Current dislocation density measurements include the use of many microscopy techniques (TEM, EBSD, XRD, ECCI, etc.). What is the most accepted measurement technique and what are the range of measuring capabilities?
XRD Microscopy - NDE, non-contact, non-intrusive, non-invasive, in situ! X-ray Rocking Curve measurements and mapping. See example of ZnSe (224) Bragg Peak Sift and FWHM maps. This method measures the deviation from IDEAL BRAGG CONDITION and correlates it to dislocation density.
Bragg Peak Broadening: Is a measure of the mosaic structure or dislocation/defect density in the diffracting domain. For a simple Gaussian distribution the FWHM may be realted to the dislocation density through the Berger's Vector as following:
Dislocation Density, ρ=β^2/9b^2 for a Gaussian distribution, b=Burger’s Vector, ρ-Dislocation Density, integral breadth, β, is related to the FWHM peak width, H, by β = 0.5 H (π / log e 2)^1/2
References:
Some helpful references:
XRD Basics: http://web.pdx.edu/~pmoeck/phy381/Topic5a-XRD.pdf
Line Profile Analyses: http://pd.chem.ucl.ac.uk/pdnn/peaks/gauss.htm
All of Dr. Sigmund Weissmann’s relevant references: (XRD Rocking Curve Analysis)
a). R. Yazici, W. Mayo, T. Takemoto & S. Weissmann (1983). Defect structure analysis of polycrystalline materials by computer-controlled double-crystal diffractometer with position-sensitive detector. J. Appl. Cryst. 16, 89-95.
b). W. Mayo, R. Yazici, T. Takemoto & S. Weissmann (1981). Defect structure analysis of polycrystalline materials by computer -controlled double-crystal diffractometer and position-sensitive detector. Acta Cryst. A37, C253
Photographic Film/Topography and RC Analysis:
c). Rocking Curve Analysis - Dr. Sigmund Weissmann (Rutgers) Acta Cryst. (1954). 7, 729-732 [ doi:10.1107/S0365110X54002216 ]An X-ray diffraction method for the study of substructure of crystals J. Intrater and S. Weissmann http://scripts.iucr.org/cgi-bin/paper?S0365110X54002216
d). Acta Cryst. (1954). 7, 733-737 [ doi:10.1107/S0365110X54002228 ]An X-ray study of the substructure of fine-grained aluminium S. Weissmann and D. L. Evans; http://scripts.iucr.org/cgi-bin/paper?S0365110X54002228
e). J. Intrater & S. Weissmann (1954). An X-ray diffraction method for the study of substructure of crystals. Acta Cryst. 7, 729-732.
f). S. Weissmann, Z. H. Kalman, J. Chaudhuri & G. J. Weng (1981). Determination of strain concentration and strain interaction by intensity measurements of X-ray topographs. Acta Cryst. A37, C247.
g). J. Chaudhuri, Z. H. Kalman, G. J. Weng & S. Weissmann (1982). Determination of the strain concentration factors around holes and inclusions in crystals by X-ray topography. J. Appl. Cryst. 15, 423-429.
h). H. L. Glass & S. Weissmann (1969). Synergy of line profile analysis and selected area topography by the X-ray divergent beam method. J. Appl. Cryst. 2, 200-209.
i). T. Imura, S. Weissmann & J. J. Slade Jnr (1962). A study of age-hardening of Al-3.85% Cu by the divergent X-ray beam method. Acta Cryst. 15, 786-793.
j). Z. H. Kalman, J. Chaudhuri, G. J. Weng & S. Weissmann (1980). Determination of strain concentration by microfluorescent densitometry of X-ray topography: A bridge between microfracture and continuum mechanics. J. Appl. Cryst. 13, 290-296.
k). Z. H. Kalman & S. Weissmann (1983). On the X-ray reflectivity of elastically bent perfect crystals. J. Appl. Cryst. 16, 295-303.
l). Z. H. Kalman & S. Weissmann (1979). Determination of strain distribution in elastically bent materials by X-ray intensity measurement. J. Appl. Cryst. 12, 209-220.
m). H. Y. Liu, G. J. Weng & S. Weissmann (1982). Determination of notch-tip plasticity by X-ray diffraction and comparison to continuum mechanics analysis. J. Appl. Cryst. 15, 594-601. .
n). B. A. Newman & S. Weissmann (1968). Strain inhomogeneities in lightly compressed tungsten crystals. J. Appl. Cryst. 1, 139-145.
o). S. Weissmann & D. L. Evans (1954). An X-ray study of the substructure of fine-grained aluminium. Acta Cryst. 7, 733-737.
p). S. Weissmann, V. A. Greenhut, J. Chaudhuri & Z. H. Kalman (1983). Quantitative analysis of intensitities in X-ray topographs by enhanced microfluorescence. J. Appl. Cryst. 16, 606-610.
q). L. D. Calvert, T. C. Huang, M. H. Mueller, P. L. Wallace & S. Weissmann (1993). New ICDD metals and alloys indexes, a powerful materials research tool. Acta Cryst. A49, c443-c444.
r). R. J. Schutz, S. Weissmann & J. Yaniero (1981). The fabrication of a dual-element X-ray divergent-beam target. J. Appl. Cryst. 14, 352-353.
Ravi - [email protected] 732.429.3538
http://www.flickr.com/photos/85210325@N04/8493232400/in/photostream
Hello Travis,
I think the most applied technique is still XRD. For microstructure analysis of single crystals I used also FIP. I think one should look for direct measuring methods like TEM or semiconductors IR combining them with numerical image analysis. Using TEM the analysis even of small specimens have been very time comsuming. I wonder about the present state of technology in this field (TEM, image analysis).
Using TEM directly you can measure the dislocation density. But the TEM sample preparation is difficult. A lot of care is needed to prepare the TEM sample, otherwise while sample preparation extra dislocation is introduce. XRD is also a good tool but not much accurate.
Hello Travis,
As Mahanthy answer, Using TEM is one of the best way to measure dislocation density compare to XRD.In case of sample preparation we may introduce some dislocations so that there may be change in dislocation density.
Depending on what you are doing, TEM and XRD are the two most common methods, one for small probing region with details and one for large region at the expense of spatial resolution. However, EBSD have bridged these two methods and provide good combination of spatial and angular resolutions. Brent Adams at your university is one of the top experts on using EBSD to measure geometrically necessary dislocation(GND) density.
Depend on yours purposes: In the case, you need local informations on interactions of dislocations with structure, the best tool is Transmision Electron Microscopy. In the characterisations of the dislocations behaviour after changing of some metallurgical variables the better technique is XRD. The information is comming from 1x1cm area and the information is summation on this region. Both together, can characterized almost all information you needs. The answer from Mr. Jun Jiang is good for you.
XRD Microscopy - NDE, non-contact, non-intrusive, non-invasive, in situ! X-ray Rocking Curve measurements and mapping. See example of ZnSe (224) Bragg Peak Sift and FWHM maps. This method measures the deviation from IDEAL BRAGG CONDITION and correlates it to dislocation density.
Bragg Peak Broadening: Is a measure of the mosaic structure or dislocation/defect density in the diffracting domain. For a simple Gaussian distribution the FWHM may be realted to the dislocation density through the Berger's Vector as following:
Dislocation Density, ρ=β^2/9b^2 for a Gaussian distribution, b=Burger’s Vector, ρ-Dislocation Density, integral breadth, β, is related to the FWHM peak width, H, by β = 0.5 H (π / log e 2)^1/2
References:
Some helpful references:
XRD Basics: http://web.pdx.edu/~pmoeck/phy381/Topic5a-XRD.pdf
Line Profile Analyses: http://pd.chem.ucl.ac.uk/pdnn/peaks/gauss.htm
All of Dr. Sigmund Weissmann’s relevant references: (XRD Rocking Curve Analysis)
a). R. Yazici, W. Mayo, T. Takemoto & S. Weissmann (1983). Defect structure analysis of polycrystalline materials by computer-controlled double-crystal diffractometer with position-sensitive detector. J. Appl. Cryst. 16, 89-95.
b). W. Mayo, R. Yazici, T. Takemoto & S. Weissmann (1981). Defect structure analysis of polycrystalline materials by computer -controlled double-crystal diffractometer and position-sensitive detector. Acta Cryst. A37, C253
Photographic Film/Topography and RC Analysis:
c). Rocking Curve Analysis - Dr. Sigmund Weissmann (Rutgers) Acta Cryst. (1954). 7, 729-732 [ doi:10.1107/S0365110X54002216 ]An X-ray diffraction method for the study of substructure of crystals J. Intrater and S. Weissmann http://scripts.iucr.org/cgi-bin/paper?S0365110X54002216
d). Acta Cryst. (1954). 7, 733-737 [ doi:10.1107/S0365110X54002228 ]An X-ray study of the substructure of fine-grained aluminium S. Weissmann and D. L. Evans; http://scripts.iucr.org/cgi-bin/paper?S0365110X54002228
e). J. Intrater & S. Weissmann (1954). An X-ray diffraction method for the study of substructure of crystals. Acta Cryst. 7, 729-732.
f). S. Weissmann, Z. H. Kalman, J. Chaudhuri & G. J. Weng (1981). Determination of strain concentration and strain interaction by intensity measurements of X-ray topographs. Acta Cryst. A37, C247.
g). J. Chaudhuri, Z. H. Kalman, G. J. Weng & S. Weissmann (1982). Determination of the strain concentration factors around holes and inclusions in crystals by X-ray topography. J. Appl. Cryst. 15, 423-429.
h). H. L. Glass & S. Weissmann (1969). Synergy of line profile analysis and selected area topography by the X-ray divergent beam method. J. Appl. Cryst. 2, 200-209.
i). T. Imura, S. Weissmann & J. J. Slade Jnr (1962). A study of age-hardening of Al-3.85% Cu by the divergent X-ray beam method. Acta Cryst. 15, 786-793.
j). Z. H. Kalman, J. Chaudhuri, G. J. Weng & S. Weissmann (1980). Determination of strain concentration by microfluorescent densitometry of X-ray topography: A bridge between microfracture and continuum mechanics. J. Appl. Cryst. 13, 290-296.
k). Z. H. Kalman & S. Weissmann (1983). On the X-ray reflectivity of elastically bent perfect crystals. J. Appl. Cryst. 16, 295-303.
l). Z. H. Kalman & S. Weissmann (1979). Determination of strain distribution in elastically bent materials by X-ray intensity measurement. J. Appl. Cryst. 12, 209-220.
m). H. Y. Liu, G. J. Weng & S. Weissmann (1982). Determination of notch-tip plasticity by X-ray diffraction and comparison to continuum mechanics analysis. J. Appl. Cryst. 15, 594-601. .
n). B. A. Newman & S. Weissmann (1968). Strain inhomogeneities in lightly compressed tungsten crystals. J. Appl. Cryst. 1, 139-145.
o). S. Weissmann & D. L. Evans (1954). An X-ray study of the substructure of fine-grained aluminium. Acta Cryst. 7, 733-737.
p). S. Weissmann, V. A. Greenhut, J. Chaudhuri & Z. H. Kalman (1983). Quantitative analysis of intensitities in X-ray topographs by enhanced microfluorescence. J. Appl. Cryst. 16, 606-610.
q). L. D. Calvert, T. C. Huang, M. H. Mueller, P. L. Wallace & S. Weissmann (1993). New ICDD metals and alloys indexes, a powerful materials research tool. Acta Cryst. A49, c443-c444.
r). R. J. Schutz, S. Weissmann & J. Yaniero (1981). The fabrication of a dual-element X-ray divergent-beam target. J. Appl. Cryst. 14, 352-353.
Ravi - [email protected] 732.429.3538
http://www.flickr.com/photos/85210325@N04/8493232400/in/photostream
The challenge with SEM, TEM, STEM etc. is the fact that one needs to decimate the very sample being examined.
EPD is an excellent method used for centuries to estimate dislocation density. There are several challenges with this method as well. Check out this Linkedin discussion for further details:
http://www.linkedin.com/groupItem?view=&gid=2683600&type=member&item=188581023&qid=6bc615f9-895f-4044-8bb9-474316cc8e9e&trk=group_items_see_more-0-b-ttl
Hi Travis
Dislocation density is possible with XRD technique or With the help of Motic Software we can measure dislocation density.
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