X-ray line-broadening study of the dislocation cell structure in deformed [001]-orientated copper single crystals

1984 ◽  
Vol 32 (3) ◽  
pp. 333-342 ◽  
Author(s):  
T. Ungar ◽  
H. Mughrabi ◽  
D. Rönnpagel ◽  
M. Wilkens
Keyword(s):  
Single Crystals ◽  
Cell Structure ◽  
Dislocation Cell ◽  
Line Broadening ◽  
X Ray ◽  
Dislocation Cell Structure ◽  
Copper Single Crystals

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.

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.

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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