TY - CHAP AU - Beke, Dezső AU - Cserháti, Csaba TI - Kinetics of Surface Segregation in Alloys: Formation of Metastable States with Anti-Phase Boundaries Near the Surface T2 - Advances in Physical Metallurgy PB - CRC Press CY - London SN - 9781003424000 PY - 2023 SP - 360 EP - 367 PG - 8 DO - 10.1201/9781003424000-46 UR - https://m2.mtmt.hu/api/publication/34576321 ID - 34576321 LA - English DB - MTMT ER - TY - JOUR AU - Kamel, Sarah M. AU - Daróczi, Lajos AU - Tóth, László Zoltán AU - Panchenko, Elena AU - Chumljakov, Yuriy I. AU - Mohareb, Nora Samy Sdky AU - Beke, Dezső TI - Acoustic emission and DSC investigations of anomalous stress-stain curves and burst like shape recovery of Ni49Fe18Ga27Co6 shape memory single crystals JF - INTERMETALLICS J2 - INTERMETALLICS VL - 159 PY - 2023 PG - 13 SN - 0966-9795 DO - 10.1016/j.intermet.2023.107932 UR - https://m2.mtmt.hu/api/publication/33786706 ID - 33786706 N1 - Department of Solid State Physics, Doctoral School of Physics, Faculty of Science and Technology, University of Debrecen, P. O. Box 400, Debrecen, H-4002, Hungary Physics Department, Faculty of Science Ain Shams University, Abbassia, Cairo, 11566, Egypt Siberian Physical Technical Institute, Tomsk State University, Tomsk, 634050, Russian Federation Department of Physics, Faculty of Education, Ain Shams University, Roxy, Cairo, 11341, Egypt Export Date: 31 May 2023 CODEN: IERME Correspondence Address: Beke, D.L.; Department of Solid State Physics, P. O. Box 400, Hungary; email: dbeke@delfin.unideb.hu AB - Simultaneous acoustic emission, AE, and DSC measurements under compression along [110]A direction were carried out on Ni49Fe18Ga27Co6 shape memory single crystals. The compression resulted in anomalous stressstrain loops with stress drops/jumps on it, reflecting a sudden formation/dissolution of a more stable (detwinned) martensite structural modification than the thermally induced (twinned) one. The final detwinned martensite, obtained below a certain temperature, was stable even after downloading: during heating it showed a burst-like recovery at about 35K higher transformation temperature than that of the thermally induced one, with an audible click. It was obtained that the number of acoustic events showed strong asymmetry: e.g. for stress induced transformations the number of hits for uploading was larger. Simultaneous measurements of stress-time curves and AE versus time revealed that in the nucleation/dissolution processes in both (up and down) directions, as an intermediate step, the twinned martensite was first formed and resulted in additional AE events. This was interpreted by the easy as well as difficult nucleation of the twinned and detwinned martensites, respectively. The stress drops on the uploading stress-strain curve were attributed to subsequent nucleation of the detwinned martensite from the twinned modification and were followed by a sharp decrease of the AE activity. This indicated that the formation of detwinned martensite is a sudden, fast process and can take place without significant elastic energy storage. This was also in agreement with the fact that during burst like thermal recovery the width of the transition was very small (Af ≅ As). Similarly, during downloading the stress jumps were interpreted as sudden dissolutions of the detwinned phase by retwinning and at all stress jumps there were local maxima on the AE activity curve. LA - English DB - MTMT ER - TY - JOUR AU - Tóth, László Zoltán AU - Bronstein, Emil AU - Daróczi, Lajos AU - Shilo, Doron AU - Beke, Dezső TI - Scaling of Average Avalanche Shapes for Acoustic Emission during Jerky Motion of Single Twin Boundary in Single-Crystalline Ni2MnGa JF - MATERIALS J2 - MATERIALS VL - 16 PY - 2023 IS - 5 SN - 1996-1944 DO - 10.3390/ma16052089 UR - https://m2.mtmt.hu/api/publication/33745669 ID - 33745669 AB - Temporal average shapes of crackling noise avalanches, U(t) (U is the detected parameter proportional to the interface velocity), have self-similar behavior, and it is expected that by appropriate normalization, they can be scaled together according to a universal scaling function. There are also universal scaling relations between the avalanche parameters (amplitude, A, energy, E, size (area), S, and duration, T), which in the mean field theory (MFT) have the form E∝A3, S∝A2, S∝T2. Recently, it turned out that normalizing the theoretically predicted average U(t) function at a fixed size, U(t)=atexp−bt2 (a and b are non-universal, material-dependent constants) by A and the rising time, R, a universal function can be obtained for acoustic emission (AE) avalanches emitted during interface motions in martensitic transformations, using the relation R~A1−φ too, where φ is a mechanism-dependent constant. It was shown that φ also appears in the scaling relations E~A3−φ and S~A2−φ, in accordance with the enigma for AE, that the above exponents are close to 2 and 1, respectively (in the MFT limit, i.e., with φ= 0, they are 3 and 2, respectively). In this paper, we analyze these properties for acoustic emission measurements carried out during the jerky motion of a single twin boundary in a Ni50Mn28.5Ga21.5 single crystal during slow compression. We show that calculating from the above-mentioned relations and normalizing the time axis of the average avalanche shapes with A1−φ, and the voltage axis with A, the averaged avalanche shapes for the fixed area are well scaled together for different size ranges. These have similar universal shapes as those obtained for the intermittent motion of austenite/martensite interfaces in two different shape memory alloys. The averaged shapes for a fixed duration, although they could be acceptably scaled together, showed a strong positive asymmetry (the avalanches decelerate much slower than they accelerate) and thus did not show a shape reminiscent of an inverted parabola, predicted by the MFT. For comparison, the above scaling exponents were also calculated from simultaneously measured magnetic emission data. It was obtained that the φ values are in accordance with theoretical predictions going beyond the MFT, but the AE results for φ are characteristically different from these, supporting that the well-known enigma for AE is related to this deviation. LA - English DB - MTMT ER - TY - JOUR AU - Beke, Dezső AU - Kamel, S.M. AU - Daróczi, Lajos AU - Tóth, László Zoltán TI - Thermodynamic Analysis of Anomalous Shape of Stress–Strain Curves for Shape Memory Alloys JF - MATERIALS J2 - MATERIALS VL - 15 PY - 2022 IS - 24 SN - 1996-1944 DO - 10.3390/ma15249010 UR - https://m2.mtmt.hu/api/publication/33539708 ID - 33539708 N1 - Department of Solid State Physics, University of Debrecen, P.O. Box 400, Debrecen, H-4002, Hungary Physics Department, Faculty of Science, Ain Shams University, Cairo, 11566, Egypt Export Date: 3 January 2023 Correspondence Address: Beke, D.L.; Department of Solid State Physics, P.O. Box 400, Hungary; email: dbeke@science.unideb.hu LA - English DB - MTMT ER - TY - JOUR AU - Tóth, László Zoltán AU - Daróczi, Lajos AU - Elrasasi, T.Y. AU - Beke, Dezső TI - Clustering Characterization of Acoustic Emission Signals Belonging to Twinning and Dislocation Slip during Plastic Deformation of Polycrystalline Sn JF - MATERIALS J2 - MATERIALS VL - 15 PY - 2022 IS - 19 SN - 1996-1944 DO - 10.3390/ma15196696 UR - https://m2.mtmt.hu/api/publication/33205595 ID - 33205595 N1 - Department of Solid State Physics, University of Debrecen, P.O. Box 400, Debrecen, H-4002, Hungary Department of Physics, Faculty of Science, Benha University, Benha, 13518, Egypt Export Date: 3 November 2022 Correspondence Address: Tóth, L.Z.; Department of Solid State Physics, P.O. Box 400, Hungary; email: toth.laszlo@science.unideb.hu Correspondence Address: Beke, D.L.; Department of Solid State Physics, P.O. Box 400, Hungary; email: dbeke@science.unideb.hu LA - English DB - MTMT ER - TY - JOUR AU - Kamel, S.M. AU - Mohareb, Nora Samy Sdky AU - Tóth, László Zoltán AU - Daróczi, Lajos AU - Beke, Dezső TI - Denouement of the Energy-Amplitude and Size-Amplitude Enigma for Acoustic-Emission Investigations of Materials JF - MATERIALS J2 - MATERIALS VL - 15 PY - 2022 IS - 13 SN - 1996-1944 DO - 10.3390/ma15134556 UR - https://m2.mtmt.hu/api/publication/33051601 ID - 33051601 AB - There are many systems producing crackling noise (avalanches) in materials. Temporal shapes of avalanches, U(t) (U is the detected voltage signal, t is the time), have self-similar behaviour and the normalized U(t) function (e.g., dividing both the values of U and t by S-1/2 , where S is the avalanche area), averaged for fixed S, should be the same, independently of the type of materials or avalanche mechanisms. However, there are experimental evidences that the temporal shapes of avalanches do not scale completely in a universal way. The self-similarity also leads to universal power-law-scaling relations, e.g., between the energy, E, and the peak amplitude, A(m), or between S and A(m). There are well-known enigmas, where the above exponents in acoustic emission measurements are rather close to 2 and 1, respectively, instead of E similar to A(m)(3) and S similar to A(m)(2), obtained from the mean field theory, MFT. We show, using a theoretically predicted averaged function for the fixed avalanche area, U(t)= at exp(-bt(2)) (where a and b are non-universal, material-dependent constants), that the scaling exponents can be different from the MFT values. Normalizing U by A(m) and t by t(m) (the time belonging to the A(m): rise time), we obtain tm similar to A(m)(1-phi) (the MFT values can be obtained only if phi would be zero). Here, phi is expected to be material-independent and to be the same for the same mechanism. Using experimental results on martensitic transformations in two different shape-memory single-crystals, phi = 0.8 +/- 0.1 was obtained (phi is the same for both alloys). Thus, dividing U by A(m) as well as t by A(m)(1-phi) (similar to t(m)) leads to the same common, normalized temporal shape for different, fixed values of S. This normalization can also be used in general for other experimental results (not only for acoustic emission), which provide information about jerky noises in materials. LA - English DB - MTMT ER - TY - JOUR AU - Daróczi, Lajos AU - Elrasasi, T.Y. AU - Arjmandabasi, T. AU - Tóth, László Zoltán AU - Veres, B. AU - Beke, Dezső TI - Change of acoustic emission characteristics during temperature induced transition from twinning to dislocation slip under compression in polycrystalline sn JF - MATERIALS J2 - MATERIALS VL - 15 PY - 2022 IS - 1 SN - 1996-1944 DO - 10.3390/ma15010224 UR - https://m2.mtmt.hu/api/publication/32602494 ID - 32602494 N1 - Department of Solid State Physics, University of Debrecen, P.O. Box 400, Debrecen, H-4002, Hungary Department of Physics, Faculty of Science, Benha University, Benha, 13518, Egypt Export Date: 20 January 2022 Correspondence Address: Beke, D.L.; Department of Solid State Physics, P.O. Box 400, Hungary; email: dbeke@science.unideb.hu LA - English DB - MTMT ER - TY - JOUR AU - Bronstein, Emil AU - Tóth, László Zoltán AU - Daróczi, Lajos AU - Beke, Dezső AU - Talmon, Ronen AU - Shilo, Doron TI - Tracking Twin Boundary Jerky Motion at Nanometer and Microsecond Scales JF - ADVANCED FUNCTIONAL MATERIALS J2 - ADV FUNCT MATER VL - Epub PY - 2021 SP - 1 EP - 11 PG - 11 SN - 1616-301X DO - 10.1002/adfm.202106573 UR - https://m2.mtmt.hu/api/publication/32289901 ID - 32289901 N1 - 322157 LA - English DB - MTMT ER - TY - JOUR AU - Hajdu, Péter AU - Lampé, István AU - Rácz, Richárd Péter AU - Biri, Sándor AU - Csík, Attila AU - Tóth, Ferenc AU - Szalóki, Melinda AU - Hegedűs, V AU - Dombrádi, Zsuzsanna Rita AU - Varga, István AU - Csarnovics, István AU - Kökényesi, Sándor Jenő AU - Beke, Dezső AU - Hegedűs, Csaba TI - Optimized Size and Distribution of Silver Nanoparticles on the Surface of Titanium Implant Regarding Cell Viability JF - APPLIED SCIENCES-BASEL J2 - APPL SCI-BASEL VL - 10 PY - 2020 IS - 20 SN - 2076-3417 DO - 10.3390/app10207063 UR - https://m2.mtmt.hu/api/publication/31625545 ID - 31625545 N1 - Institute for Nuclear Research (ATOMKI), Bem tér 18/c, Debrecen, H-4026, Hungary Faculty of Science and Technology Institute of Physics, University of Debrecen, Bem tér 18/a, Debrecen, H-4026, Hungary Doctoral School of Physics, University of Debrecen, Egyetem sqr. 1., Debrecen, H-4032, Hungary Department of Biomaterials and Prosthetic Dentistry, Faculty of Dentistry, University of Debrecen, Nagyerdei Rd. 98, Debrecen, H-4032, Hungary Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Nagyerdei Rd. 98., Debrecen, H-4032, Hungary Department of Periodontology, Faculty of Dentistry, University of Debrecen, Nagyerdei Rd. 98, Debrecen, H-4032, Hungary Department of Solid State Physics, University of Debrecen, Bem tér 18/b, Debrecen, H-4026, Hungary Export Date: 28 October 2020 Correspondence Address: Hegedűs, C.; Department of Biomaterials and Prosthetic Dentistry, Faculty of Dentistry, University of Debrecen, Nagyerdei Rd. 98, Hungary; email: hegedus.csaba.prof@dental.unideb.hu Institute for Nuclear Research (ATOMKI), Bem tér 18/c, Debrecen, H-4026, Hungary Faculty of Science and Technology Institute of Physics, University of Debrecen, Bem tér 18/a, Debrecen, H-4026, Hungary Doctoral School of Physics, University of Debrecen, Egyetem sqr. 1., Debrecen, H-4032, Hungary Department of Biomaterials and Prosthetic Dentistry, Faculty of Dentistry, University of Debrecen, Nagyerdei Rd. 98, Debrecen, H-4032, Hungary Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Nagyerdei Rd. 98., Debrecen, H-4032, Hungary Department of Periodontology, Faculty of Dentistry, University of Debrecen, Nagyerdei Rd. 98, Debrecen, H-4032, Hungary Department of Solid State Physics, University of Debrecen, Bem tér 18/b, Debrecen, H-4026, Hungary Export Date: 26 January 2021 Correspondence Address: Hegedűs, C.; Department of Biomaterials and Prosthetic Dentistry, Nagyerdei Rd. 98, Hungary; email: hegedus.csaba.prof@dental.unideb.hu Institute for Nuclear Research (ATOMKI), Bem tér 18/c, Debrecen, H-4026, Hungary Faculty of Science and Technology Institute of Physics, University of Debrecen, Bem tér 18/a, Debrecen, H-4026, Hungary Doctoral School of Physics, University of Debrecen, Egyetem sqr. 1., Debrecen, H-4032, Hungary Department of Biomaterials and Prosthetic Dentistry, Faculty of Dentistry, University of Debrecen, Nagyerdei Rd. 98, Debrecen, H-4032, Hungary Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Nagyerdei Rd. 98., Debrecen, H-4032, Hungary Department of Periodontology, Faculty of Dentistry, University of Debrecen, Nagyerdei Rd. 98, Debrecen, H-4032, Hungary Department of Solid State Physics, University of Debrecen, Bem tér 18/b, Debrecen, H-4026, Hungary Export Date: 28 May 2021 Correspondence Address: Hegedűs, C.; Department of Biomaterials and Prosthetic Dentistry, Nagyerdei Rd. 98, Hungary; email: hegedus.csaba.prof@dental.unideb.hu LA - English DB - MTMT ER - TY - JOUR AU - Makushko, P.V. AU - Shamis, M.N. AU - Schmidt, N.Y. AU - Kotenko, I.E. AU - Gulyás, Szilvia AU - Katona, Gábor AU - Verbytska, T.I. AU - Beke, Dezső AU - Albrecht, M. AU - Makogon, I.M. TI - Formation of ordered L10-FePt phase in FePt–Ag thin films JF - APPLIED NANOSCIENCE J2 - APPL NANOSCI VL - 10 PY - 2020 IS - 12 SP - 4809 EP - 4816 PG - 8 SN - 2190-5509 DO - 10.1007/s13204-020-01552-2 UR - https://m2.mtmt.hu/api/publication/31609701 ID - 31609701 AB - In this work, the influence of an Ag layer, which is located at different positions of the layer stack (top, intermediate, bottom), on the structural and magnetic properties of orderedL1(0)phase in Fe(50)Pt(50)films was investigated. It was found that the position of an additional Ag layer affects the stress state of the as-deposited FePt films. Mechanical stress is induced during deposition and post-annealing process due to the difference in thermal expansion coefficients and lattice mismatch of FePt, Ag, and substrate. The initial stress state affects the ordering process during subsequent heat treatment. The higher level of initial compressive stress (- 7.8 GPa) in FePt/Ag/FePt films results inL1(0)phase formation at a temperature of 700 degrees C which is about 100 degrees C lower than in films with Ag bottom (- 3.6 GPa) and top (+ 0.86 GPa) layers. A more pronounced (001) oriented growth of theL1(0)phase was observed in stacks with Ag top layer as compared to Ag bottom and intermediate layers. The highest values of coercivity were obtained for films with Ag intermediate and bottom layers, which is due to the distribution of Ag along FePt grain boundaries that result in strong exchange decoupling of FePt grains. Furthermore, the formation of the orderedL1(0)phase at comparatively low temperatures of about 370 degrees C was observed in a free-standing FePt/Ag (30 nm)/FePt film. LA - English DB - MTMT ER -