PSI - Issue 37

I. Shardakov et al. / Procedia Structural Integrity 37 (2022) 1065–1072 I. Shardakov et al. / Structural Integrity Procedia 00 (2019) 000 – 000

1070

6

fluences was studied using spectrophotometry. Fig. 5b shows in relative units the level of absorption of the light signals with wavelengths of 357 nm (solid line) and 555 nm (dashed line) depending on the fluence value. It is known that the higher the level of signal absorption, the higher the level of carbonization of the surface layer (Kondyurin et al. (2006)). Thus, the graphs in Fig. 5b indicate an increase in the carbonization of the surface layer with an increase in the treatment fluence.

Figure 5. (a) Dependence of the elastic modulus of the carbonized layer on the treatment fluence; (b) Dependence of light absorption in relative units on the treatment fluence; wavelength: solid line - 357 nm, dotted line - 555 nm. Below are the data obtained in the study of the formation of cracks on the surface of the carbonized layer. These experiments were carried out in accordance with the technique described above. The photographs in Figure 6 show the surface of the carbonized layer at the moment of crack initiation during uniaxial deformation of the specimen. Frames a and b were obtained for the samples treated at different fluences.

Figure 6. Surface of the specimens at the moment of cracking under tension: (a) treatment fluence 10 15 ions / cm 2 , (b) 10 16 ions / cm 2 . The direction of deformation is indicated by arrow.

Fig. 7 shows the value of uniaxial deformation, which corresponds to the appearance of cracks in the carbonized layer. This value decreases significantly with an increase in the fluence. This dependence indicates a more pronounced manifestation of the brittle properties of the surface layer as the fluence increases. All cracks on the surface of the samples are located perpendicular to the direction of deformation.