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Lotkov A, Grishkov V, Laptev R, Mironov Y, Zhapova D, Girsova N, Gusarenko A, Barmina E, Kashina O. Crystal Structure Defects in Titanium Nickelide after Abc Pressing at Lowered Temperature. MATERIALS 2022; 15:ma15124298. [PMID: 35744353 PMCID: PMC9227948 DOI: 10.3390/ma15124298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 06/09/2022] [Accepted: 06/15/2022] [Indexed: 11/16/2022]
Abstract
The experimental results regarding the effect of warm (573 K) abc pressing with an increase in the specified true strain, e, up to 9.55, on the microstructure and crystal structure defects (dislocations, vacancies) of the Ti49.8Ni50.2 (at %) alloy are presented. It is shown that all samples (regardless of e) have a two-level microstructure. The grains–subgrains of the submicrocrystalline scale level are in the volumes of large grains. The average sizes of both large grains and subgrain grains decrease with increasing e to 9.55 (from 27 to 12 µm and from 0.36 to 0.13 µm, respectively). All samples had a two-phase state (rhombohedral R and monoclinic B19′ martensitic phases) at 295 K. The full-profile analysis of X-ray reflections of the B2 phase obtained at 393 K shows that the dislocation density increases from 1014 m−2 to 1015 m−2 after pressing with e = 1.84 and reaches 2·1015 m−2 when e increases to 9.55. It has been established by positron annihilation lifetime spectroscopy that dislocations are the main type of defects in initial samples and the only type of defects in samples after abc pressing. The lifetime of positrons trapped by dislocations is 166 ps, and the intensity of this component increases from 83% in the initial samples to 99.4% after pressing with e = 9.55. The initial samples contain a component with a positron lifetime of 192 ps (intensity 16.4%), which corresponds to the presence of monovacancies in the nickel sublattice of the B2 phase (concentration ≈10−5). This component is absent in the positron lifetime spectra in the samples after pressing. The results of the analysis of the Doppler broadening spectroscopy correlate with the data obtained by the positron annihilation lifetime spectroscopy.
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Affiliation(s)
- Aleksandr Lotkov
- Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia; (V.G.); (Y.M.); (D.Z.); (N.G.); (A.G.); (E.B.); (O.K.)
- Correspondence: ; Tel.: +7-382-249-26-96
| | - Victor Grishkov
- Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia; (V.G.); (Y.M.); (D.Z.); (N.G.); (A.G.); (E.B.); (O.K.)
| | - Roman Laptev
- Division for Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia;
| | - Yuri Mironov
- Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia; (V.G.); (Y.M.); (D.Z.); (N.G.); (A.G.); (E.B.); (O.K.)
| | - Dorzhima Zhapova
- Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia; (V.G.); (Y.M.); (D.Z.); (N.G.); (A.G.); (E.B.); (O.K.)
| | - Natalia Girsova
- Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia; (V.G.); (Y.M.); (D.Z.); (N.G.); (A.G.); (E.B.); (O.K.)
| | - Angelina Gusarenko
- Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia; (V.G.); (Y.M.); (D.Z.); (N.G.); (A.G.); (E.B.); (O.K.)
| | - Elena Barmina
- Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia; (V.G.); (Y.M.); (D.Z.); (N.G.); (A.G.); (E.B.); (O.K.)
| | - Olga Kashina
- Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Science, 634055 Tomsk, Russia; (V.G.); (Y.M.); (D.Z.); (N.G.); (A.G.); (E.B.); (O.K.)
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Li J, Laptev R, Bordulev I, Siemek K, Horodek P, Shen H, Lomygin A, Cui J. Positron Annihilation Spectroscopy Study of Metallic Materials after High-Speed Cutting. MATERIALS 2022; 15:ma15031017. [PMID: 35160960 PMCID: PMC8838609 DOI: 10.3390/ma15031017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/22/2022] [Accepted: 01/27/2022] [Indexed: 11/16/2022]
Abstract
During high-speed cutting, a white layer is often produced on the machined surfaces after mechanical machining, seriously affecting the mechanical properties. These properties are related to the material structure and the defects induced by cutting. However, there is a lack of research on the atomic-scale defects of the white layer. This paper studied the influence of cutting parameters, namely the feed rate, cutting speed and cutting depth, on atomic-scale defects induced by high-speed cutting in GCr15 steel. Positron annihilation studies showed typical plastically deformed or tempered carbon steel defects with additional vacancy cluster components. The quantity of these clusters changed with cutting parameters. Furthermore, significant changes were observed in the subsurface region up to 1 µm, occurring as a result of simultaneous phase transformations, deformation and thermal impacts. The predominant accumulation of only one type of atomic-scale defect was not observed.
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Affiliation(s)
- Jinquan Li
- School of Mechanical Engineering, Shenyang Ligong University, No.6 Nanping Center Road, Hunnan New District, Shenyang 110159, China;
- Correspondence: (J.L.); (R.L.); Tel.: +7-913-852-3733 (R.L.)
| | - Roman Laptev
- Division for Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (I.B.); (A.L.); (J.C.)
- Correspondence: (J.L.); (R.L.); Tel.: +7-913-852-3733 (R.L.)
| | - Iurii Bordulev
- Division for Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (I.B.); (A.L.); (J.C.)
| | - Krzysztof Siemek
- Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 Krakow, Poland; (K.S.); (P.H.)
- Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia
| | - Pawel Horodek
- Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 Krakow, Poland; (K.S.); (P.H.)
- Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia
| | - Haolun Shen
- School of Mechanical Engineering, Shenyang Ligong University, No.6 Nanping Center Road, Hunnan New District, Shenyang 110159, China;
| | - Anton Lomygin
- Division for Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (I.B.); (A.L.); (J.C.)
| | - Jian Cui
- Division for Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia; (I.B.); (A.L.); (J.C.)
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Abstract
The microstructure, martensitic transformations and crystal structure defects in the Ti50Ni47.3Fe2.7 (at%) alloy after equal-channel angular pressing (ECAP, angle 90°, route BC, 1–3 passes at T = 723 K) have been investigated. A homogeneous submicrocrystalline (SMC) structure (grains/subgrains about 300 nm) is observed after 3 ECAP passes. Crystal structure defects in the Ti49.4Ni50.6 (at%) alloy (8 ECAP passes, angle 120°, BC route, T = 723 K, grains/subgrains about 300 nm) and Ti50Ni47.3Fe2.7 (at%) alloy with SMC B2 structures after ECAP were studied by positron lifetime spectroscopy at the room temperature. The single component with the positron lifetime τ1 = 132 ps and τ1 = 140 ps were observed for positron lifetime spectra (PLS) obtained from ternary and binary, correspondingly, annealed alloys with coarse-grained structures. This τ1 values correspond to the lifetime of delocalized positrons in defect-free B2 phase. The two component PLS were found for all samples exposed by ECAP. The component with τ2 = 160 ps (annihilation of positrons trapped by dislocations) is observed for all samples after 1–8 ECAP passes. The component with τ3 = 305 ps (annihilation of positrons trapped by vacancy nanoclusters) was detected only after the first ECAP pass. The component with τ3 = 200 ps (annihilation of positrons trapped by vacancies in the Ti sublattice of B2 structure) is observed for all samples after 3–8 ECAP passes.
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