scholarly journals Revealing the Plastic Mode of Time-Dependent Deformation of a LiTaO3 Single Crystal by Nanoindentation

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 878
Author(s):  
Shengyun Zhou ◽  
Xianwei Huang ◽  
Congda Lu ◽  
Yunfeng Liu ◽  
Taihua Zhang ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Room Temperature ◽  
Time Dependent ◽  
High Shear ◽  
Compression Stress ◽  
Creep Flow ◽  
Secondary Cracks ◽  
Loading Sequence ◽  
Surface Morphologies

Recently, instrumental nanoindentation has been widely applied to detect time-dependent plastic deformation or creep behavior in numerous materials, particularly thin films and heterogeneous materials. However, deformation mechanism at nanoindentation holding stage has not been well revealed hitherto. In the current work, nanoindentation holding tests with high loads were performed on a brittle LiTaO3 single crystal. The surface morphologies of residual impressions with various holding times were investigated. It was indicated that generation of secondary cracks and propagation of both main and secondary cracks were the dominating mechanism for time-dependent plastic deformation at the initial holding stage, and the density and length of cracks were invariable at the steady-state holding stage, which suggested a nonlocalized plastic deformation beneath the indenter. It could be concluded that time-dependent plastic deformation of brittle ceramic under nanoindentation is composed of instant cracking as the continuation of loading sequence and homogeneous creep flow by high shear-compression stress at room temperature.

Plastic deformation mechanisms in a new Ni-base single crystal superalloy at room temperature

2017 ◽  
Vol 268 (2) ◽  
pp. 186-192 ◽  
Author(s):  
P. ZHANG ◽  
Y. YUAN ◽  
Z. GAO ◽  
B. LI ◽  
G. YANG ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Room Temperature ◽  
Single Crystal Superalloy ◽  
Deformation Mechanisms

Preliminary Investigations of a High Temperature Cu-13.3%Al-4%Ni Shape Memory Alloy Single Crystal

2003 ◽  
Author(s):  
Steve Trigwell ◽  
Ganesh Kumara K. ◽  
Abhijit Bhattacharyya ◽  
Muhammed A. Qidwai
Keyword(s):  
Plastic Deformation ◽  
Shape Memory Alloy ◽  
Single Crystal ◽  
Shape Memory ◽  
Room Temperature ◽  
Alloy Single Crystal ◽  
Stress Strain ◽  
Stress Cycling ◽  
Constitutive Response ◽  
Martensite Reorientation

Preliminary investigations on the constitutive response of a Cu-13.3%Al-4%Ni (wt%) shape memory alloy single crystal with stress-free transformation temperatures around 100 to 150°C are reported. Room temperature stress cycling tests were carried out at very low deformation rates. Reproducible stress/strain curves of up to 9% strain due to detwinning (martensitematensite phase transformations) with no plastic deformation were obtained. The data also indicated that a period of stress cycling is required to stabilize the material before reproducible stress-strain curves are obtained due to martensite reorientation.

scholarly journals On the Room-Temperature Creep Behavior and Its Correlation with Length Scale of a Litao3 Single Crystal by Spherical Nanoindentation

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4213
Author(s):  
Wei Hang ◽  
Xianwei Huang ◽  
Min Liu ◽  
Yi Ma
Keyword(s):  
Strain Rate ◽  
Single Crystal ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Room Temperature ◽  
Length Scale ◽  
Compression Stress ◽  
Temperature Creep ◽  
Strain And Strain Rate ◽  
Room Temperature Creep

Relying on nanoindentation technology, the room-temperature creep behavior of a LiTaO3 single crystal in the typical orientation (01 1 ¯ 2), i.e., Y-42° plane was investigated. Three kinds of spherical tips with the radii of 0.76, 2.95 and 9.8 μm were respectively applied to detect nanoindentation length scale effect on creep deformation at both elastic and plastic regions. Superficially, both creep displacement and rate were nearly linearly increased with increasing holding depth and independent of tip size, which could be ascribed to the simultaneously enlarged holding strain and deformation volume beneath the indenter. At a similar holding strain, creep deformation, i.e., creep strain and strain rate were more pronounced under smaller spherical tips. Strain rate sensitivities of creep flows under different spherical tips and holding strains were also estimated. The potential room-temperature creep mechanism of LiTaO3 under high shear compression stress was discussed.

Tribological Properties of KDP Single Crystal

2014 ◽  
Vol 490-491 ◽  
pp. 134-137
Author(s):  
Chun Peng Lu ◽  
Hang Gao ◽  
Xiao Ji Teng
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Tribological Properties ◽  
Room Temperature ◽  
Surface Damage ◽  
Kdp Crystal ◽  
Scratch Tests ◽  
Elastic And Plastic Deformation ◽  
Kdp Crystals

Scratch tests on (001) face, doubler face and tripler face of KDP crystals are carried out at room temperature. It shows that the friction ceoffcients of different crystal faces are affected seriously by the crystal oritations, their variation periods of (001) face, doubler face and tripler face are 90o, 180o and 180o, their attitudes of relative anisotropy are 50%, 43.8% and 43.8%, and all of them are less than 0.4. The scratch mechanism of KDP crystal consists of four types: elastic and plastic deformation, ploughing, microchip, and surface damage. Differences between elastic and plastic deformation and ploughing are not obvious due to the soft-brittle nature of KDP crystal.

Thioether linked meso functionalized BODIPY DYEmer

2021 ◽  
pp. A-H
Author(s):  
Bhausaheb Dhokale ◽  
Indresh Singh Yadav ◽  
Shaikh M. Mobin ◽  
Rajneesh Misra
Keyword(s):  
Dft Calculations ◽  
Single Crystal ◽  
Room Temperature ◽  
Structural Parameters ◽  
Time Dependent ◽  
Lumo Energy ◽  
X Ray ◽  
X Ray Crystallography ◽  
Td Dft ◽  
Meso Position

Thioether linked meso BODIPY DYEmer 3 was synthesized by two different routes. The reaction of dipyrrothioketone 1 and 8-chloro BODIPY 2 in the presence of triethylamine followed by complexation with [Formula: see text] resulted in thioether linked meso functionalized BODIPY DYEmer 3. Using another route, the reaction of 8-chloro BODIPY 2 with sodium hydrosulphide (NaSH) at room temperature resulted in the thioether linked meso BODIPY DYEmer 3. The DYEmer 3 was characterized by 1H, [Formula: see text]C, [Formula: see text]B, [Formula: see text]F NMR, HRMS, and single crystal X-ray crystallography. The properties of DYEmer 3 was compared with the previously reported thioether linked [Formula: see text] and [Formula: see text] BODIPY DYEmers 4 and 5. The structural parameters indicating the intramolecular arrangements of two BODIPY units of DYEmer were compared and corelated with the observed properties. The time-dependent DFT (TD-DFT) calculations suggested that the thioether group at meso position of BODIPY 3 stabilizes the LUMO energy than 8-chloro BODIPY 2. Compared to 8-chloro BODIPY 2 the HOMO-1 of DYEmer 3 is destabilized whereas the LUMO+1 is stabilized.

scholarly journals Room Temperature Ferroelastic Creep Behavior of Porous (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1346
Author(s):  
Barbara Arnauda ◽  
Ali Akbari-Fakhrabadi ◽  
Nina Orlovskaya ◽  
Viviana Meruane ◽  
Wakako Araki
Keyword(s):  
Room Temperature ◽  
Time Dependent ◽  
Compression Stress ◽  
Lateral Stress ◽  
Deformation Curves ◽  
Lateral Contraction ◽  
Negative Creep ◽  
Creep Deformations ◽  
Uniaxial Compressive Stress ◽  
Applied Stresses

The time-dependent deformation of porous (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) under constant uniaxial compressive stress at room temperature has been studied. Both axial and lateral stress–strain deformation curves clearly show the non-linear ferroelastic behavior of LSCF perovskite during compression. The ferroelastic characteristics of deformation curves such as coercive stress and apparent loading moduli decrease when the porosity of the samples increases. Ferroelastic creep deformations at applied stresses of 25 and 50 MPa demonstrate that stress and porosity are influencing factors on creep deformation, which increases with increasing stress and porosity. A negative creep or axial expansion and lateral contraction were observed in the sample with 35% porosity under 50-MPa constant compression stress.

Time-Dependent Deformation in Room-Temperature Indentation Experiments using a Nanoindenter

1991 ◽  
Vol 239 ◽  
Author(s):  
Shefford P. Baker ◽  
Troy W. Barbee ◽  
William D. Nix
Keyword(s):  
Thin Films ◽  
Plastic Deformation ◽  
Strain Rate ◽  
Room Temperature ◽  
Rate Dependence ◽  
Time Dependent ◽  
Depth Sensing

ABSTRACTTime-dependent deformation in room-temperature indentation is a well known phenomenon which is frequently overlooked in depth-sensing indentation experiments. In this study, the time-dependent displacements which occur during depth-sensing indentation experiments using a Nanoindenter were investigated. Time-dependent displacements were found to result both from plastic deformation of the sample and experimental drift. A simple correction for experimental drift was applied in experiments on sputtered copper thin films and reasonable strain rate sensitivities were obtained. The sources of experimental drift were identified and measured. It appears to be possible to measure the rate-dependence of plastic deformation in a variety of materials using this instrument.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

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