Article
Chemistry, Physical
Christian Gawert, Ruediger Baehr
Summary: A new procedure for automatic measurement of SDAS from microscopic images is introduced and successfully applied to two hypoeutectic aluminum cast alloys, showing good agreement between automated and manually measured values. A decrease in computation time allowed for an increase in measurement density for characterizing microstructures.
Article
Chemistry, Physical
Mrowka-Nowotnik Grazyna, Kamil Gancarczyk, Andrzej Nowotnik, Kamil Dychton, Grzegorz Boczkal
Summary: The study focuses on the possibility of manufacturing standardized alloy 2017A through continuous casting using commercial and post-production scrap. The alloy in its as-cast state exhibited various intermetallic phases which were dissolved or precipitated during solution heat treatment and aging, resulting in improved mechanical properties. The highest strength properties were achieved after specific heat treatment processes, showing promise for recycled scrap alloy with relatively high mechanical properties.
Article
Nanoscience & Nanotechnology
Massoud Emamy, Hamed Mirzadeh, Mohammadbaqer Ra'ayatpour, Hooman Abedi
Summary: The microstructural development and mechanical properties of newly developed Mg-5Ni-xAl (x = 2.5, 5, and 7.5 wt%) alloys were investigated. The results showed that increasing the Al content and hot extrusion treatment significantly improved the mechanical properties, resulting in grain refinement and phase dispersion, leading to the best tensile properties.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Metallurgy & Metallurgical Engineering
Mathias Silmbroth, Salar Bozorgi, Salar Bozorgi
Summary: The development of AlZnMg(Cu) alloys was carried out using thermodynamic simulations and experimental tests, predicting solidification processes and phase compositions. Alloys with higher contents of alloying elements like iron and silicon, such as AlZn4Mg3Cu(Fe) and AlZn5Mg4Cu, were successfully processed with a cold-chamber die casting machine. An energy- and time-saving optimization of material properties was achieved through a modified heat treatment method (T6*) with a total time of only 12 h.
INTERNATIONAL JOURNAL OF METALCASTING
(2021)
Article
Materials Science, Multidisciplinary
T. K. Akopyan, P. K. Shurkin, N. V. Letyagin, F. O. Milovich, A. S. Fortuna, A. N. Koshmin
Summary: The experimental studies showed that adding trace amounts of tin refines the Al2Cu phase in an Al-Cu based alloy, resulting in a significant increase in peak hardness by about 20% and a reduction in aging time to peak hardness from 12 hours to 2 hours at 175 degrees Celsius. This increase in hardness is attributed to the formation of finer theta-phase precipitates with high number density, as observed in TEM and APT analyses.
Article
Materials Science, Multidisciplinary
Feng Wang, Yu-Lung Chiu, Dmitry Eskin, Wenjia Du, Paul R. Shearing
Summary: The study found that the addition of vanadium can cause grain refinement of cast commercial purity aluminium, mainly due to the high nucleation potency and sufficient growth restriction effect of Al10V particles. In addition, the relatively large size of Al10V particles helps to promote the nucleation of aluminium grains.
MATERIALS CHARACTERIZATION
(2021)
Article
Nanoscience & Nanotechnology
P. Hidalgo-Manrique, S. Cao, H. R. Shercliff, R. D. Hunt, J. D. Robson
Summary: In the process development trial, two identical automotive parts were formed from commercial 6082 Al alloy using Hot Form Quench (HFQ). The study compared microstructures and hardness at different locations in the parts, finding that the HFQ process did not result in a loss of hardening potential and that microstructures converged after artificial aging. Tensile tests showed that ductility and failure mechanism were insensitive to small differences in grain boundary microstructure observed in the HFQ component.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
E. Scharifi, U. Savaci, Z. B. Kavaklioglu, U. Weidig, S. Turan, K. Steinhoff
Summary: The research found that the tool temperature significantly affects the strength and microstructure of AA7075 aluminum alloy, causing fundamental changes in microstructure and strain hardening behavior when exceeding a certain temperature limit. At tool temperatures below 200℃, there is only a slight decrease in tensile strength, while above 200℃, there is a significant drop in tensile strength and an increase in the initial strain hardening rate.
MATERIALS CHARACTERIZATION
(2021)
Article
Materials Science, Multidisciplinary
Maria V. Glavatskikh, Ruslan Yu. Barkov, Leonid E. Gorlov, Maxim G. Khomutov, Andrey V. Pozdniakov
Summary: The main weaknesses of commercial high-strength Al-Zn-Mg-Cu-based alloys are the low casting properties, corrosion and heat resistance. Alloys with a Zn/Mg ratio of 1 and a Cu/Y(Er) atomic ratio of 4 were developed to improve the casting properties and heat resistance of Al-Zn-Mg-Cu-based alloys. The microstructure, phase transformation, and tensile properties of the novel alloys were investigated.
Article
Chemistry, Physical
Adam Debski, Sylwia Terlicka, Anna Sypien, Wladyslaw Gasior, Magda Peska, Marek Polanski
Summary: This study investigates the hydrogen sorption properties of casted Ag-Mg alloys and finds that samples with high magnesium content readily absorb significant amounts of hydrogen, while no hydrogen absorption is observed for samples with high silver concentrations.
Article
Nanoscience & Nanotechnology
Shengze Yin, Peyman Saidi, Andrew Howells, Mark Gallerneault, Vahid Fallah
Summary: A comprehensive and experimentally verified yield strength model of AA6005 Al-Mg-Si sheets rapidly solidified via a novel Thin Strip (TS) casting route is developed. The TSH conditions result in higher strength and higher precipitate volume fractions, achieving peak aging at 180℃ after only 30 minutes to 1 hour.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
F. Theska, R. Buerstmayr, H. Liu, M. Lison-Pick, S. R. Street, S. Primig
Summary: This study investigates the influence of microalloying elements B and Zr on the hot workability and grain boundary decoration of Rene 41 superalloys. Two different variants of Rene 41 with varying B and Zr concentrations were manufactured and analyzed using correlative microscopy and atom probe microscopy. The results provide insights into the precipitation of gamma' and M2B at grain boundaries and the interfacial excess close to prone-to-cracking grain boundaries. Optimized solute concentrations are proposed based on the findings, enabling the next iteration of superalloy design using microalloying.
MATERIALS CHARACTERIZATION
(2022)
Article
Materials Science, Multidisciplinary
Rahul Gope, Sukla Mondol, Sourav Ganguly, Animesh Mandal
Summary: The microstructure and tensile properties of Al-12Ce, Al-12Ce-4Si, and Al-12Ce-4Si-0.4Mg alloys (wt-%), fabricated by suction-casting (SC) and gravity-casting (GC), were compared. The SC alloys showed finer grains and more precipitates compared to the GC alloys. Addition of Si and Mg in Al-12Ce alloy improved the hardness significantly. Incorporating 4Si and 0.4Mg enhanced the yield and tensile stress but reduced ductility in the SC alloys. The SC Al-12Ce-4Si-0.4Mg alloy exhibited the best hardness and tensile strength. The fracture behavior of SC Al-12Ce alloy changed from quasi-cleavage to complete cleavage fracture following the addition of 4Si and 0.4Mg.
MATERIALS SCIENCE AND TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Milad Maleki, Fatemeh Jamei, Massoud Emamy, Hamed Mirzadeh
Summary: The effects of nickel addition to magnesium in the hypoeutectic range were examined in the as-cast and extruded conditions. The results showed that at low nickel content (5 wt-%), grain-boundary eutectics were present in the refined alpha-Mg matrix, while at high nickel content (15 wt-%), the eutectic constituent became the matrix of the alloy with the appearance of alpha-Mg rosettes. The addition of nickel up to 15 wt-% significantly improved the strength-ductility balance. Moreover, the formation of long Mg2Ni particles at the boundaries of eutectic colonies was explained based on the cooling curve thermal analysis results. Additionally, the remarkable grain refinement through dynamic recrystallisation (DRX) and fragmentation/dispersion of intermetallic particles during hot extrusion resulted in improved tensile strength, ductility, and toughness.
MATERIALS SCIENCE AND TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Felix Theska, Wilson F. F. Tse, Bernd Schulz, Richard Buerstmayr, Steven R. R. Street, Michael Lison-Pick, Sophie Primig
Summary: Cast and wrought Ni-based superalloys are preferred materials for harsh high-temperature environments, and their compositional complexity requires advanced processing techniques. Microalloying additions of B, C, and Zr can improve high-temperature strength and creep resistance, but excessive additions are detrimental. The role of grain boundary segregation and precipitation in mechanical properties is well researched, but co-precipitation near grain boundaries needs further exploration. Understanding the processing-microstructure-properties relationships in advanced Ni-based superalloys is crucial.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Chemistry, Physical
Luojia Zhang, Evgeny Zhuravlev, Jun Yi, Qijie Zhai, Christoph Schick, Yulai Gao, Bingge Zhao
Summary: Crystal nucleation is a crucial step in the crystallization of metallic glasses. However, the nucleation kinetics can deviate from the classical nucleation theory as the undercooling increases. This study examines the nucleation kinetics in glass and undercooled melt using nanocalorimetry. By varying the cooling rate, the processes of crystallization, homogeneous nucleation, and heterogeneous nucleation are distinguished. The critical cooling rates for suppressing crystallization and nucleation are estimated, and a well-identified amorphous phase is produced for nucleation studies. The underlying kinetic mechanism is revealed through the analysis of crystallization heat and overall heat using the Johnson-Mehl-Avrami method.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Ruslan A. Andrianov, Juern W. P. Schmelzer, Rene Androsch, Timur A. Mukhametzyanov, Christoph Schick
Summary: The specific features of crystal nucleation have a significant impact on the morphology of the crystalline material. Due to their small size and stochastic nature, it is usually difficult to observe the development of nuclei directly. However, an experimental approach using fast scanning calorimetry has been developed to determine the specific features of the cluster size distribution. This approach allows for estimating the time evolution of the largest detectable clusters in the distribution and determining their radial growth rate.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Materials Science, Ceramics
Semen E. Lapuk, Marat A. Ziganshin, Radik A. Larionov, Timur A. Mukhametzyanov, Christoph Schick, Alexander V. Gerasimov
Summary: Robust determination of parameters governing the stability of amorphous drugs is crucial in modern pharmaceutics. The kinetic stability of these systems greatly impacts their practical applications. This study determined the critical cooling rates and kinetic parameters of cold crystallization for four slowly crystallizing sulfonamides. The Nakamura crystallization model demonstrated good prognostic ability by determining the stability time profile of drug systems prone to crystallization from non-isothermal thermokinetic data.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2023)
Article
Materials Science, Multidisciplinary
Seyed Vahid Sajadifar, Philipp Krooss, Marcel Krochmal, Thomas Wegener, Akbar Heidarzadeh, Hannes Froeck, Janez Zavasnik, Olaf Kessler, Thomas Niendorf
Summary: This study presents the effects of aging under superimposed external stress on the fatigue performance and microstructural evolution of a high-strength aluminum alloy (EN AW-7075). The combination of heat treatment and external stress, known as stress aging, accelerates the precipitation kinetics and promotes the formation and growth of strengthening precipitates. The stress aging process also reduces the dimensions of precipitate-free zones near grain boundaries. Furthermore, stress aging enhances the monotonic mechanical properties of EN AW-7075 without degrading the cyclic performance in the low-cycle fatigue regime.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Thermodynamics
Aleksey V. Buzyurov, Ruslan N. Nagrimanov, Timur A. Mukhametzyanov, Marat A. Ziganshin, Boris N. Solomonov, Christoph Schick
Summary: The vapor pressures and enthalpies of sublimation/vaporization/fusion were measured for acetanilide and eight derivatives. The obtained vapor pressures resolved contradictions in the literature and confirmed previous values for certain compounds. Sublimation and vaporization enthalpies were determined and mostly agreed with literature values. Fusion enthalpies of certain compounds were determined using different methods and showed consistency with literature values.
JOURNAL OF CHEMICAL AND ENGINEERING DATA
(2023)
Article
Polymer Science
Akihiko Toda, Yoshitomo Furushima, Christoph Schick
Summary: In this study, the isothermal crystallization kinetics of poly(butylene terephthalate) at low temperatures near the glass transition was investigated using chip-sensor fast scanning calorimetry. The Avrami analysis showed that the Avrami index decreased from 4 to less than 2 in the low-temperature peak of the crystallization rate, resulting in significantly low crystallinity near the glass-transition temperature. This phenomenon was attributed to the inhibition of crystal growth by the rigid amorphous fraction (RAF) that is constrained by crystals, as proposed by Schawe for other crystalline polymers. The transformation of the mobile amorphous fraction (MAF) into RAF with the progress of crystallization was confirmed near the glass-transition temperature, leading to the rigidification of all amorphous fractions.
Article
Medicine, Research & Experimental
Semen E. Lapuk, Timur A. Mukhametzyanov, Christoph Schick, Alexander Gerasimov
Summary: The application of drugs in the amorphous state is being actively researched in pharmaceutical science to enhance their bioavailability. In this study, the kinetic stability and glass-forming ability of thermally labile quinolone antibiotics were investigated using fast scanning calorimetry. The critical cooling rates for preventing crystallization of oxolinic acid, pipemidic acid, and sparfloxacin were determined to be 10,000, 40, and 80 K·s-1 respectively, indicating their strong glass-forming ability. The Nakamura model was found suitable for describing the crystallization process of the amorphous forms of the quinolone antibiotics using a combination of nonisothermal and isothermal kinetic approaches.
MOLECULAR PHARMACEUTICS
(2023)
Article
Chemistry, Multidisciplinary
Alexander Minakov, Christoph Schick
Summary: This article studies the influence of various mesoscopic effects on interfacial thermal conductance (ITC) during fast melting processes and the contributions to ITC in pre-melting and melting processes of metal microparticles. The gained knowledge is useful for understanding and optimizing technological processes involving fast melting, such as laser additive manufacturing.
APPLIED SCIENCES-BASEL
(2023)
Article
Polymer Science
Akihiko Toda, Yoshitomo Furushima, Christoph Schick
Summary: The relationship between the changes in the crystallization kinetics and the crystal domains of poly(butylene terephthalate) was investigated under isothermal conditions. The Avrami exponent n characterizing the nucleation and growth kinetics of the crystal domains exhibited a continuous change within the target temperature range, indicating a change in the nucleation mode for spherical domains. The morphology of the crystal domains responsible for this change was identified, with a continuous change in the size of spherulites observed. The formation of 10 nm scale granular nodules with high nuclei density at low temperatures was also observed.
Article
Materials Science, Multidisciplinary
Robert Kahlenberg, Georg Falkinger, Benjamin Milkereit, Ernst Kozeschnik
Summary: This paper proposes an efficient model for handling heterogeneous nucleation site energy variations and studies their impact on solute nucleation behavior. The model has advantages compared to previous simulations, especially for slow cooling rates.
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
(2023)
Article
Polymer Science
Rene Androsch, Katalee Jariyavidyanont, Andreas Janke, Christoph Schick
Summary: In this study, the melt-crystallization process of PBS under different melt-supercooling conditions was analyzed using X-ray scattering techniques, microscopy, and fast scanning chip calorimetry. It was found that lamellar thickening is not the main mechanism of isothermal secondary crystallization, and low-temperature crystallization leads to the presence of crystal defects.
Article
Chemistry, Physical
Yeong Zen Chua, Reiner Zorn, Juern W. P. Schmelzer, Christoph Schick, Olaf Holderer, Michaela Zamponi
Summary: To understand the properties of glass-forming liquids, the concept of cooperativity length is widely used. Experimental methods of determining this quantity are crucial for the understanding of both thermodynamic and kinetic properties. In this study, the cooperative length and cooperativity number were determined using AC calorimetry and QENS, and the results depended on whether temperature fluctuations were considered. The comparison between the two methods indicated that considering temperature fluctuations is important, and the cooperativity length can be derived from thermodynamic considerations.
ACS PHYSICAL CHEMISTRY AU
(2023)
Article
Chemistry, Physical
Semen Lapuk, Marina Ponomareva, Marat Ziganshin, Radik Larionov, Timur Mukhametzyanov, Christoph Schick, Ivan Lounev, Alexander Gerasimov
Summary: In this study, the glass transition of the biocompatible polymer polyvinylpyrrolidone was investigated using differential scanning calorimetry, fast scanning calorimetry, and broadband dielectric spectroscopy. The dependence of the difference in isobaric specific heat capacities between the liquid and glass on the dynamic glass transition temperature, volume, and number of particles in the cooperatively rearranging regions was determined. A linear relationship between the shift factor from the Frenkel-Kobeko-Reiner equation and the molecular mass of polyvinylpyrrolidone was established. These findings contribute to the selection of optimal excipients for the development of solid dispersions based on amorphous polymers.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Thermodynamics
Timur A. Mukhametzyanov, Ruslan A. Andrianov, Dmitrii N. Bolmatenkov, Mikhail I. Yagofarov, Boris N. Solomonov, Christoph Schick
Summary: The nucleation and crystallization of the rapidly crystallizing organic compound benzocaine show different behaviors under different supercooling conditions, and the temperature transition of nucleation and crystallization is sharp and sample-dependent.
THERMOCHIMICA ACTA
(2023)
Article
Materials Science, Multidisciplinary
Matteo Villa, Flemming B. Grumsen, Frank Niessen, Thomas Dahmen, Lingfei Cao, Michael Reich, Olaf Kessler, Xiaoxu Huang, Marcel A. J. Somers
Summary: The present investigation studied the effects of austenite aging on precipitation hardening martensitic stainless steel. It was found that austenite aging promotes the formation of copper clusters and particles, affects the kinetics and substructure of martensite formation, and significantly strengthens the material. The contribution of precipitates to the strength of martensite was interpreted using the Russell-Brown model.