Surface Stress Effects on the Yield Strength in Nanotwinned Polycrystal Face-Centered-Cubic Metallic Nanowires

2014 ◽  
Vol 81 (10) ◽  
Author(s):  
Linli Zhu ◽  
Xiang Guo ◽  
Jian Lu
Keyword(s):  
Yield Strength ◽  
Surface Stress ◽  
Mechanical Performance ◽  
Face Centered Cubic ◽  
Stress Effects ◽  
Size Dependent ◽  
The Wire ◽  
Face Centered ◽  
20 Nm ◽  
Twin Spacing

The influence of surface stress on the yield strength of nanotwinned polycrystal face-centered-cubic (FCC) metallic nanowire is theoretically investigated. The contribution of surface boundaries on the strengthening/softening is analyzed in the framework of continuum mechanics theory by accounting for the surface energy effects. The other strengthening mechanisms originated from the inner boundaries are described by the Taylor model for the nanotwinned polycrystalline metals. The theoretical results demonstrate that the yield strength of nanotwinned polycrystal wires is dependent on the twin spacing, grain size and the geometrical size of the wire. The surface stress effects on the strength perform more and more significantly with decreasing the wire diameter, especially for the diameter smaller than 20 nm. In addition, the dependence of surface stress on the strength is also relevant to the size of microstructures as well as the magnitude and direction of surface stress. These results may be useful in evaluating the size-dependent mechanical performance of nanostructured materials.

scholarly journals Effects of Current on Arc Fabrication of Cu Nanoparticles

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
M. Z. Kassaee ◽  
F. Buazar ◽  
E. Motamedi
Keyword(s):  
Thermal Stability ◽  
Distilled Water ◽  
Face Centered Cubic ◽  
Cu Nanoparticles ◽  
Dta Analysis ◽  
Face Centered ◽  
Average Size ◽  
20 Nm ◽  
Thermal Stability Of ◽  
Sem Analyses

Arc-fabricated copper nanoparticles (Cu Nps) size, morphology and the crystalline structure, as well as the yields of Nps appear sensitive to the applied currents (50–160 A) in distilled water. The results indicate that the sizes of Cu Nps are directly proportional to the currents employed. At 50 A, TEM, XRD, and SEM analyses show fabrication of relatively purest, the most dispersed, face-centered cubic (fcc) brown Cu Nps with rather smallest average size of 20 nm. At the same current, the TGA-DTA analysis reveals neither weight loss nor gain, indicating thermal stability of the fabricated Cu Nps.

scholarly journals Calculation of Surface Properties of Cubic and Hexagonal Crystals through Molecular Statics Simulations

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 329 ◽  
Author(s):  
Zihan Tang ◽  
Yue Chen ◽  
Wei Ye
Keyword(s):  
Surface Properties ◽  
Surface Stress ◽  
Critical Role ◽  
Constitutive Law ◽  
Face Centered Cubic ◽  
Hexagonal Close Packed ◽  
Surface Stiffness ◽  
Pure Metals ◽  
Face Centered ◽  
Hexagonal Crystals

Surface property is an important factor that is widely considered in crystal growth and design. It is also found to play a critical role in changing the constitutive law seen in the classical elasticity theory for nanomaterials. Through molecular static simulations, this work presents the calculation of surface properties (surface energy density, surface stress and surface stiffness) of some typical cubic and hexagonal crystals: face-centered-cubic (FCC) pure metals (Cu, Ni, Pd and Ag), body-centered-cubic (BCC) pure metals (Mo and W), diamond Si, zincblende GaAs and GaN, hexagonal-close-packed (HCP) pure metals (Mg, Zr and Ti), and wurzite GaN. Sound agreements of the bulk and surface properties between this work and the literature are found. New results are first reported for the surface stiffness of BCC pure metals, surface stress and surface stiffness of HCP pure metals, Si, GaAs and GaN. Comparative studies of the surface properties are carried out to uncover trends in their behaviors. The results in this work could be helpful to the investigation of material properties and structure performances of crystals.

Microstructure and Mechanical Behavior of Severely Deformed F.C.C. Metals

2007 ◽  
Vol 567-568 ◽  
pp. 181-184 ◽  
Author(s):  
Jenő Gubicza ◽  
Sergey V. Dobatkin ◽  
Z. Bakai ◽  
Nguyen Q. Chinh ◽  
Terence G. Langdon
Keyword(s):  
Dislocation Density ◽  
Yield Strength ◽  
Shear Modulus ◽  
Mechanical Behavior ◽  
Boundary Structure ◽  
Face Centered Cubic ◽  
Angular Pressing ◽  
Maximum Value ◽  
Grain Boundary Structure ◽  
Face Centered

The correlation between the microstructure and the mechanical behavior of ultrafinegrained face centered cubic (f.c.c.) metals processed by equal-channel angular pressing (ECAP) was studied. It was found that the maximum value of the yield strength obtained at high strains is determined by the shear modulus and the saturation value of the dislocation density according to the Taylor equation. It was also revealed that the value of the parameter α in this equation decreases with decreasing stacking fault energy, indicating the effect of different geometrical arrangements of dislocations in the grain boundaries. In addition, it was shown that for ECAP processed Cu, the ductility decreases with increasing strain but at extremely high strains the ductility is partially restored due to a recovery of the grain boundary structure.

Ozone-Based Atomic Layer Deposition of HfO2 and HfxSi1-xO2 and Film Characterization

2004 ◽  
Vol 811 ◽  
Author(s):  
Yoshihide Senzaki ◽  
Seung Park ◽  
Douglas Tweet ◽  
John F. Conley ◽  
Yoshi Ono
Keyword(s):  
Atomic Layer ◽  
Optical Measurements ◽  
Face Centered Cubic ◽  
Hafnium Silicate ◽  
X Ray ◽  
Layer Deposition ◽  
Face Centered ◽  
Fcc Phase ◽  
20 Nm ◽  
Fcc Structure

Abstract:New ALD processes for hafnium silicate films have been developed at Aviza Technology by co-injection of tetrakis(ethylmethylamino)hafnium and tetrakis(ethylmethylamino)silicon precursors. Alternating pulses of the Hf/Si precursor vapor mixture and ozone allow process temperatures below 400°C to grow HfxSi1-xO2 films. Film characterization, including film density, crystallinity, and thermal anneal effect, was performed on five 20 nm thick HfxSi1-xO2 films where x = 0.2, 0.4, 0.6, 0.8, 1.0. X-ray measurements revealed the film densities and thicknesses for the as-deposited and 1000°C annealed samples. The densification with anneals seen in the optical measurements were confirmed. The as-deposited amorphous HfO2 and Hf0.8Si0.2O2 were crystallized after a 600°C anneal. The HfO2 formed the well known monoclinic phase while the silicate formed a face-centered-cubic (fcc) structure. This fcc phase has only recently been mentioned in the literature [1].

Surface Stress Effect on the Pull-In Instability of Hydrostatically and Electrostatically Actuated Rectangular Nanoplates With Various Edge Supports

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
R. Ansari ◽  
R. Gholami ◽  
M. Faghih Shojaei ◽  
V. Mohammadi ◽  
M. A. Darabi
Keyword(s):  
Boundary Conditions ◽  
Governing Equation ◽  
Surface Stress ◽  
Plate Thickness ◽  
Stress Effect ◽  
Residual Surface Stress ◽  
Electrostatically Actuated ◽  
Stress Effects ◽  
Size Dependent ◽  
Surface Stress Effect

This paper is aimed to investigate the size-dependent pull-in behavior of hydrostatically and electrostatically actuated rectangular nanoplates including surface stress effects based on a modified continuum model. To this end, based on the Gurtin–Murdoch theory and Hamilton's principle, the governing equation and corresponding boundary conditions of an actuated nanoplate are derived; the step-by-step linearization scheme and the differential quadrature (GDQ) method are used to discretize the governing equation and associated boundary conditions. The effects of the thickness of the nanoplate, surface elastic modulus and residual surface stress on the pull-in instability of the nanoplate are investigated. Plates made of two different materials including aluminum (Al) and silicon (Si) are selected to explain the variation of the pull-in voltage and pressure with respect to plate thickness.

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