PSI - Issue 74

Pavol Mikula et al. / Procedia Structural Integrity 74 (2025) 56–61 Pavol Mikula / Structural Integrity Procedia 00 ( 2025) 000–000

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individual diffraction profiles, it can be stated that the C-E procedure has a negligible influence on FWHM. Therefore, the main effect bringing about the increase of FWHM seen in Figs. 5c- 5e is brought about just by the RS deformation procedure. Moreover, the angular shift of the peak position expressed by the parameter ∆θ A (in radians) provides the value of the longitudinal strains ε = ( ∆ d S / d 0,S ) = - cot θ S ·( ∆θ A /2).

FWHM = (0.108 ± 0.002) deg ∆θ A = (-0.0114 ± 0.0007) deg

Ti-Gr 2 Standard sample φ = 8 mm 10 mm slit FWHM = (0.108 ± 0.004) deg

500

400

400

Ti-Gr 2 1 x C-E φ = 8 mm 10 mm slit

300

(a)

300

(b)

200

200

Intensity / 500 s

Intensity / 500 s

100

100

0

0

-0.4 -0.2

0.0

0.2

0.4

-0.4 -0.2

0.0

0.2

0.4

∆θ A / deg

∆θ A / deg

FWHM = (0.203 ± 0.005) deg ∆θ A = (+0.0249 ± 0.0008) deg

FWHM = (0.225 ± 0.004) deg ∆θ A = (+0.0249 ± 0.0005) deg

100 120 140

100 120 140

FWHM = (0.215 ± 0.004) deg ∆θ A = (0.0330 ± 0.0007) deg Ti-Gr 2 1 x C-E + RS φ = 4 mm 10 mm slit

70

Ti-Gr 2 3 x C-E + RK φ = 4 mm 10 mm slit

60

Ti-Gr 2 2 x C-E + RS φ = 4 mm 10 mm slit

50

(e)

(c)

0 20 40 60 80

0 20 40 60 80

(d)

40

30

Intensity / 500 s

Intensity / 500 s

Intensity / 500 s

20

10

-0.4 -0.2

0.0

0.2

0.4

-0.4 -0.2

0.0

0.2

0.4

-0.4 -0.2

0.0

0.2

0.4

∆θ A / deg

∆θ A / deg

∆θ A / deg

It can be stated that the presented method is feasible for the application of the diffraction profile analysis for characterizing plastic deformation of the polycrystalline Ti-Gr samples as has been suggested e.g. by Delhes et al. (1982) and Davydov et al. (2008). 6. Conclusions Feasibility studies of Ti-Gr 2 samples submitted to strong deformation procedures (C-E in combination with the RS method) by the high-resolution neutron diffraction were carried out. When comparing Figs. 5a and 5b, it has been found that the C-E procedure has practically no effect on the FWHM of the analyzer rocking curves and a very small measurable strain effect ( ∆ d S / d 0,S ) (in the direction of the length of the wire) apparent from the ∆θ A -peak shifts being in the vicinity of 10 -4 . On the other hand, a significant increase of FWHMs observed in the case of the diffraction profiles shown in Figs. 5c-5e are brought about by the RS plastic deformation procedure. The small mutual differences can be interpreted as a result of non-perfectly stable experimental conditions. It should also be pointed out, that as expected, the C-E + RS procedures create a strong texture resulting the fact that when situating the samples in the vertical position (see Fig. 2), the analyzer rocking curves were practically not measurable (see also the related curve in Fig. 3, where the reflection (101) is practically not visible). Therefore, it enabled us to measure analyzer rocking curves related to deformed samples only when set in the horizontal position. When they were set in the vertical position, diffraction signal was very weak and hardly separated from the experimental background. In this case, it should be pointed out that the titanium material has a very small scattering amplitude and therefore, the measurement is at the medium-power neutron source very demanding on the beam time (compare the measurement signal related to the standard α -Fe samples as shown in Fig. 4 and the Ti-Gr 2 samples shown in Fig. 5) and using the high-flux neutron source would be much more convenient. Nevertheless, it can be stated, that the introduced neutron diffraction method can offer further complementary information to that achieved by the other methods commonly used. Fig. 5. Analyzer rocking curves for a non-deformed standard sample – (a), the deformed one by the C-E method (1x) – (b) and 3 plastically samples deformed by C-E method (1x, 2x and 3x) in combination with RS - (c), (d) and (e), all set in the horizontal position.