Crystallite-Size Distribution and Dislocation Structure in Nanocrystalline HfNi5 Determined by X-Ray Diffraction Profile Analysis

2001 ◽  
Vol 1 (3) ◽  
pp. 343-348 ◽  
Author(s):  
J. Gubicza ◽  
G. Ribárik ◽  
I. Bakonyi ◽  
T. Ungár
2001 ◽  
Vol 34 (3) ◽  
pp. 298-310 ◽  
Author(s):  
T. Ungár ◽  
J. Gubicza ◽  
G. Ribárik ◽  
A. Borbély

Two different methods of diffraction profile analysis are presented. In the first, the breadths and the first few Fourier coefficients of diffraction profiles are analysed by modified Williamson–Hall and Warren–Averbach procedures. A simple and pragmatic method is suggested to determine the crystallite size distribution in the presence of strain. In the second, the Fourier coefficients of the measured physical profiles are fitted by Fourier coefficients of well establishedab initiofunctions of size and strain profiles. In both procedures, strain anisotropy is rationalized by the dislocation model of the mean square strain. The procedures are applied and tested on a nanocrystalline powder of silicon nitride and a severely plastically deformed bulk copper specimen. The X-ray crystallite size distributions are compared with size distributions obtained from transmission electron microscopy (TEM) micrographs. There is good agreement between X-ray and TEM data for nanocrystalline loose powders. In bulk materials, a deeper insight into the microstructure is needed to correlate the X-ray and TEM results.


2003 ◽  
Vol 94 (11) ◽  
pp. 1185-1188 ◽  
Author(s):  
J. Gubicza ◽  
I. C. Dragomir ◽  
G. Ribárik ◽  
S. C. Baik ◽  
Y. T. Zhu ◽  
...  

2008 ◽  
Vol 39 (8) ◽  
pp. 1978-1984 ◽  
Author(s):  
S. Mahadevan ◽  
T. Jayakumar ◽  
B.P.C. Rao ◽  
Anish Kumar ◽  
K.V. Rajkumar ◽  
...  

2000 ◽  
Vol 661 ◽  
Author(s):  
T. Ungár ◽  
J. Gubicza ◽  
G. Ribárik ◽  
T. W. Zerda

ABSTRACTThe crystallite size and size-distribution in carbon blacks in the presence of strain are determined by recently developed procedure of X-ray diffraction peak profile analysis. The Fourier coefficients of the measured physical profiles are fitted by Fourier coefficients of well established ab initio functions of size and strain peak profiles. Strain anisotropy is accounted for by expressing the mean square strain in terms of average dislocation contrast factors. Crystallite shape anisotropy is modelled by ellipsoids incorporated into the size profile function. To make the fitting procedure faster, the Fourier transform of the size profile is given as an analitical function. The method is applied to carbon blacks treated at different preassures and temperatures. The microstructure is characterised in terms of crystallite size distribution, dislocation density, and crystallite shape anisotropy.


2005 ◽  
Vol 400-401 ◽  
pp. 334-338 ◽  
Author(s):  
J. Gubicza ◽  
L. Balogh ◽  
R.J. Hellmig ◽  
Y. Estrin ◽  
T. Ungár

1989 ◽  
Vol 33 ◽  
pp. 397-402 ◽  
Author(s):  
Shin'ichi Ohya ◽  
Yasuo Yoshioka

When an x-ray diffraction profile Is measured for stress analysis or profile analysis by the use of a linear (straight line) position sensitive proportional counter (PSPC) , a convex-type background line is obtained because of the geometrical problem and the absorption of x-rays. Such phenomenon is remarkable when a wide angular range is set on a linear PSPC and it is, in particular, necessary to correct with a straight background for accurate measurement of diffraction angle or half-value breadth of the broadened diffraction profile.


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