The Dissociation of Sessile Superdislocations at a Coherent Twin Eoundary in Ordered CU3AU During Plastic Deformation

1990 ◽  
Vol 186 ◽  
Author(s):  
F.D. Tichelaar ◽  
F.W. Schapink
Keyword(s):  
Plastic Deformation ◽  
Shear Stress ◽  
Electron Microscope ◽  
Slip System ◽  
Tensile Axis ◽  
Slip Systems ◽  
Coherent Twin Boundary ◽  
Cube Plane ◽  
Transmission Electron ◽  
The Matrix

AbstractThe glide behaviour of superdislocations at a coherent twin boundary in ordered Cu3Au was examined in a transmission electron microscope for the case when the superdislocations are sessile in the boundary. Possible schemes for dissociation of a superdislocation in the boundary were analysed geometrically. The leading superpartial of each superdislocation dissociated into a superpartial in the matrix and a residual Shockley partial in the boundary of glissile type. The trailing superpartial remained undissociated in the boundary. The superpartial in the matrix glided on a cube plane, and a ribbon of APB connected to the boundary was left in its trail. The cube slip occurs as a result of (i) a maximal resolved shear stress for the observed slip system and (ii) the geometric criteria for slip applied to all possible slip systems in the matrix. The Schmid factors for the slip systems in the matrix could be calculated by assuming a uniform tensile axis in the foil. The tensile axis was deduced from the observed slip systems in the twin.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

Transmission Electron Microscope Specimen Preparation of Metal Matrix Composites Using the Focused Ion Beam Miller

2000 ◽  
Vol 6 (5) ◽  
pp. 452-462 ◽  
Author(s):  
Julie M. Cairney ◽  
Robert D. Smith ◽  
Paul R. Munroe
Keyword(s):  
Electron Microscope ◽  
Metal Matrix Composites ◽  
Transmission Electron Microscope ◽  
Metal Matrix ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Matrix Composites ◽  
Transmission Electron ◽  
The Matrix ◽  
Ceramic Reinforcement

AbstractTransmission electron microscope samples of two types of metal matrix composites were prepared using both traditional thinning methods and the more novel focused ion beam miller. Electropolishing methods were able to produce, very rapidly, thin foils where the matrix was electron transparent, but the ceramic reinforcement particles remained unthinned. Thus, it was not possible in these foils to study either the matrix-reinforcement interface or the microstructure of the reinforcement particles themselves. In contrast, both phases in the composites prepared using the focused ion beam miller thinned uniformly. The interfaces in these materials were clearly visible and the ceramic reinforcement was electron transparent. However, microstructural artifacts associated with ion beam damage were also observed. The extent of these artifacts and methods of minimizing their effect were dependent on both the materials and the milling conditions used.

Characteristic Structure of Cu-0.8Cr Alloy Using SPD Deformation by Rolling with Cyclic Movement of Rolls Method

2016 ◽  
Vol 682 ◽  
pp. 3-9 ◽  
Author(s):  
Anna Urbańczyk-Gucwa ◽  
Kinga Rodak ◽  
Adam Płachta ◽  
Joanna Sobota ◽  
Zbigniew Rdzawski
Keyword(s):  
Plastic Deformation ◽  
Electron Microscope ◽  
Severe Plastic Deformation ◽  
Scanning Transmission Electron Microscope ◽  
Characteristic Structure ◽  
Quantitative Studies ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Cyclic Movement ◽  
Deformation By Rolling

The results of the microstructure and hardness investigations of the Cu-0.8Cr alloy after application of severe plastic deformation (SPD) implemented by rolling with the cyclic movement of rolls (RCMR) are presented in this paper. Performed substructure investigations showed that using the RCMR method can refine the microstructure of Cu-0.8Cr alloy to the ultrafine scale. The structure of the Cu-0.8Cr alloy was analyzed using light microscope (LM) and scanning transmission electron microscope (STEM). The quantitative studies of the substructure was performed with "MET-ILO" software, on the basis of images acquired on STEM microscope.

scholarly journals Study of the Mechanical Properties of a Nanostructured Surface Layer on 316L Stainless Steel

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
F. C. Lang ◽  
Y. M. Xing ◽  
J. Zhu ◽  
Y. R. Zhao
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Surface Layer ◽  
Electron Microscope ◽  
316L Stainless Steel ◽  
Nanostructured Surface ◽  
Transmission Electron ◽  
Tensile Process ◽  
The Matrix ◽  
Reverse Analysis

A nanostructured surface layer (NSSL) was generated on a 316L stainless steel plate through surface nanocrystallization (SNC). The grains of the surface layer were refined to nanoscale after SNC treatment. Moreover, the microstructure and mechanical properties of NSSL were analyzed with a transmission electron microscope (TEM) and scanning electron microscope (SEM), through nanoindentation, and through reverse analysis of finite element method (FEM). TEM results showed that the grains in the NSSL measured 8 nm. In addition, these nanocrystalline grains took the form of random crystallographic orientation and were roughly equiaxed in shape. In situ SEM observations of the tensile process confirmed that the motions of the dislocations were determined from within the material and that the motions were blocked by the NSSL, thus improving overall yielding stress. Meanwhile, the nanohardness and the elastic modulus of the NSSL, as well as those of the matrix, were obtained with nanoindentation technology. The reverse analysis of FEM was conducted with MARC software, and the process of nanoindentation on the NSSL and the matrix was simulated. The plastic mechanical properties of NSSL can be derived from the simulation by comparing the results of the simulation and of actual nanoindentation.

Precipitate Structure in an Alumina Dispersion-Strengthened Copper Base Composite Layer

2010 ◽  
Vol 152-153 ◽  
pp. 634-638
Author(s):  
Bao Hong Tian ◽  
Xiao Hong Chen ◽  
Yi Zhang ◽  
Yong Liu
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Composite Layer ◽  
Lattice Parameter ◽  
Interface Structure ◽  
Parameter Mismatch ◽  
Direction Parallel ◽  
Transmission Electron ◽  
The Matrix ◽  
Α Al2o3

A dilute copper alloy of Cu-0.45wt%Al -0.066wt %Y was selected to fabricate nanometer size Al2O3 particles dispersion-hardened composite layer by using aluminizing-internal oxidation technique. The structure and size of the precipitate, interface structure, lattice parameter mismatch and morphology were investigated by means of high resolution transmission electron microscope, analytical transmission electron microscope and image processing by VEC software. Results show that two different size and structure nano-alumina precipitate were identified as α-Al2O3 and γ-Al2O3 respectively during different processing. The precipitates possess semi-coherence or coherence interface structure to matrix with typical loop-loop contrast. The cubic γ-Al2O3 precipitate in certain crystal plane and direction parallel to the matrix。

scholarly journals Rheological Behavior of Carbon Nanotubes as an Additive on Lithium Grease

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Alaa Mohamed ◽  
Aly Ahmed Khattab ◽  
Tarek Abdel Sadek Osman ◽  
Mostafa Zaki
Keyword(s):  
Carbon Nanotubes ◽  
Shear Stress ◽  
Electron Microscope ◽  
Apparent Viscosity ◽  
Experimental Investigations ◽  
Lithium Grease ◽  
Transmission Electron ◽  
Viscosity Increase ◽  
Homogeneous Network ◽  
Long Fibers

The rheological behaviors of carbon nanotubes (CNTs) as an additive on lithium grease at different concentrations were examined under various settings of shear rate, shear stress, and apparent viscosity. The results indicated that the optimum content of the CNTs was 2%. These experimental investigations were evaluated with a Brookfield Programmable Rheometer DV-III ULTRA. The results indicated that the shear, stress and apparent viscosity increase with the increase of CNTs concentration. The microstructure of CNTs and lithium grease was examined by high resolution transmission electron microscope (HRTEM) and scanning electron microscope (SEM). The results indicated that the microscopic structure of the lithium grease presents a more regular and homogeneous network structure, with long fibers, which confirms the rheological stability.

The Slip Transfer Process Through Grain Boundaries in HCP Ti

1993 ◽  
Vol 319 ◽  
Author(s):  
J. Shirokoff ◽  
I.M. Robertson ◽  
H.K. Birnbaum
Keyword(s):  
Grain Boundary ◽  
Slip System ◽  
Grain Boundaries ◽  
Slip Systems ◽  
Boundary Dislocation ◽  
Burgers Vector ◽  
Slip Transfer ◽  
Transmission Electron ◽  
Fcc Materials

AbstractInformation on the mechanisms of slip transfer across grain boundaries in an HCP α-Ti alloy has been obtained from deformation experiments performed In situ in the transmission electron microscope. Initially, lattice dislocations are accommodated within the grain boundary until a critical local dislocation density is reached. The boundary then responds by activating slip in the adjoining grain on the slip system experiencing the highest local resolved shear stress and producing the residual grain-boundary dislocation with the smallest Burgers vector. Slip on secondary slip systems may be initiated provided they reduce the magnitude of the Burgers vector of, or eliminate, the residual grainboundary dislocation. The selection rules used to predict the slip system activated by the grain boundary are the same as apply in ordered and disordered FCC materials.

Mechanical behavior assessment of sucrose using nanoindentation

2007 ◽  
Vol 22 (7) ◽  
pp. 2037-2045 ◽  
Author(s):  
K.J. Ramos ◽  
D.F. Bahr
Keyword(s):  
Experimental Study ◽  
Plastic Deformation ◽  
Shear Stress ◽  
Elastic Modulus ◽  
Slip System ◽  
Single Crystals ◽  
Maximum Shear Stress ◽  
Model Material ◽  
Instrumented Indentation ◽  
Plastic Properties

An experimental study of the elastic and plastic properties of sucrose single crystals, which can be considered to be a model material for both pharmaceutical excipients and explosives, has been carried out using nanoindentation. Instrumented indentation was used to characterize the properties of both habit and cleavage planes on the (100) and (001) orientations; the elastic modulus on the (100) is 38 GPa, while the modulus on the (001) is 33 GPa. The hardness of sucrose is approximately 1.5 GPa. Nanoindentation enables assessment of the onset of plastic deformation on cleaved surfaces, and a maximum shear stress of 1 GPa can be supported prior to plastic deformation. The deformation in this material is crystallographically dependent, with pileup around residual indentation impressions showing evidence of preferential slip system activity.

MICROSTRUCTURE AND FRACTURE TOUGHNESS OF FeNiCr-TiC COMPOSITE PRODUCED BY THERMITE REACTION

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2904-2909
Author(s):  
WENJUN XI ◽  
CHAOLIANG SHI
Keyword(s):  
Fracture Toughness ◽  
Electron Microscope ◽  
Aging Temperature ◽  
Aging Treatment ◽  
Ferrite Matrix ◽  
Β Phase ◽  
Transmission Electron ◽  
The Matrix ◽  
Average Size ◽  
Effects Of Aging

The microstructures of the FeNiCr - TiC composite produced by the rapid solidification thermite process were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The effects of aging treatment on the microstructure and fracture toughness of the composite were examined. Results showed that the FeNiCr - TiC composite was composed of ferrite (α- FeNiCr ), TiC and NiAl (β phase). TiC particles in the matrix were in the shape of polygon and uniformly distributed, and their size was less than 3 µm. The β phase was coherent with the ferrite matrix, and its average size was about 50 nm. The fracture toughness of composite was 22 MPa·m1/2 without aging. When the aging temperature was below 600°C, the fracture toughness of the composite had higher plateau values and reached the maximum of 32 MPa·m1/2 at aging temperature 500°C due to the precipitation of NiAl phase on the nanometer scale. The fracture toughness decreased rapidly aged at 650°C, and then kept homology value in the range of 700 to 900°C, which was attributed to the precipitation of needle-shaped carbide ( Cr / Fe )7 C 3 at the grain boundaries.

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