Article
Materials Science, Multidisciplinary
L. J. Liu, S. Y. Lu, Q. Y. Qin, L. Yang, J. F. Li
Summary: This study investigated the solidification process of Ni75B25 alloy under different undercooling conditions and identified the formation and transformation mechanism of the Ni23B6 phase. It was found that the alloy solidifies completely into Ni3B phase when the undercooling is less than 240K. At larger undercooling, the metastable Ni23B6 phase primarily forms in the melt but then decomposes into alpha-Ni and Ni3B through a eutectoid reaction. The delay time between the two temperature recalescence events affects the amount of residual liquid and the recalescence temperature.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2022)
Article
Metallurgy & Metallurgical Engineering
Wei LI, Xiu-xun Wei, Jin-fu LI
Summary: The relationship between anomalous eutectic and the remelting of the primary phase in Ni-19.6at.%P eutectic alloy was investigated. Fully regular eutectic structures were obtained when thin samples were solidified over a range of undercoolings with temperature recalescence depressed. Rapidly heating the thin samples to certain temperatures between the nucleation and eutectic temperatures resulted in anomalous eutectic structure. It was found that the volume fraction of anomalous eutectic increased with increasing target temperature, with alpha-Ni particulates randomly oriented and beta-Ni3P phase well oriented in the anomalous eutectic formed upon heating.
TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
(2023)
Article
Chemistry, Physical
Yuhao Wu, Baorong Zhu, Jingwen Su, Zhiming Gao, Xing Zhao
Summary: The influences of cooling style on the kinetics of metastable phase separation in undercooled liquid Fe35Cu65 alloy were systematically investigated. Results showed that the phase separation time increased linearly with the undercooling, and the morphology changed as well. Under forced cooling condition, a larger critical undercooling was required to form the core-shell separation morphology, and the phase separation time was shorter. The theoretical analyses were confirmed by numerical simulations and experiments.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Fan Zhang, Jianbao Zhang, Xinlei Lu, Ke Hua, Yuhong Zhao, Haifeng Wang
Summary: Rapid solidification in undercooled Ni-18.7 at.%Sn eutectic melts was captured in real-time using a high-speed high-resolution camera and characterized using electron backscattering diffraction. The crystallographic orientation relations (ORs) between HCP-Ni 3 Sn (alpha-Ni) subsets were analyzed, revealing the independent presence of HCP-Ni 3 Sn twins regardless of undercooling. The formation mechanism of HCP-Ni 3 Sn twins was explored by considering twinning and allotropy transformation, and a reversed OR transition analysis was conducted.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Physical
L. J. Liu, J. F. Li
Summary: The effect of Co/Ni atomic ratio on the formation and stability of metastable phases in Co-Ni-B alloys was investigated. It was found that substitution of Co by Ni reduces the possibility of forming the metastable M2B phase and completely eliminates it from the solidification process at certain undercoolings. All investigated Co-Ni-B alloys solidify into a single metastable M23B6 phase at large undercoolings. However, the stability of the M23B6 phase decreases with increasing Ni content, leading to its decomposition into α-M and M3B phases during the post-solidification cooling process when x ≥ 0.75.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Peng Peng, Anqiao Zhang, Jinmian Yue, Shengyuan Li, Wanchao Zheng, Li Lu
Summary: This study investigated the solidification of Sn-Ni peritectic alloys and found that the peritectic reaction rate is smaller than previous reports, with peritectic phase mainly growing through direct precipitation from the melt. Step growth of both Ni3Sn2 and Ni3Sn4 phases was observed, with the step thicknesses of both phases decreasing as solidification proceeds. Additionally, the normal growth velocity of Ni3Sn4 phase was found to increase with increasing cooling rate.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Carolina Kreischer, Thomas Volkmann
Summary: The study investigates the solidification process of undercooled Fe-Co alloy melts by observing the delay time between the formation of metastable and stable phases, which decreases significantly with increasing undercooling. The results suggest that the delay time is influenced by both nucleation kinetics and the growth velocity and morphology of the primary metastable phase, which are dependent on undercooling.
Article
Chemistry, Physical
Naifang Zhang, Wenquan Lu, Zongye Ding, Qiaodan Hu, Jianguo Li
Summary: The growth pattern and 3D morphology of primary Al3Ni in directionally solidified Al-16wt%Ni alloys at different pulling rates were investigated by synchrotron to-mography. The Al3Ni crystals transformed from faceted prism to non-faceted dendrites with V-shaped faceted arm ends as the cooling rate increased. Faceted Al3Ni grew along [100] direction bounded by {011} facets, while the growth direction of non-faceted Al3Ni dendrites changed from [011] to [010]. The weakening of faceted growth characteristics in the slow cooled sample was mainly attributed to the decrease of entropy of fusion caused by low Ni content in the liquid. A multi-layer atom model was established to describe and reveal the formation mechanism of faceted/non-faceted mixed structure at high cooling rate.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
X. L. Zhao, J. Chang, P. X. Yan, M. X. Li, B. Wei
Summary: In this study, liquid Ni-47.7% Mo alloy was undercooled and solidified under microgravity conditions to investigate the correlation between microhardness enhancement and eutectic growth mechanism. The results showed that with increased alloy undercooling, the eutectic interphase spacings decreased, leading to significant structural refinement and a noticeable rise in Vickers hardness.
Article
Materials Science, Multidisciplinary
R. L. Xiao, Y. Ruan, M. J. Lin, L. Hu, B. Wei
Summary: In this study, a Ti-Ni-Al alloy comprised of metastable equiaxed dendrites and interdendritic Ti2Ni phase was prepared using electrostatic levitation plus quenching. The alloy showed a remarkable improvement in hardness compared to the sample processed through DTA. By employing double Cs corrector transmission electron microscope characterization, it was found that coherent solute clusters and semi-coherent nano-distortions formed within the metastable dendrites, while α Ti nanoprecipitates generated inside the interdendritic Ti2Ni phase matrix. These dispersive metastable nanostructures and the novel biphase boundary contributed to the pinning of dislocations. The harmonic cooperation of precipitation strengthening, solution strengthening, and fine-grained strengthening were achieved to enhance the alloy.
Review
Metallurgy & Metallurgical Engineering
Wen-quan Lu, Nai-fang Zhang, Zong-ye Ding, Qiao-dan Hu, Jian-guo LI
Summary: The solidification process of metals is crucial for their final performance, and it is important to study this process using advanced in situ techniques. Synchrotron radiation X-ray imaging is a powerful technique that allows direct observation of the solidification process of metals. This article reviews the development of solidification apparatus and highlights recent progress in using synchrotron radiation X-ray imaging to study the solidification behavior of metals.
TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
(2022)
Article
Chemistry, Physical
Yukang An, Xiaolong Xu, Yongchao Hao, Ruifeng Dong, Hua Hou, Yuhong Zhao, Tao Gu, Hongfu Wang
Summary: The effect of Co addition on the solidification velocity, hardness, and refined structure transformation of undercooled Ni-Cu-Co alloys has been investigated. It is found that Co addition increases the solidification velocity and recalescence effect by increasing the number of solidified crystal nucleus and solute diffusion velocity. The improved solidification velocity and stress-induced deformation effect by Co addition lead to increased low-angle grain boundaries and decreased grain size, resulting in significantly improved hardness of the refined structure.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Yukang An, Xiaolong Xu, Yuhong Zhao, Ruopeng Lu, Ruifeng Dong, Zhanyong Zhao, Hua Hou
Summary: In this study, the relationship between critical undercooling ΔT* and nonequilibrium solidification velocity of single-phase alloys, as well as the mechanism of refined structure transformation, were fully investigated. The results showed that higher solidification velocity resulted in more solid phase production during recalescence, leading to greater stress accumulation and increased likelihood of grain refinement. Refined structures at high undercooling exhibited higher misorientation, Sigma(3) twin boundaries, and high-angle grain boundaries, indicating recrystallization in microstructures. Increasing ΔT led to rapid increase in accumulated stress and plastic strains during recalescence. However, when ΔT exceeded the critical undercooling ΔT*, the strain degree and hardness suddenly decreased, indicating the disappearance of accumulated stress and plastic strains due to the driving force of the system during the post-recalescence period and recrystallization in microstructures. The results fully demonstrated that stress-induced recrystallization caused the refined structure transformation at high undercooling.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Review
Metallurgy & Metallurgical Engineering
Guang Zeng, Shiqian Liu, Qinfen Gu, Zebang Zheng, Hideyuki Yasuda, Stuart D. McDonald, Kazuhiro Nogita
Summary: It is widely recognized that a fundamental understanding of phase transformation and microstructure control in Pb-free solder joints can accelerate the development of Pb-free solder alloys for next-generation electronics. Advanced characterization techniques, including synchrotron radiation, provide a comprehensive toolset for measuring the composition, crystallography, morphology, and properties of solder alloys. Research findings on the effects of micro-alloy additions on the microstructure and properties of Pb-free solder joints, particularly on intermetallic phases, have significant scientific and industrial implications for the design of new solder alloy compositions and the reliability of lead-free solder joints.
ACTA METALLURGICA SINICA-ENGLISH LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Domonkos Tolnai, Sarkis Gavras, Fabian Wilde, Jorg U. Hammel, Stefan Bruns
Summary: The directional solidification of an Elektron 21 magnesium alloy was investigated using in situ synchrotron radiation tomography. The growth of secondary dendrite arms and coarsening of existing dendrite arms were observed during the solidification process, with the contrast between rare-earth metals and Mg enabling quantitative analysis of changes in morphology.
ADVANCED ENGINEERING MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Daniel Wolf, Sebastian Schneider, Ulrich K. Rossler, Andras Kovacs, Marcus Schmidt, Rafal E. Dunin-Borkowski, Bernd Buechner, Bernd Rellinghaus, Axel Lubk
Summary: Holographic vector-field electron tomography quantitatively reconstructed the three-dimensional magnetic texture of Bloch skyrmion tubes in FeGe with sub-10-nanometre resolution, revealing complex three-dimensional modulations and fundamental principles of skyrmion formation.
NATURE NANOTECHNOLOGY
(2022)
Article
Physics, Multidisciplinary
Rui Lou, Alexander Fedorov, Qiangwei Yin, Andrii Kuibarov, Zhijun Tu, Chunsheng Gong, Eike F. Schwier, Bernd Buechner, Hechang Lei, Sergey Borisenko
Summary: The entanglement of charge density wave (CDW), superconductivity, and topologically nontrivial electronic structure has been discovered in the kagome metal AV3Sb5 (A = K, Rb, Cs) family recently. Using high-resolution angle-resolved photoemission spectroscopy, the electronic properties of CDW and superconductivity in CsV3Sb5 are studied. The spectra around K over line exhibit a peak-dip-hump structure associated with two separate branches of dispersion, indicating the isotropic CDW gap opening below EF. The presence of a superconducting gap on both the electron band around Gamma over line and the flat band around K suggests multiband superconductivity. Our results shed light on the controversial origin of the CDW and provide insights into the relationship between CDW and superconductivity.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Lorenzo Francesco Madeo, Patrizia Sarogni, Giuseppe Cirillo, Orazio Vittorio, Valerio Voliani, Manuela Curcio, Tyler Shai-Hee, Bernd Buechner, Michael Mertig, Silke Hampel
Summary: A hybrid hydrogel was developed by loading curcumin onto graphene oxide nanosheets and blending them into an alginate hydrogel. The resulting system showed improved stability and exhibited strong anticancer effects.
Article
Materials Science, Multidisciplinary
T. Klaproth, E. Mueller, C. Habenicht, B. Buechner, M. Knupfer, M. Roslova, A. Isaeva, T. Doert, A. Koitzsch
Summary: Transition metal trichlorides exhibit peculiar and versatile magnetic properties. This study reveals that transition metal substitution can modify the optical properties of the host without compromising its electronic structure. The findings highlight the potential of material engineering in trichlorides.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
Felix Talnack, Sebastian Hutsch, Michael Bretschneider, Yulia Krupskaya, Bernd Buechner, Marc Malfois, Mike Hambsch, Frank Ortmann, Stefan C. B. Mannsfeld
Summary: Polymorphism refers to the ability of many organic molecules to adopt different crystal structures without changing their chemical structure. It has been found to have an impact on the solid-state properties of organic materials, such as charge transport in organic semiconductors. In this study, a new polymorphic crystal structure of the p-type small molecule semiconductor C10-DNTT is presented. The transition between different crystal structures was observed during heating, and the thin-film crystal structure of both polymorphs was refined using optical microscopy and X-ray scattering measurements. The thermal expansion and anisotropic molecular interactions were further analyzed using density-functional theory calculations.
MOLECULAR SYSTEMS DESIGN & ENGINEERING
(2022)
Article
Chemistry, Multidisciplinary
Felix Hansen, Rico Fucke, Titouan Charvin, Samuel Froeschke, Daniel Wolf, Romain Giraud, Joseph Dufouleur, Nico Graessler, Bernd Buechner, Peer Schmidt, Silke Hampel
Summary: This study proposes a method for the synthesis of mixed crystals of bismuth and antimony tellurides, which belong to the V2VI3 material family. The ideal synthesis conditions were determined through thermodynamic calculations and optimization experiments. The synthesized nanosheets exhibit high crystallinity and quality, with a significantly reduced carrier density compared to the binary compounds.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Chemistry, Multidisciplinary
Bertold Rasche, Julius Brunner, Tim Schramm, Madhav Prasad Ghimire, Ulrike Nitzsche, Bernd Buchner, Romain Giraud, Manuel Richter, Joseph Dufouleur
Summary: This paper presents a method using atomic force microscopy to measure the cleavage energy of van der Waals materials and quasi-two-dimensional materials. The method is validated through experiments and can be used as a tool for manipulating exfoliated flakes, offering a new route for the fabrication of nanostructures.
Article
Physics, Multidisciplinary
Seung-Ho Baek, Yeahan Sur, Kee Hoon Kim, Matthias Vojta, Bernd Buechner
Summary: Single crystals of pristine and 6% Pd-intercalated 2H-TaSe2 were studied using Se-77 nuclear magnetic resonance. The Se-77 spectrum showed line narrowing upon Pd intercalation, indicating the presence of correlated local lattice distortions above the charge density wave (CDW) transition temperature. The Knight shift data suggested a partial Fermi surface gap opening in the incommensurate CDW transition. The spin dynamics study revealed a pseudogap behavior dominating the low-energy spin excitations, which gets stronger along with superconductivity in the Pd-6% sample.
NEW JOURNAL OF PHYSICS
(2022)
Article
Multidisciplinary Sciences
Shu-Jen Wang, Michel Panhans, Ilia Lashkov, Hans Kleemann, Federico Caglieris, David Becker-Koch, Joern Vahland, Erjuan Guo, Shiyu Huang, Yulia Krupskaya, Yana Vaynzof, Bernd Buechner, Frank Ortmann, Karl Leo
Summary: The charge and thermoelectric transport in modulation-doped large-area rubrene thin-film crystals with different crystal phases were investigated. The results showed that modulation doping, together with high-mobility crystalline organic semiconductor films, is a previously unexplored strategy for achieving high-performance organic thermoelectrics. Theoretical studies provided insight into the energy landscape of the heterostructures and its influence on qualitative trends of the Seebeck coefficient.
Article
Physics, Condensed Matter
G. A. Stewart, G. N. Iles, R. A. Mole, Z. Yamani
Summary: The inelastic neutron scattering spectra recorded in this study and elsewhere provide a useful set of crystal-field energy levels for the ground J = 6 term of Ho3+ in HoFeO3. The resolution of the low-energy, temperature-dependent pseudo-quadrupole ground state splitting and magnon peaks is consistent with the self-ordering of the Ho3+ sublattice at T (Ho) similar to 8-10 K and supports earlier electron spin resonance investigations of the Ho3+ magnon behaviour. Systematic analysis of the grouped singlet CF levels of Ho-3: HoFeO3, in conjunction with the CF Kramers doublet levels of the neighbouring Er3+: ErFeO3, has yielded possible sets of CF parameters for the two systems.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Chemistry, Physical
Gail N. Iles, Will P. Gates, Jose E. M. Pereira, Anton P. J. Stampfl, Laurence P. Aldridge, Heloisa N. Bordallo
Summary: The capacity of clay minerals to store water is important for various applications on Earth and potentially on Mars. The behavior of water within clay minerals remains poorly understood, particularly at subzero temperatures. This study utilized neutron spectroscopy and spectral analysis to investigate the interaction between water and clay minerals. The results provide insights into the mechanism of water ice bonding and separation within clay interlayers, as well as the differences in ice forms depending on hydration levels.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Astronomy & Astrophysics
Brett A. Carter, Gail N. Iles, Rekha Raju, Andoh M. Afful, Ronald Maj, Tam Dao, Michael Terkildsen, Vasily Lobzin, Zahra Bouya, Murray Parkinson, Samantha Le May, Suelynn Choy, Pawel Hordyniec, Barbara Hordyniec, Julie Currie, Tamitha Skov, Ian D. Peake
Summary: Space weather plays a crucial role in the operation of various technological systems and applications. To equip students with the knowledge of how space weather affects their activities, RMIT University developed a Space Weather Prediction Laboratory. The lab provides an introduction to the near-Earth space environment and offers hands-on training in data analysis and communication.
JOURNAL OF SPACE WEATHER AND SPACE CLIMATE
(2022)
Article
Materials Science, Multidisciplinary
A. S. Sukhanov, Y. V. Tymoshenko, A. A. Kulbakov, A. S. Cameron, V. Kocsis, H. C. Walker, A. Ivanov, J. T. Park, V. Pomjakushin, S. E. Nikitin, I. V. Morozov, I. O. Chernyavskii, S. Aswartham, A. U. B. Wolter, A. Yaresko, B. Buechner, D. S. Inosov
Summary: FeP is a special material with complex noncollinear spin order. By measuring the spin-excitation spectra, we found that the magnons in FeP have strong anisotropic dispersions. The dominant antiferromagnetic interactions between rigid ferromagnetic spin chains drive the magnetic frustration in FeP.
Article
Materials Science, Multidisciplinary
Vilmos Kocsis, David A. S. Kaib, Kira Riedl, Sebastian Gass, Paula Lampen-Kelley, David G. Mandrus, Stephen E. Nagler, Nicolas Perez, Kornelius Nielsch, Bernd Buechner, Anja U. B. Wolter, Roser Valenti
Summary: In this combined theoretical and experimental research, the anisotropic magnetic and magnetoelastic properties of the Kitaev material alpha-RuCl3 were investigated. Unusually large magnetostriction anisotropy and non-symmetric magnetic anisotropy were observed, and their origins were explained based on the relative orientation of the magnetization with respect to the crystal structure.
Article
Materials Science, Multidisciplinary
F. Bougamha, S. Selter, Y. Shemerliuk, S. Aswartham, A. Benali, B. Buechner, H-J Grafe, A. P. Dioguardi
Summary: We report the anomalous breakdown in the scaling of the microscopic magnetic susceptibility with the bulk magnetic susceptibility in Mn2P2S6. NMR spectra provide evidence for domain rotation and spin-flop transition in the magnetic state. A spin-flop-induced splitting of the NMR spectra is observed in Ni2P2S6.
