X-ray determination of dislocation density and arrangement in plastically deformed copper

2000 ◽  
Vol 33 (5) ◽  
pp. 1284-1294 ◽  
Author(s):  
D. Breuer ◽  
P. Klimanek ◽  
W. Pantleon
Keyword(s):  
Dislocation Density ◽  
Profile Analysis ◽  
Cell Structure ◽  
Dislocation Cell ◽  
Double Crystal ◽  
Mean Values ◽  
X Ray ◽  
Dislocation Cell Structure ◽  
X Ray Scattering

Using the kinematical theory of X-ray scattering by crystals with dislocations as developed by Krivoglazet al.and Wilkens, the dislocation content of compressed copper single and polycrystals was investigated by means of profile analysis of selected diffraction peaks. Measurements of radial intensity distributionsI(2θ) were performed with a double-crystal spectrometer in the case of the single crystals and with conventional polycrystal diffractometers in the case of the polycrystals. Additionally, the misorientations Θ occurring within the dislocation cell structure because of the accumulation of excess dislocations of one sign were investigated by means of rocking curves of the single-crystal reflections and by evaluation of electron backscattering patterns (EBSPs). Within a wide deformation range, the mean total dislocation density ρdcan be related well to the flow stressviathe Taylor relationship. Assuming a random distribution of the misorientations Θ between adjacent dislocation cells, the evaluation of the rocking curves gives mean values 〈|Θ|〉 much smaller than those determined by EBSP analysis. For this reason, a model of a dislocation cell structure with restrictedly correlated misorientations, which leads to better agreement of the X-ray and the EBSP data, is proposed.

Asymmetric X-ray line broadening of plastically deformed crystals. II. Evaluation procedure and application to [001]-Cu crystals

1989 ◽  
Vol 22 (1) ◽  
pp. 26-34 ◽  
Author(s):  
T. Ungár ◽  
I. Groma ◽  
M. Wilkens
Keyword(s):  
Dislocation Density ◽  
Dislocation Structure ◽  
Cell Structure ◽  
Dislocation Cell ◽  
Line Profiles ◽  
Line Broadening ◽  
Spatial Fluctuation ◽  
X Ray ◽  
Dislocation Cell Structure ◽  
Dipole Polarization

In paper I [Groma, Ungár & Wilkens (1988). J. Appl. Cryst. 21, 47–53] a theory was developed to interpret the asymmetric X-ray line broadening of plastically deformed crystals. It was shown that the dislocation structure can be described by five distinct parameters, namely the dislocation density, the mean quadratic spatial fluctuation of the dislocation density, the effective outer cut-off radius, the dipole polarization and the spatial fluctuation of the dipole polarization of the dislocation structure. In this paper a procedure is developed to evaluate these parameters from the Fourier transform of the line profiles. The theory and this procedure are tested by applying it to the asymmetric line profiles of tensile-deformed Cu single crystals orientated for ideal multiple slip. The asymmetry of these profiles is assigned to the dipole polarization of the dislocation cell structure and is directly correlated to residual long-range internal stresses. It is shown that the data can be interpreted in terms of the quasi-composite model of the dislocation cell structure developed earlier for the same material.

Characterization of aging behavior of precipitates and dislocations in copper-based alloys

2010 ◽  
Vol 25 (2) ◽  
pp. 104-107
Author(s):  
Shigeo Sato ◽  
Yohei Takahashi ◽  
Kazuaki Wagatsuma ◽  
Shigeru Suzuki
Keyword(s):  
Dislocation Density ◽  
Aging Time ◽  
Line Profile ◽  
Small Angle ◽  
Profile Analysis ◽  
Aging Treatment ◽  
Scattering Method ◽  
Line Profile Analysis ◽  
X Ray ◽  
X Ray Scattering

The growth of precipitates in a deformed Cu–Ni–Si alloy with an aging treatment and the rearrangement of dislocations were investigated using small-angle X-ray scattering method and XRD line-profile analysis. The small-angle X-ray scattering method was used for characterizing the growth behavior of the precipitates. The results showed that the precipitates grew gradually to a few nanometers in radius when aged under the condition that the alloy exhibited a maximum of the hardness due to precipitation hardening. The growth rate rose from the onset of the overaging, where the hardness started to decrease. The line-profile analysis of copper-based alloy diffraction peaks using modified Williamson–Hall and modified Warren–Averbach procedures yielded a variation in the dislocation densities of the alloy as a function of the aging time. The dislocation density of the alloy before the aging treatment was estimated to be 1.7×1015 m−2 and its high value was held up to the peak-aging time. With the onset of the overaging, however, the dislocation density distinctly decreased by about 1 order of magnitude indicating that a large amount of the dislocations rearranged to release the alloy from the high dislocation-density state. The results suggest that the massive rearrangement of dislocations was accompanied with coarsening of the precipitates.

Processing of Ultrafine Grained Cu-30%Zn Alloy through Severe Plastic Deformation Using Accumulative Roll Bonding

2010 ◽  
Vol 667-669 ◽  
pp. 571-576
Author(s):  
Sayed Ghafar Hashemi ◽  
Beitallah Eghbali
Keyword(s):  
Dislocation Density ◽  
Size Distribution ◽  
Profile Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ultrafine Grained ◽  
Average Contrast ◽  
Log Normal ◽  
Zn Alloy

In the present research, the microstructural features of ultrafine grained Cu-30 Zn alloy via ARB at room temperature were investigated by X-ray diffraction peak profile analysis. The character of dislocations was determined by analyzing the dislocation contrast factors. The average contrast factors for the different reflections obtained by determination of the type of dislocations and Burgers vectors in crystals. Also, using the modified Williamson–Hall and Warren–Averbach procedure size parameters, the effective outer cut-off radius and density of dislocations were determined. Assuming that the grain size distribution is log-normal, the median and the variance of the size distribution of sub grains were obtained. It was found that the crystallite size is reduced substantially, while the dislocation density increases up to 2 cycles of ARB. After 2nd cycle, dislocation density decreases. This is attributed to the occurrence of dynamic restoration process which takes place during next ARB cycles.

Structure Determination of B4C and SiC Thin Films Via Synchrotron High-Resolution Diffraction

1997 ◽  
Vol 505 ◽  
Author(s):  
J. Hershberger ◽  
F. Kustas ◽  
Z. U. Rek ◽  
S. M. Yalisove ◽  
J. C. Bilello
Keyword(s):  
Thin Films ◽  
Average Density ◽  
Distribution Functions ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Si Substrates ◽  
X Ray Scattering

ABSTRACTThin films of B4C and SiC deposited by magnetron sputtering as components of multilayers have the potential to provide significant property improvements over current wear resistant coating technology. B4C and SiC have previously been found to be amorphous and possibly nanocrystalline under the deposition conditions used. This study reports results of synchrotron x-ray scattering experiments providing information on the degree of crystallinity, strain, average density, and coordination number in 2000 Å films of these compounds on Si substrates. Radial distribution functions from B4C and SiC thin films were obtained and used to model the structure. Strain results are compared with Double Crystal x-ray Diffraction Topography (DCDT) results as a means for establishing a standard strain state.

Systematical Characterization of Material Response to Microscale Laser Shock Peening

2004 ◽  
Vol 126 (4) ◽  
pp. 740-749 ◽  
Author(s):  
Hongqiang Chen ◽  
Youneng Wang ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao
Keyword(s):  
Fourier Analysis ◽  
Cell Structure ◽  
Dislocation Cell ◽  
Laser Shock Peening ◽  
Lattice Rotation ◽  
Strength Increase ◽  
Laser Shock ◽  
X Ray ◽  
Dislocation Cell Structure ◽  
Shock Peening

The response of materials after microscale laser shock peening (μLSP) was experimentally characterized and compared with the theoretical prediction from FEM analysis in microlength level. Since μLSP is predominantly a mechanical process instead of a thermal process, the characterization focuses on mechanical properties and associated microstructures. An X-ray microdiffraction technique was applied on the postpeened single crystal aluminum of (001) and (110) orientations, and an X-ray profile was analyzed by subprofiling and Fourier analysis method. Spatially resolved residual stress and strain deviation was quantified and explained in terms of the heterogeneous dislocation cell structure. In-plane crystal lattice rotation induced by μLSP were measured by electron backscatter diffraction (EBSD) and compared with the FEM simulation. Average mosaic size was evaluated from X-ray profile Fourier analysis and compared with the result from EBSD. Surface strength increase and dislocation cell structure formation were studied. The systematical characterization helps develop more realistic simulation models and obtain better understanding in microlength level.

TEM study on fine carbide precipitates and dislocation cell structure

1990 ◽  
Vol 48 (4) ◽  
pp. 904-905
Author(s):  
Mengzhe Chen ◽  
Siqin Wang ◽  
Jun Ke
Keyword(s):  
Carbide Particle ◽  
Cell Structure ◽  
Ferrite Matrix ◽  
Dislocation Cell ◽  
Isothermal Treatment ◽  
Particle Sizes ◽  
Dislocation Cell Structure ◽  
Thin Foils ◽  
Hsla Steels ◽  
Fine Carbide

A series of investigations have been conducted into the nature and origin of the dislocation cell structure. R.J.Klassen calculated that the dislocation cell limiting size in pure ferrite matrix is about 0.4 μm. M.N.Bassion estimated the size of dislocation cell in deformed ferrite of HSLA steels to be of the same order.In this paper, TEM observation has been concentrated on the interaction of fine carbide precipitates with dislocation cell structure in deformed Fe-C-V (0.05%C, 0.13% and 0.57%V) and Fe-C-Nb (0.07 %C and 0.04%Nb) alloys and compared with that in Fe-C (0.05%). Specimens were austenitized at 1500 “C/20 min and followed by isothermal treatment at 750 °C and 800 “C for 20, 40 and 120 minutes . The carbide particle sizes in these steels are from 9 to 86nm measured from carbon extraction replicas. Specimens for TEM were cut from differently deformed areas of tensile specimens deformed at room temperture. The thin foils were jet electropolished at -20 C in a solution of 10% perchloric acid and 90% ethanol. The TEM observation was carried out in JEM 100CX , EM420 at 100kv and JEM 2000FX at 200kv.

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