LABORATORY OF X-RAY DIFFRACTION (L-3)

Authorisation:

Address:

Aleksander Krupkowski Institute

of Metallurgy and Materials Science,

Polish Academy of Sciences,

25, Reymonta Str., 30-59 Kraków,

phone: (48)(12) 295 28 00,

fax: (48)(12) 295 28 04,

e-mail: Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć. ,

Associate Prof. Jan Bonarski, PhD, DSc, Eng. (n Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć. )

Marcin Bijak, PhD, Eng.

Anna Góral, PhD, Eng.

Stanisław Kotas, Eng.

Roman Major, PhD, Eng.

Leszek Tarkowski, PhD, Eng.

 

Certified procedures:

1. X-Ray Phase Analysis (P/19/IB-08 edition 03 of 25.07.2003)

The procedure covers both qualitative (phase identification) and quantitative (volume fractions) phase analyses, the determination of crystal lattice parameters and estimation of the crystallite size in tested materials. An example of X-ray diffraction pattern is shown in Fig. 1. Remote control of measurement and data processing is realized by means of a computer system, which uses Philips APD program and crystallographic JCPDS database.

Fig. 1. X-ray diffraction pattern of a mineral rock, registered with monochromatic CoKa beam. [IMIM PAN, Kraków (2002)]. 

2. X-ray Diffraction Stress Analysis (P/19/IB-9 edition 03 of 25.07.2003)

The procedure subject is residual stresses measurement indirectly, by means of a non destructive X-ray diffraction method. The so called sin²y method is based on displacement effect diffraction lines occurring in stressed material with crystalline structure. The residual stress measurement is carried out on a flat surface of sample, which linear dimensions do not exceed value: 70 x 20 x 8 mm. A whole constructional element or its selected fragment can be the sample. When cutting out the sample, care should be taken, in order not to disturb original state of stresses. The examined surface requires non-mechanical treatment, only chemical etching is permissible.

Both, determined measurement parameters and location of diffraction lines apart from the assumed angles y are realized by means of the firm APD program for diffraction phase analysis. Possible precision of the analysis depends on the material examined and it is determined individually in an experimental way regarding a nominal position of determined diffraction lines.

The experimental data of interplanar distances d_hkl and X-ray elastic constants for the examined material are the input data for a computer program calculating the value of the residual stresses. The program is at disposal of the L-3 laboratory. X-ray elastic constants are adjusted (matched) based on the subject literature, for example: monograph: G. Simmons, H. Wang “Single Crystal Elastic Constants and Calculated Aggregate Properties”, The M.I.T Press (1971) or other works available at the moment.

An example of the measurement results, transformed into lattice parameters is shown in Fig. 2 as a plot of d_hkl = f(sin²(y)

Fig. 2. The plot of the relationship d_hkl = f(sin²(y) for the ŁH15 bearing steel.

The results of the internal strains are considered correct if they are calculated with error not larger than 5 %. The calculation program contains the c ² statistical test, and a required accuracy is achieved at c²≤2.3.

3. X-Ray Diffraction Texture Analysis (P/19/IB-10 edition 03 of 25.07.2003)

It consists in recording diffraction effects and processing experimental data, which make possible to investigate the distribution of crystallographic orientation on the basis of the following characteristics, illustrated also in Fig. 2-5:

¨ incomplete pole figures registered by Schulz back-reflection method,

¨ orientation distribution function (ODF),

¨ complete pole figures, calculated from texture function,

¨ inverse pole figures.

Measurement and data acquisition control is carried out on our own devices, and following the PHIL and TEX computer programmes. Data are processed with our own computer programmes (DAM, PSD-TRAN), implementing our own methods (ESA, ADC).

Fig. 3. Complete pole figure of severely plastically deformed copper with two texture components marked. [IMIM PAN, Kraków (2002)]. 

 

Fig. 4. Incomplete 100 pole figures of titanium after equal channel angular pressing: experimental (left) and calculated from the ODF (right). [IMIM PAN, Kraków (2002)].

 

Fig. 5. Distribution (ODF section: j₂= 45⁰ deep-drawing ferritic steel. [IMIM PAN, Kraków (2000)]

Fig. 6. Experimental (upper), calculated (middle) and inverse (lower) pole figure (111) of Cu cold deformed up to 65 % [IMIM PAN, Kraków (2000)]. 

 

Apparatus:
The experimental tests resulting from the above-described investigation procedures are performed on:

- a two-stand Philips X-ray PW 1710 and PW 1830 diffractometer with X'Pert system and equipped with ATC-3 texture goniometer (see Fig. 7)

- D8 Discover Bruker diffractometer with polycapilar beam optics equipped with open Euler goniometer with a stage for scanning the specimen in two mutually perpendicular directions in the range of ± 40 mm.

Standard procedure consists in filtering Ka–series of Co target radiation. If necessary, Mo, Cu or Cr targets can be applied as well. Diffracted beam monochromatization applied in the phase analysis is accomplished by means of a graphite monochromator. The texture analysis uses a beam formation system, which enables changing its geometrical parameters, depending on the tested material. Nominally, the apparatus is equipped with two independent arrangements of proportional detectors 

 

 

Fig. 7. Two-stand Philips X-ray diffractometer. [IMIM PAN, Kraków (2002)].

Preparation of samples for testing.

 

 

The geometrical dimensions of samples for the above-mentioned X-ray testing should allow them to be fitted in a cylinder 32 mm in diameter and 8 mm in height. The sample surface to be tested has to be smooth and clean. Depending on the kind of material and type of analysis, the mechanical surface treatment (grinding, cutting) and polishing on discs and abrasive papers with final gradation smaller than 600 should be applied to the sample. In justified cases, the surface should be additionally polished mechanically or electrochemically.

Persons interested in co-operation should contact:

The Head of the Laboratory L-3:
Jan Bonarski, PhD DSc
phone: (0-12) 295 28 71
e-mail: Adres poczty elektronicznej jest chroniony przed robotami spamującymi. W przeglądarce musi być włączona obsługa JavaScript, żeby go zobaczyć.

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