Article
Crystallography
Yuehui Lu, Chuandong Wu, Hao Wu, Jiamin Wang, Yin Su, Zhanghua Gan, Jing Liu
Summary: In this study, the influence of annealing time on the microstructure and mechanical properties of Al-14.5Si alloys solidified under a super-gravity field was investigated. It was found that the coarsening of metastable eutectic Si and formation of precipitated Si occurred at the early stage of annealing. A slight increase in yield strength and tensile strength was observed in the sample annealed for 0.25 h, which was attributed to the formation of precipitated Si with limited size during the early stage of annealing. The intensified diffusion of Si atoms during annealing led to the coarsening and coalescence of the eutectic Si, as well as the coarsening of precipitated Si with further extension of the annealing time.
Article
Materials Science, Multidisciplinary
Lili Zhang, Zong-wei Ji, Jiuzhou Zhao, Jie He, Hongxiang Jiang
Summary: This study investigated the factors affecting eutectic Si modification in Al-Si hypoeutectic alloy with the addition of Na, Sr, Eu and Yb, and found that the modification effect is determined by element concentration in eutectic Si, solubility of modifying element M in alpha-Al, and interaction energy parameter of Al (or Si) and modifying element. A good modification is achieved by M of limited solubility in alpha-Al and a moderate interaction energy parameter of Si (or Al) and M. The results were verified by previous experimental results, and the effect of cooling rate on modification was also discussed.
Article
Chemistry, Physical
Cheng Gu, Michael P. Moodispaw, Alan A. Luo
Summary: The morphology of eutectic silicon in the solidification microstructure plays a critical role in the performance of Al-Si-based alloys. This study developed a three-dimensional cellular automaton model to simulate the transformation of eutectic (alpha-Al + Si) in multi-dendrite domains, providing a comprehensive simulation of the solidification process of Al-Si based alloys. The results were validated experimentally and showed good agreement with observations and calculations. This model has potential applications in predicting and optimizing the solidification microstructure, including eutectic transformation in processes such as casting, welding, and additive manufacturing.
NPJ COMPUTATIONAL MATERIALS
(2022)
Article
Chemistry, Physical
Mingshan Zhang, Keli Liu, Bing Wang, Tingting Liang, Jiaqiang Han, Junsheng Wang
Summary: The mechanical performance of Al-Si-Mg cast alloys is highly dependent on the pore size and morphology of eutectic Si. The addition of alloying elements can have an impact on the growth and morphology of eutectic Si.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Mengdan Hu, Taotao Wang, Hui Fang, Mingfang Zhu
Summary: A 2-D multi-component and multi-phase cellular automaton model coupled with the Calphad method and finite difference method was proposed to simulate gas pore formation and microstructures in the solidification process of hypoeutectic Al-Si-Mg alloys. The model can reproduce interactions between hydrogen microporosity formation, growth of dendrites and eutectics, and competitive growth among gas pores of different sizes. Investigating the influences of initial hydrogen concentration and cooling rate, it was found that the main portion of porosity formation occurs in the eutectic solidification stage.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2021)
Article
Nanoscience & Nanotechnology
Qing Cai, Changming Fang, Ewan Lordan, Yun Wang, Isaac T. H. Chang, Brian Cantor
Summary: A novel near-eutectic Al-15.0Si-4.1Ni-1.9Fe (wt%) alloy with a ternary eutectic reaction was investigated. The alloy exhibited short nanoscale fibrous morphologies of eutectic Si and (Al,Si)5(Fe,Ni) phases. The newly developed alloy displayed superior mechanical properties at room and elevated temperatures compared with other heat-resistant aluminium alloys, suggesting great potential for industrial applications.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Anuruddha Majumder, Dipankar Chatterjee, Sambhunath Nandy
Summary: During the solidification of Al-Si eutectic alloy, silicon distribution is not uniform, leading to silicon segregation. A four phase Eulerian model is utilized in Ansys Fluent simulation software to track the segregation location and understand the distribution of silicon in the Al-Si matrix. Recalescence phenomena are also observed. The numerical simulation confirms that silicon segregation is approximately 1.08 volume %, with silicon primarily concentrated near the top surface of the simulation domain.
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
(2023)
Article
Materials Science, Multidisciplinary
Bo Hu, Dejiang Li, Zixin Li, Jiangkun Xu, Xueyang Wang, Xiaoqin Zeng
Summary: The hot tearing behavior of the double ternary eutectic alloy system, Al-6Mg-xSi (0 to 6.0 wt pct Si) alloys, was evaluated by a constrained rod casting mold, showing that the types and fractions of solidification phases significantly impact hot tearing susceptibility. The addition of Si content changed the freezing range and eutectic liquid fraction, affecting the nucleation, propagation, and healing of hot tear cracks. Additionally, the drop-in force value on the contraction force curve could predict the hot tearing susceptibility regarding the shrinkage coefficient.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2021)
Article
Chemistry, Physical
Qing Cai, Changming Fang, Chamini Mendis, Isaac T. H. Chang, Brian Cantor
Summary: Eutectic alloys were fabricated from the quaternary Al-Cu-Si-Ni system, and a ternary eutectic reaction was found. The as-solidified microstructure exhibited a lamellar theta-Al2(CuNi) phase and fibrous Si morphology. The thermal stability of the eutectic alloy was investigated, and the Ni solution in theta-Al2(CuNi) phase contributed to its thermal stability.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Metallurgy & Metallurgical Engineering
Feng Mao, Yongfeng Qiao, Po Zhang, Liming Ou, Chong Chen, Cheng Zhang, Yu Wang
Summary: The addition of Eu in Al-7Si alloys changes the morphology of eutectic Si, decreases the number of eutectic cells, increases their size, and lowers the nucleation temperature. Eu also causes phosphorus segregation and affects the growth direction and form of eutectic Si cells.
INTERNATIONAL JOURNAL OF METALCASTING
(2022)
Article
Materials Science, Multidisciplinary
Yasin Alemdag, Sadun Karabiyik, Gencaga Purcek
Summary: In this study, the microstructure and mechanical properties of a severely deformed Al-12Si-3Cu-0.5Mn alloy were investigated. Multi-direction forging (MDF) resulted in the fragmentation of hard particles, formation of dispersoids, and the formation of fine grains with high angle grain boundaries. The alloy exhibited improved hardness, yield and tensile strength, elongation, and impact toughness after MDF. The highest values were achieved after two-cycle MDF for hardness, yield and tensile strength, while four-cycle MDF produced the highest elongation and impact toughness values. The microstructural alterations, including the fragmentation of hard particles, formation of dispersoids and fine grains, annihilation of dislocations, and grain growth, explained these findings.
METALS AND MATERIALS INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
Yinling Jin, Hongze Fang, Shu Wang, Ruirun Chen, Yanqing Su, Jingjie Guo
Summary: The addition of Eu can modify the eutectic Mg2Si phase, improving the mechanical properties of near-eutectic Al-Mg2Si alloys. Tensile properties are significantly enhanced when the Eu content is 0.05%, but they decrease with further increasing Eu content, indicating an over-modification effect.
ADVANCED ENGINEERING MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Leonardo Fernandes Gomes, Cristie Luis Kugelmeier, Amauri Garcia, Carlos Alberto Della Rovere, Jose Eduardo Spinelli
Summary: Commercial casting alloys based on Al-Si are crucial, with their microstructure and properties influenced by the addition of certain alloying elements. Studies have shown that increasing Si content decreases corrosion resistance, while higher Ag content can lead to thicker passive films but reduced resistance against corrosion.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Crystallography
Ahmad Mostafa, Nabeel Alshabatat
Summary: In this study, the microstructure, mechanical properties, and wear behavior of three Al-Si alloys were investigated. It was found that the Al-13.5%Si alloy showed higher microhardness and excellent wear resistance, attributed to the presence of a large amount of Diamond-Si hard phase. On the other hand, the Al-1.5%Si alloy exhibited poorer wear resistance, mainly due to the particle detachment mechanism.
Article
Materials Science, Multidisciplinary
Zhaohua Hu, Qile Huo, Yaxin Chen, Manping Liu, Xuefei Chen
Summary: In this study, the microstructural evolution of the Al-15Si-4Cu-0.5Mg alloy under semisolid slurry conditions using a mechanical rotational barrel system is investigated. The results show that higher rotational speed and pouring temperature result in smaller and more rounded primary Si particles. Moreover, the dendritic aluminum matrix and skeletal iron-containing intermetallics are sheared off during the process, leading to a more uniform and dispersed Al2Cu phase. The rheo-diecasting method improves the microstructure and properties of the alloy, making it promising for various industrial applications.
Article
Materials Science, Multidisciplinary
D. Scheiber, J. Svoboda, F. D. Fischer, H. J. Boehm, L. Romaner
Summary: For designing new and improved materials, it is necessary to predict the kinetics of precipitation and segregation. However, there is currently no available modeling approach that combines precipitation with ab initio segregation data. In this study, we propose a mathematical model that describes segregation and precipitation kinetics using grain boundary segregation energies obtained from ab initio simulations. The model is rigorously implemented and validated using experimental data on a Fe-Au system from literature.
Article
Chemistry, Multidisciplinary
Reza J. J. Kashtiban, Christopher E. E. Patrick, Quentin Ramasse, Richard I. I. Walton, Jeremy Sloan
Summary: Halide perovskite structures formed at the quantum scale are revolutionizing optoelectronic materials design, such as solar cells and light-emitting diodes. Four sub-nanometer halide perovskite structures were successfully created inside single-walled carbon nanotubes, demonstrating unique properties and bandgap widening compared to bulk forms. These structures show promise in the development of advanced optoelectronic devices.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Jack W. Jordan, Alexander Chernov, Graham A. Rance, E. Stephen Davies, Anabel E. Lanterna, Jesum Alves Fernandes, Alexander Gruneis, Quentin Ramasse, Graham N. Newton, Andrei N. Khlobystov
Summary: Boron nitride nanotubes (BNNTs) are highly effective nanocontainers for polyoxometalate (POM) molecules, with spontaneous encapsulation from aqueous solution and Lewis acid-base interactions likely driving the process. Extensive investigation of the guest-molecules revealed energy and electron transfer processes between BNNTs and POMs, leading to various phenomena such as quenching of BNNT photoluminescence, emergence of new photoluminescence emissions, photochromic response, and paramagnetic signals from guest-POMs. These findings provide a fresh perspective on nanoscale host-guest interactions and open pathways for harnessing the functional properties of hybrid systems.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Kenneth J. T. Livi, Mario Villalobos, Quentin Ramasse, Rik Brydson, Hugo Slavko Salazar-Rivera
Summary: The capacity for crystals to adsorb elements and molecules depends on the structures of their crystal faces and their proportions. This study reveals that the surface structure of crystal faces is influenced by surface roughness, which is the main factor controlling the absorption site density. By examining synthetic goethites with different crystal size distributions, it is found that crystal size affects their shape, atomic-scale surface roughness, and total surface site density. The results show that surface roughness increases with the size of synthetic goethites and this leads to an increase in the total site density compared to ideal smooth crystals.
Article
Nanoscience & Nanotechnology
D. Scheiber, M. N. Popov, L. Romaner
Summary: It has been found that the grain boundary segregation energies of solute elements are substantially affected by the vibrational contribution, which affects solute enrichment. Additionally, the results clarify the origin of the entropy of segregation, providing a theoretical basis to supplement previous experimental discussions.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Anastasiia Galakhova, Fabian Kadisch, Gregor Mori, Susanne Heyder, Helmut Wieser, Bernhard Sartory, Jaroslaw Wosik, Sabine Schwarz, Simon Burger
Summary: The corrosion behavior of an unstabilized ferritic stainless steel 1.4016 was studied during the decomposition of aqueous urea solution at high temperature. Corrosion occurred after cyclic heating for 100 hours (from room temperature up to 600 degrees C) and injection of aqueous urea solution onto the steel plate in a laboratory test. Metallographic analysis of the corroded steel samples using high-resolution scanning electron microscopy (HR-SEM) and transmission electron microscopy (TEM) revealed uniform corrosion underneath deposits and the presence of a nitridation layer and chromium carbonitride particles throughout the entire sample depth, resulting in intergranular attack.
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
(2023)
Article
Materials Science, Multidisciplinary
Marina Lukas, Gerald Ressel, Carola Hahn, Sven Eck, Bernhard Sartory, Thomas Titze, Uwe Ossberger
Summary: Hadfield Steel demonstrates high strain hardening attributed to twin formation during mechanical loading. While twin formation in Hadfield Steel is well-documented, detwinning is poorly understood. Detwinning contributes to plastic deformation and may be crucial during cyclic loading. This study focuses on the twinning and detwinning behavior in Hadfield Steel through interrupted tensile tests conducted within a scanning electron microscope. Electron backscatter diffraction analysis reveals the appearance of the first twins after 5 to 10 pct strain, and partial detwinning at 30 and 40 pct elongation. Kernel Average Misorientation analysis indicates high misorientation in both twinned and detwinned regions, linking it to the twinning/detwinning process.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Rishi Bodlos, Daniel Scheiber, Juergen Spitaler, Lorenz Romaner
Summary: Cu/W composites are widely used due to their suitable thermomechanical properties. The bonding behavior of Cu/W and Cu/WTi interfaces is of economic interest, particularly regarding impurities' effects on the interface behavior. In this study, atomistic models of these interfaces were created and compared to known interfaces, with a focus on the effect of segregation on interface cohesion. Results showed that investigated impurities weaken the interface cohesion.
Article
Chemistry, Multidisciplinary
Vasileios Fotopoulos, David Mora-Fonz, Manuel Kleinbichler, Rishi Bodlos, Ernst Kozeschnik, Lorenz Romaner, Alexander L. Shluger
Summary: In this study, computational modeling was used to investigate the structures, formation energies, and migration mechanisms of vacancy clusters in fcc metals. The results showed that di-vacancies have a smaller migration barrier compared to mono-vacancies and other clusters, and this barrier is further reduced at grain boundaries. These findings are important for understanding the structural evolution and diffusion mechanisms of metal films under thermal and mechanical stress.
Article
Materials Science, Multidisciplinary
Rahulkumar Jagdishbhai Sinojiya, Priya Paulachan, Fereshteh Falah Chamasemani, Rishi Bodlos, Rene Hammer, Jakub Zalesak, Michael Reisinger, Daniel Scheiber, Jozef Keckes, Lorenz Romaner, Roland Brunner
Summary: Nanocrystalline alloy thin films with attractive properties such as high hardness, strength, and wear resistance are often plagued by large residual stresses resulting from their fabrication by deposition. In this study, the impact of minority element concentration on residual stresses in a tungsten-titanium film was investigated using experimental and modelling approaches. Micro-cantilever samples were used for local residual stress measurements, and machine learning techniques were employed for data extraction and stress prediction. The results were correlated with microstructure, elemental analysis, and atomistic modelling, revealing the significant effect of titanium enrichment on stress stored in the nanocrystalline thin film.
COMMUNICATIONS MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Shihao Wang, Yun Wang, Quentin M. Ramasse, Rainer Schmid-Fetzer, Zhongyun Fan
Summary: In this study, the segregation of yttrium (Y) at interfaces between native MgO particles and Mg in an Mg-0.5Y alloy was investigated using state-of-the-art aberration-corrected STEM and associated spectroscopy. Two different 2-dimensional compounds (2DCs) were discovered at the Mg/{111}MgO interface and the Mg/{100}MgO interface, including two atomic layers of a face-centered cubic Y2O3 phase and an Mg(Y)-O monolayer that perfectly matched the {100}MgO plane, respectively. The formation mechanisms of the 2DCs, their effects on the nucleation potency of MgO particles, and grain refinement were discussed.
Article
Materials Science, Multidisciplinary
Ayush Suhane, Daniel Scheiber, Vsevolod I. Razumovskiy, Matthias Militzer
Summary: Atomistically-informed phase field simulations were conducted to investigate the effect of five common alloying elements (Nb, Ti, Mo, V, Mn) on austenite grain growth. Anisotropic simulations based on the segregation energy profiles of the solutes to different grain boundary types suggested a secondary role of solute drag anisotropy on grain growth. The solute trends were found to be the same for all investigated grain boundaries, with Nb being the most effective in retarding austenite grain growth.
COMPUTATIONAL MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Hariharan Umashankar, Daniel Scheiber, Vsevolod I. Razumovskiy, Matthias Militzer
Summary: Solute segregation in alloys, affecting material characteristics, is investigated using DFT calculations in a bcc Ti-25 at % Mo alloy. The energies of segregation of Y, Zr, and Nb to a & sigma;5 grain boundary are determined. Different scenarios are considered to calculate the distribution of segregation energies, with solute atoms preferring to segregate to a Mo site rather than a Ti site at the GB plane. Segregation energy trends can be rationalized based on elastic interactions, with Y having the highest segregation energies followed by Zr and Nb.
COMPUTATIONAL MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Gerfried Millner, Manfred Muecke, Lorenz Romaner, Daniel Scheiber
Summary: In this study, AI regression models are used to predict the r-value, tensile strength, yield stress, and elongation at fracture of steel coils based on their chemical composition and process parameters. The dataset consists of chemical analysis, process parameters, and mechanical properties obtained from tensile tests during steel production. The data is cleaned and preprocessed to create a machine-readable dataset suitable for training various AI models such as Random Forest Regression, Support Vector Regression, Artificial Neural Networks, and Extreme Gradient Boost. The performance of each model is evaluated through hyperparameter tuning, training, and comparison of prediction accuracy. Additionally, feature importance determination techniques are applied to understand the impact of information from different steps in the models.
