The topography of surface layers of 12Cr18Ni10Ti (AISI 321) steel after pulsed high-power Cn+ ion beams irradiation was investigated by scanning electron microscopy. A thin foil was prepared from the cross section of a crater with the use of a focused ion beam in the column of a two-beam electron-ion microscope. The microstructure and chemical composition of the crater were studied by transmission electron microscop

A. E. Ligachev

G. E. Remnev

G. V. Potemkin

M. V. Zhidkov

S. S. Manokhin

Yu. R. Kolobov

Inorganic Materials Applied Research

English

Zhidkov, M. V.

Ligachev, A. E.

Potemkin, G. V.

Manokhin, S. S.

Remnev, G. E.

DSpace at Belgorod State University

ISSN 2075-1133, Inorganic Materials: Applied Research, 2018, Vol. 9, No. 3, pp. 376–378. © Pleiades Publishing, Ltd., 2018.Original Russian Text © M.V. Zhidkov, A.E. Ligachev, G.V. Potemkin, S.S. Manokhin, G.E. Remnev, Yu.R. Kolobov, 2017, published in Fizika i Khimiya Obrabotki Materialov,2017, No. 6, pp. 18–21.EFFECTS OF ENERGY FLUXES ON MATERIALSStudy of the Structure of Crater at the Surface of 12Cr18Ni10Ti Steel Irradiated by High-Power Pulsed Ion BeamM. V. Zhidkova, *, A. E. Ligachevb, ***, G. V. Potemkinc, ****, S. S. Manokhina, d, **,G. E. Remnevc, *****, and Yu. R. Kolobova, d, ******aBelgorod State National Research University, Belgorod, 308015 RussiabProkhorov Institute of General Physics, Russian Academy of Sciences, Moscow, 119991 RussiacTomsk Polytechnic University, Tomsk, 634050 RussiadInstitute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia*e-mail: zhidkov@bsu.edu.ru**e-mail: manohin@bk.ru***e-mail: carbin@yandex.ru****e-mail: ep.gvp@yandex.ru*****e-mail: remnev06@mail.ru******e-mail: kolobov@bsu.edu.ruReceived October 5, 2017Abstract—The topography of surface layers of 12Cr18Ni10Ti (AISI 321) steel after pulsed high-power Cn+ ion beamsirradiation was investigated by scanning electron microscopy. A thin foil was prepared from the cross section of a cra-ter with the use of a focused ion beam in the column of a two-beam electron-ion microscope. The microstructureand chemical composition of the crater were studied by transmission electron microscopy. It is shown that the near-surface layer (~2 μm in depth) of the crater is represented by an area of columnar grains elongated in the direction ofthe surface. Under the layer of columnar grains, the region with equiaxial submicrocrystalline grains is situated.Keywords: high-power pulsed ion beams, surface, crater, structureDOI: 10.1134/S2075113318030322INTRODUCTIONThe mechanism of the appearance of craters on thesurface of metals after the action of high-power pulsedion beams (HPPIB) is still a subject of debate. In thisconnection, one can hope that an experimental study ofthe regularities and structural mechanisms of the pro-cesses of crater formation will help optimize the process-ing regimes of HPPIB materials and formulate practicalrecommendations for obtaining materials and productswith given surface properties and near-surface layers.In this paper, the microstructure of a crater formedon the surface of 12Cr18Ni10Ti stainless steel afterirradiation with a high-power pulsed ion beam is stud-ied. The test surface was ground and polished to “mir-ror gloss” on a LaboPol-5 (Struers) installation. Theirradiation was carried out at the TEMP accelerator[1] with a 250-keV Cn+ ion beam at the pressure ofresidual gases in the chamber of (4–5) × 10–2 Pa. Thepulse duration was ~100 ns, and the current density inthe pulse was 150–200 A/cm2. The surface was sub-jected to ten pulses at the energy density in a pulse of~3 J/cm2. The topography of the surface of the irradi-ated sample was studied with a Zeiss Ultraplus scan-ning electron microscope. The thin foil cut from thecross section of the crater, obtained by ionic thinningof the crater material with a focused ion beam on aFEI Helios 660 scanning electron microscope, wasexamined on a Tecnai G2 20F S-T (FEI) transmissionelectron microscope.For craters formed on the surface, whose densitywas not less than 1 × 104 cm–2, central symmetry andthe presence of a ring structure are characteristic.There are craters both with a pronounced ring struc-ture and with weak and diffuse peripheral rings, whilein the center of the crater there may be either a cavityor a peak. All this creates a visible variety of shapes andsizes of surface defects (Fig. 1a).To study the internal structure of the crater, anannular single crater of ~40 μm in size with a cavity inthe center was selected (Fig. 1b). As a result of succes-sive ion thinning, a thin (~90 nm) foil of the cross sec-tion of the crater with an area of interest of 103 μm wasobtained (inset in Fig. 1b).Figure 2 shows the structure of the cross section ofthe crater. According to the data of transmission scan-ning electron microscopy, the surface layer of the cra-376INORGANIC MATERIALS: APPLIED RESEARCH  Vol.STUDY OF THE STRUCTURE OF CRATER AT THE SURFACE 377Fig. 1. Topography of the surface of 12Cr18Ni10Ti steel after the action of ten pulses of high-power pulsed ion beam at energydensity of 3 J/cm2 (a) and crater coated with Pt protective layer (b). Tilt angle of specimen in the microscope column is 52°. Imageof the foil ~90 nm in thickness extracted from the specimen is presented in the inset.(b)200 µm5 µm1 µm(a)Fig. 2. Microstructure of cross section of the crater (a) andchart of it (b).(b)1 µmPeriphery of the crater (a)Pt residues Center of the crater12 3ter consists of columnar grains extended in the direc-tion of the surface with an average length of ~2 μm andthe value of the grain nonuniformity coefficient(GNC) greater than 3 (Fig. 2, region 1, Fig. 3a). Thevalue of GNC decreases with shifting from the periph-eral ring of the crater to its central part (Fig. 2, region 3,Fig. 3c). Under the layer of elongated crystallites inthe crater, there is a region with equiaxial submicro-crystalline (SMC) grains, whose average size is 250 nm(Fig. 2, region 2, Fig. 3b).The character of the formed structure definitelyindicates the progress of melting and superfast crystal-lization in a thin near-surface layer in the process ofcrater formation. The formation of SMC grains with afairly high density of dislocations under a layer ofcolumnar crystals can also be indicative of the shock-wave mechanism of the action of HPPIB on the near-surface layer of the metal being processed.Currently, there are various assumptions about thenature and mechanisms of the formation of craters—inhomogeneity of the ion beam density in the pulse[2], the presence of gas impurities in the material andthe escape of gas bubbles to the molten surface [3], theeffect of the recoil momentum produced upon localmelting and evaporation of the target [4], the formation 9  No. 3  2018378 ZHIDKOV et al.Fig. 3. Microstructure of different areas of the crater:(a) periphery (Fig. 2a, area 1); (b) periphery (Fig. 2a, area 2);(c) center (Fig. 2a, area 3). Digitized highlighters designatethe areas for elemental microanalysis.(b)200 nm200 nm200 nm(c)(a)1Pt2345Table 1. Elemental composition of different areas of the crater,wt %. Areas analyzed are emphasized by highlighters in Fig. 3Area of analysis Ni Cr Fe1 9.3 14.6 73.22 7 15.7 75.93 19.5 2.7 76.34 15.5 4.3 78.85 9.5 4.8 84.2of a plasma torch followed by the appearance of instabil-ity of the plasma–melt boundary [5]. Within the frame-work of the model [5], it is also shown that, in the processof crater formation under its surface, stress fields arisethat exceed the yield strength, which can be responsiblefor structural changes in the near-surface layer.According to the EMF data (Table 1), in the centralregion the crater, redistribution of alloying elementsINORGANIC MAToccurs with the emergence of areas with a high content ofnickel and low content of chromium. In the process ofcrater formation, significant vaporization of chromium isalso possible owing to high elasticity of its vapor.CONCLUSIONSDuring HPPIB irradiation of 12Cr18Ni10Ti steel(3 J/cm2, 10 pulses), craters with density of at least104 cm–2 are formed on its surface. Electron micro-scopic studies of the cross section of the crater haveshown that a zone of columnar grains stretched towardthe surface is formed in the near-surface crater layerwith a depth of ~2 μm, and a region with equiaxialSMC grains is formed under it.ACKNOWLEDGMENTSThe work on the crater study by the TEM method wassupported by the State Task of the Ministry of Educationto Higher Education Institutions no. 3.3144.2017/ПЧ.The work on surface processing of the samples at theTEMP installation was supported by the Russian Foun-dation for Basic Research, grant no. 14-08-00632.REFERENCES1. Isakov, I.F., Kolodii, V.N., Opekunov, M.S., Matvi-enko, V.M., Pechenkin, S.A., Remnev, G.E., andUsov, Yu.P., Sources of high power ion beams for tech-nological applications, Vacuum, 1991, vol. 42, nos. 1–2,pp. 159–162.2. Pogrebnyak, A.D. and Kul’ment’eva, O.P., Structure-phase transformations in near-surface layers and propertiesof metal materials after pulse treatment by particle beams,Fiz. Inzh. Poverkhn., 2003, vol. 1, no. 2, pp. 110–136.3. Chernov, I.P., Beloglazova, P.A., Berezneeva, E.V.,Kireeva, I.V., Pushilina, N.S., Remnyov, G.E., andStepanova, E.N., Properties of the VT1-0 titanium sur-face modified by a pulsed ion beam, Tech. Phys., 2015,vol. 60, no. 7, pp. 1039–1043.4. Korotaev, A.D., Tyumentsev, A.N., Pinzhin, Yu.P.,and Remnev, G.E., Features of the morphology, defectsubstructure, and phase composition of metal and alloysurfaces upon high-power ion beam irradiation, Surf.Coat. Technol., 2004, vol. 185, pp. 38–49.5. Volkov, N.B., Maier, A.E., and Yalovets, A.P., On themechanism of cratering on solid surfaces exposed to anintense charged particle beam, Tech. Phys., 2002,vol. 47, no. 8, pp. 968–977.Translated by Sh. GalyaltdinovERIALS: APPLIED RESEARCH  Vol. 9  No. 3  2018

Study of the structure of crater at the surface of 12Cr18Ni10Ti steel irradiated by high-power pulsed ion beam

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Study of the Structure of Crater at the Surface of 12Cr18Ni10Ti Steel Irradiated by High-Power Pulsed Ion Beam

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Study of the structure of crater at the surface of 12Cr18Ni10Ti steel irradiated by high-power pulsed ion beam

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