by TEM, SEM, XRD, and GDOES, on their mechanical properties determined by nanoindentation and static magnetic properties measured by VSM method is analyzed. The studied films exhibit the hardness within a range of 14–21 GPa, low elastic modulus (the value can reach 156 Gpa), and an elastic recovery of 55–83%. It was shown that the films are strong ferromagnets with the high saturation induction Bs (up to 2.1 T) and low coercive field Hc (as low as 40 A/m). The correlations between the magnetic and mechanical properties, on one hand, and the chemical composition of the films, their phase, and structural states as well, on the other hand, are discussed.

Estimating Energy Dissipation of Ceramics via H-E Ratio

2010 ◽  
Vol 434-435 ◽  
pp. 205-208
Author(s):  
Yi Wang Bao ◽  
De Tian Wan ◽  
Yan Qiu
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Energy Dissipation ◽  
Elastic Recovery ◽  
Engineering Application ◽  
Basic Data ◽  
Recovery Resistance ◽  
Reduced Modulus ◽  
Energy Dissipation Capacity

Mechanical properties of ceramics are important for its engineering application. It would be significant and efficient if some properties could be estimated without tests. Energy dissipation capacity of ceramics is estimated in this work via two common parameters, hardness and elastic modulus, which could be obtained from basic data of commercial ceramics or simple tests. The ratio of hardness to reduced modulus H/Er is found to be related to recovery resistance and energy dissipation capacity of the materials, and the related equations were induced. The reduced modulus can be expressed by conventional elastic modulus E. Thus, the capacity of energy dissipation and elastic recovery can be estimated simply from the H/E ratio. The calculated results indicate that the value of H/E ratio is in reverse proportion to the energy dissipation. Several ceramics with different H/E ratio are analyzed and their energy dissipation capacities are estimated.

Atomistic simulation for the size effect on the mechanical properties of Ni/Ni3Al nanowire

2013 ◽  
Vol 114 (9) ◽  
pp. 094303 ◽  
Author(s):  
Xiyuan Yang ◽  
Shifang Xiao ◽  
Wangyu Hu
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Atomistic Simulation

scholarly journals Sample size effect on micro-mechanical properties of gold electroplated with dense carbon dioxide

2018 ◽  
Vol 350 ◽  
pp. 1065-1070 ◽  
Author(s):  
Haochun Tang ◽  
Ken Hashigata ◽  
Tso-Fu Mark Chang ◽  
Chun-Yi Chen ◽  
Takashi Nagoshi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Size Effect ◽  
Sample Size ◽  
Dense Carbon Dioxide ◽  
Sample Size Effect

Elastic-Plastic Deformation of KDP Crystals under Nanoindentation

2013 ◽  
Vol 773-774 ◽  
pp. 705-711 ◽  
Author(s):  
Jing Peng ◽  
Liang Chi Zhang ◽  
Xin Chun Lu
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Potassium Dihydrogen Phosphate ◽  
Dislocation Nucleation ◽  
Dihydrogen Phosphate ◽  
Potassium Dihydrogen ◽  
Diamond Indenter ◽  
The Common ◽  
Kdp Crystals ◽  
Yielding Point

This paper investigates the mechanical properties of potassium dihydrogen phosphate (KDP) crystals with the aid of nanoindentation using a conical diamond indenter. It was found that when unloading is after the first pop-in, the common method of obtaining elastic modulus from the unloading curve of nanoindentation is no longer applicable, because the unloading is inelastic. The study revealed that the pop-in could be due to dislocation nucleation and propagation, and that the first pop-in occurs under a stress below that of the major dislocation burst. Hence, the macroscopic yielding point, which is usually regarded as the onset of plasticity of a material, is nanoscopically not a critical point of the first dislocation in KDP. The study found that the elastic modulus of KDP indenting on its (001) plane is 52.8±3.8GPa. The hardness of the material is 1.89±0.05GPa.

scholarly journals Mechanical properties of ultra-high pressure sintered sphene (CaTiSiO5)

2016 ◽  
Vol 10 (4) ◽  
pp. 295-298
Author(s):  
Eranezhuth Awin ◽  
Branko Matovic ◽  
Jelena Maletaskic ◽  
Vladimir Urbanovich ◽  
Ravi Kumar
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Pressure ◽  
Elastic Modulus ◽  
High Pressures ◽  
Elastic Recovery ◽  
Maximum Load ◽  
Indentation Hardness ◽  
Ultra High Pressure ◽  
Indentation Crack

The investigation of nano-mechanical properties of sphene sintered under ultra-high pressures in the order of 4GPa is done using indentation techniques. An indentation hardness of 6.6GPa and reduced elastic modulus of 112.3GPa is reported at maximum load of 7mN. The material exhibits a high elastic recovery (~59.1%) and the nature of deformation mechanism has been comprehended from the plastic work ratio. In addition, the fracture toughness of the material is also evaluated using indentation crack length method.

Developing Coarse-Grained Force Fields of Poly (methylmethacrylate-b-2-vinylpyridine) from Atomistic Simulation

2012 ◽  
Vol 562-564 ◽  
pp. 123-128 ◽  
Author(s):  
Bo Du ◽  
Zi Lu Wang ◽  
Xue Hao He
Keyword(s):  
Mechanical Properties ◽  
Force Field ◽  
Self Assembly ◽  
Atomistic Simulation ◽  
Polymer Melts ◽  
Coarse Grained ◽  
Atomistic Simulations ◽  
Inversion Method ◽  
Coarse Grained Model ◽  
Vinyl Pyridine

A coarse-grained force field for poly (methylmethacrylate-b-2-vinyl pyridine) is developed based on the Iterative Boltzmann Inversion method. The proposed coarse-grained model, successfully reproduced the properties of the polymer melts obtained from atomistic simulations, may provide an efficient way to study their mechanical properties and self-assembly behaviors.

Sign in / Sign up

Export Citation Format

Share Document