Deformation of Porous, Nanostructured Silver at Room Temperature and 150 °C

2013 ◽  
Vol 1513 ◽  
Author(s):  
Guillaume Noiseau ◽  
Michael F. Becker ◽  
John W. Keto ◽  
Desiderio Kovar
Keyword(s):  
Room Temperature ◽  
Local Strain ◽  
Direct Write ◽  
Compression Tests ◽  
Sufficient Energy ◽  
Starting Point ◽  
Mean Size ◽  
Constant Displacement ◽  
Patterned Films ◽  
Porous Silver

ABSTRACTPorous, nanostructured silver samples were produced using a direct-write method where a nanoparticle aerosol consisting of particles with a mean size of approximately 5 nm were accelerated to speeds of approximately 1000 m/sec and impacted onto a translating substrate [1]. The impacting particles have sufficient energy to stick to the substrate, allowing patterned thick films to be directly written from the aerosol without a mask. Unlike other low temperature processing routes for achieving patterned films, no organics are added that can interfere with postdeposition processing. Typical films are 5- 100 μm thick, up to several centimeters long, and have an as-deposited relative densities as high as 70% of bulk Ag. Compression tests were carried out in steps at room temperature and at 150°C under constant displacement rates. Local strain and densification were measured by optical profilometry between each compression step. The results can be used as a starting point to better understand the mechanisms that govern plasticity, creep, and sintering in nanostructured, porous silver at low processing temperatures.

Microstructure Evolution of AZ31 Magnesium Alloy during Warm Compression Forming

2007 ◽  
Vol 539-543 ◽  
pp. 1813-1817
Author(s):  
Zhi Min Zhang ◽  
Qiang Wang ◽  
B.C. Li ◽  
X. Zhang
Keyword(s):  
Microstructural Evolution ◽  
Room Temperature ◽  
Effective Strain ◽  
Mg Alloy ◽  
Compression Tests ◽  
Az31 Mg Alloy ◽  
Microstructural Evaluation ◽  
Mean Size ◽  
The Mean ◽  
Different Thickness

Warm compression tests of AZ31 Mg alloy were carried out at five temperatures in 30°C intervals from 210°C to 330°C. The samples of different thickness which were machined from as-cast and pre-strained AZ31 billets were compressed into thickness 1mm and then cooled in the air to room temperature. The microstructural evolution of AZ31 Mg alloy was investigated during warm compression forming. The results show that all the samples have undergone a microstructure changes to different scales in the range investigated. The twinning is the predominant deformation mechanism for magnesium alloys at moderate temperatures and its occurrence is dependent on temperature and strain. Microstructural evaluation indicates that the mean size of the recrystallised grains decreases with increasing effective strain and temperature because of sufficient dynamic recrystallization. The original grain has significant influence on microstructural evolution during warm forming.

Dynamic Strain Aging in Biomedical Co–Cr–Mo-Based Alloys with Nitrogen Doping

2012 ◽  
Vol 508 ◽  
pp. 141-145 ◽  
Author(s):  
Kenta Yamanaka ◽  
Manami Mori ◽  
Yun Ping Li ◽  
Yuichiro Koizumi ◽  
Akihiko Chiba
Keyword(s):  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Room Temperature ◽  
Electron Backscatter Diffraction ◽  
Flow Behavior ◽  
Local Strain ◽  
Dynamic Strain ◽  
Compression Tests ◽  
Partial Dislocations ◽  
Plastic Deformation Behavior

The Plastic Deformation Behavior of a Biomedical Co–29Cr–6Mo–0.2N (wt.%) Alloy with a Fully γ (fcc) Matrix Was Studied by Compression Tests from Room Temperature to 1073 K. Serrated Stress–Strain Curves Caused by Dynamic Strain Aging (DSA) Was Clearly Observed at Temperatures of 773–973 K at a Strain Rate of 10−4s−1. Such a Flow Behavior Was Not Observed Significantly in other Conditions. Electron Backscatter Diffraction (EBSD) Analysis Revealed that Deformation Microstructures with DSA Occurrence Exhibited a Large Lattice Distortion over the Grains, while Local Strain Preferentially Increased in the Vicinity of Grain Boundaries in the Specimen Deformed at Room Temperature. Dislocations Were Dissociated into Stacking Faults (SFs) Bounded by Shockley Partial Dislocations both before and after Deformation; the DSA Observed in this Alloy Would Originate from the Interactions between Nitrogen Atoms and the Partial Dislocations/SFs.

scholarly journals Room-temperature deformation of single crystals of ZrB2 and TiB2 with the hexagonal AlB2 structure investigated by micropillar compression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhenghao Chen ◽  
Bhaskar Paul ◽  
Sanjib Majumdar ◽  
Norihiko L. Okamoto ◽  
Kyosuke Kishida ◽  
...  
Keyword(s):  
Single Crystals ◽  
Plastic Flow ◽  
Room Temperature ◽  
Resolve Shear Stress ◽  
Temperature Deformation ◽  
Slip Systems ◽  
Compression Tests ◽  
Plastic Deformation Behavior ◽  
Bulk Single Crystals ◽  
Micropillar Compression

AbstractThe plastic deformation behavior of single crystals of two transition-metal diborides, ZrB2 and TiB2 with the AlB2 structure has been investigated at room temperature as a function of crystal orientation and specimen size by micropillar compression tests. Although plastic flow is not observed at all for their bulk single crystals at room temperature, plastic flow is successfully observed at room temperature by the operation of slip on {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 3> in ZrB2 and by the operation of slip on {1$${\bar{1}}$$ 1 ¯ 00}<0001> and {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 0> in TiB2. Critical resolve shear stress values at room temperature are very high, exceeding 1 GPa for all observed slip systems; 3.01 GPa for {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 3> slip in ZrB2 and 1.72 GPa and 5.17 GPa, respectively for {1$${\bar{1}}$$ 1 ¯ 00}<0001> and {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 0> slip in TiB2. The identified operative slip systems and their CRSS values are discussed in comparison with those identified in the corresponding bulk single crystals at high temperatures and those inferred from micro-hardness anisotropy in the early studies.

Compression of Single-Crystal Micropillars of the Γ Intermetallic Phase in the Fe-Zn System

2014 ◽  
Vol 922 ◽  
pp. 264-269 ◽  
Author(s):  
Masahiro Inomoto ◽  
Norihiko L. Okamoto ◽  
Haruyuki Inui
Keyword(s):  
Single Crystal ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Intermetallic Phase ◽  
Gamma Phase ◽  
Compression Tests ◽  
Slip Direction ◽  
Beam Method

The deformation behavior of the Γ (gamma) phase in the Fe-Zn system has been investigated via room-temperature compression tests of single-crystal micropillar specimens fabricated by the focused ion beam method. Trace analysis of slip lines indicates that {110} slip occurs for the specimens investigated in the present study. Although the slip direction has not been uniquely determined, the slip direction might be <111> in consideration of the crystal structure of the Γ phase (bcc).

Lead inclusions in aluminium

1989 ◽  
Vol 157 ◽  
Author(s):  
E. Johnson ◽  
L. Gråbaek ◽  
J. Bohr ◽  
A. Johansen ◽  
L. Sarholt-Kristensen ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Room Temperature ◽  
Noble Gas ◽  
Melting Transition ◽  
X Ray Diffraction ◽  
Free Surfaces ◽  
The Matrix ◽  
Mean Size ◽  
The Mean ◽  
Spontaneous Phase

ABSTRACTIon implantation at room temperature of lead into aluminium leads to spontaneous phase separation and formation of lead precipitates growing topotactically with the matrix. Unlike the highly pressurised (∼ 1–5 GPa) solid inclusions formed after noble gas implantations, the pressure in the lead precipitates is found to be less than 0.12 GPa.Recently we have observed the intriguing result that the lead inclusions in aluminium exhibit both superheating and supercooling [1]. In this paper we review and elaborate on these results. Small implantation-induced lead precipitates embedded in an aluminium matrix were studied by X-ray diffraction. The (111) Bragg peak originating from the lead crystals was followed during several temperature cycles, from room temperature to 678 K. The melting temperature for bulk lead is 601 K. In the first heating cycle we found a superheating of the lead precipitates of 67 K before melting occurred. During subsequent cooling a supercooling of 21 K below the solidification point of bulk lead was observed. In the subsequent heating cycles this hysteresis at the melting transition was reproducible. The full width of the hysteresis loop slowly decreased to 62 K, while the mean size of the inclusions gradually increased from 14.5 nm to 27 nm. The phenomena of superheating and supercooling are thus most pronounced for the small crystallites. The persistence of the hysteresis loop over successive heating cycles demonstrate that its cause is intrinsic in nature, and it is believed that the superheating originates from the lack of free surfaces of the lead inclusions.

scholarly journals Quantitative 3D imaging of partially saturated granular materials under uniaxial compression

2021 ◽  
Author(s):  
Marius Milatz ◽  
Nicole Hüsener ◽  
Edward Andò ◽  
Gioacchino Viggiani ◽  
Jürgen Grabe
Keyword(s):  
Granular Materials ◽  
Uniaxial Compression ◽  
Water Clusters ◽  
Local Strain ◽  
Confining Pressure ◽  
Mechanical Effect ◽  
Compression Tests ◽  
Initial Water ◽  
Interfacial Areas ◽  
Membrane Effects

AbstractGauging the mechanical effect of partial saturation in granular materials is experimentally challenging due to the very low suctions resulting from large pores. To this end, a uniaxial (zero radial stress) compression test may be preferable to a triaxial one where confining pressure and membrane effects may erase the contribution of this small suction; however, volume changes are challenging to measure. This work resolves this limitation by using X-ray imaging during in situ uniaxial compression tests on Hamburg Sand and glass beads at three different initial water contents, allowing a suction-dependent dilation to be brought to the light. The acquired tomography volumes also allow the development of air–water and solid–water interfacial areas, water clusters and local strain fields to be measured at the grain scale. These measurements are used to characterise pertinent micro-scale quantities during shearing and to relate them to the measured macroscopic response. The new and well-controlled data acquired during this experimental campaign are hopefully a useful contribution to the modelling efforts—to this end they are shared with the community.

Dynamic and Quasi-Static Compressive Deformation Behaviour of Polyimide Foam at Various Elevated Temperature

2014 ◽  
Vol 566 ◽  
pp. 158-163 ◽  
Author(s):  
A. Yosimoto ◽  
Hidetoshi Kobayashi ◽  
Keitaro Horikawa ◽  
Keiko Watanabe ◽  
Kinya Ogawa
Keyword(s):  
Compressive Strength ◽  
Room Temperature ◽  
Deformation Behaviour ◽  
Testing Machine ◽  
Negative Temperature ◽  
Strain Rates ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
Universal Testing ◽  
Pressure Bar

In order to clarify the effect of strain rate and test temperature on the compressive strength and energy absorption of polyimide foam, a series of compression tests for the polyimide foam with two different densities were carried out. By using three testing devices, i.e. universal testing machine, dropping weight machine and sprit Hopkinson pressure bar apparatus, we performed a series of compression tests at various strain rates (10-3~103s-1) and at several test temperatures in the range of room temperature to 280 ̊C. At over 100 s-1, the remarkable increase of flow stress was observed. The negative temperature dependence of strength was also observed.

Unraveling the structural transition mechanism of room-temperature compressed graphite carbon

2021 ◽  
Vol 23 (36) ◽  
pp. 20560-20566
Author(s):  
Sheng-cai Zhu ◽  
Qing-yang Hu
Keyword(s):  
High Pressure ◽  
Crystal Orientation ◽  
Room Temperature ◽  
Structural Transition ◽  
Local Strain ◽  
Transition Mechanism

We resolve the transition pathway of compressed graphite, whose complex high-pressure structure is formed by shearing the boat architecture without nuclei core and controlled by local strain and crystal orientation.

Influence of High Temperatures on the Mechanical Properties of Wood Bio-Concretes

2022 ◽  
Author(s):  
Amanda Lorena Dantas Aguiar ◽  
M’hamed Yassin Rajiv da Gloria ◽  
Romildo Dias Toledo Filho
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperatures ◽  
Room Temperature ◽  
Plant Biomass ◽  
Compression Tests ◽  
Wood Degradation ◽  
Cementitious Matrix ◽  
Wood Shavings ◽  
Temperature Reference

The use of wood wastes in the production of bio-concrete shows high potential for the development of sustainable civil construction, since this material, in addition to having low density, increases the energy efficiency of buildings in terms of thermal insulation. However, a concern arising from the production of bio-concretes with high amounts of plant biomass is how this material behaves when subjected to high temperatures. Therefore, this work aims to evaluate the influence of high temperatures on the mechanical properties of wood bio-concretes. The mixtures were produced with wood shavings volumetric fractions of 40, 50 and 60% and cementitious matrix composed of a combination of cement, fly ash and metakaolin. Uniaxial compression tests and scanning electron microscopy (SEM) were performed, with bio-concrete at age of 28 days, at room temperature (reference) and after exposure to temperatures of 100, 150, 200 and 250 °C. The density and compressive strength of the bio-concrete gradually decreased with increasing biomass content. Up to 200 °C, reductions in strength and densities less than 19% and 13%, respectively, were observed. At 250 °C, reductions of compressive strength reached 87%. Analysis performed by SEM showed an increase in the number of cracks in the wood-cementitious matrix interface and wood degradation by increasing the temperature.

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