Advances in Characterization of Heterogeneous Metals/Alloys

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 27708

Special Issue Editor

Special Issue Information

Dear Colleagues,

This Special Issue aims to provide a good forum for scientists and engineers to share and discuss their pioneering original findings or insightful reviews on the characterization of heterogeneous metals/alloys. Reports on the development of a new characterization method and/or the application of multiple and complementary characterization methods towards the enhancement of process and application of metals and/or alloys are particularly welcome.

Proper characterization of heterogeneous materials is a challenging task, since the majority of characterization methods analyze either the average characteristics of the whole material or a narrow area of specific interest [1]. This could overlook the correlation between the microscopic structure of fine grains and the macroscopic mechanical behavior of metals/alloys, for example. Such correlations were found to be useful in many different aspects, while research gaps have been identified in terms of the advancement of characterization methods. On the other hand, gaining a better understanding of heterogeneous metals/alloys is of great importance from scientific and engineering points of view, since processing, and producing and applying, these materials, including advanced technologies (e.g. batteries, printed circuit boards), is vital to our modern society.

References

  1. Otsuki, A.; Chen, Y.; Zhao, Y. Characterisation and beneficiation of complex ores for sustainable use of mineral resources: Refractory gold ore beneficiation as an example. Int. J. Soc. Mat. Eng. Res. 2014, 20, 126–135.

Prof. Akira Otsuki
Guest Editor

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Keywords

  • In-situ measurement
  • Operando measurement
  • Neutrons, X-rays
  • Imaging (e.g., SEM, TEM, and tomography/radiography)
  • Surface analysis (e.g., AFM, STM, XPS, XAFS, reflectometry, and mass spectrometry)
  • Complexity and functionality
  • Microstructure and mechanical properties

Published Papers (9 papers)

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Research

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14 pages, 7041 KiB  
Article
Characteristics for Gallium-Based Liquid Alloys of Low Melting Temperature
by Jianfei Shentu, Jiatong Pan, Hao Chen, Chunlin He, Youbin Wang, Gjergj Dodbiba and Toyohisa Fujita
Metals 2023, 13(3), 615; https://doi.org/10.3390/met13030615 - 19 Mar 2023
Cited by 6 | Viewed by 3165
Abstract
Gallium alloys are ideal base carriers for temperature-sensitive ferrofluids, which can be used for energy convection, soft robotics, microchannels, magnetorheological devices, etc. In this study, gallium was mixed with different substances (In, Sn, Zn, Ge, and Al) to obtain a low melting point, [...] Read more.
Gallium alloys are ideal base carriers for temperature-sensitive ferrofluids, which can be used for energy convection, soft robotics, microchannels, magnetorheological devices, etc. In this study, gallium was mixed with different substances (In, Sn, Zn, Ge, and Al) to obtain a low melting point, reduce the wetness and adhesion of its alloys, and realize low viscosity. The melting point, contact angle on certain solid plates, viscosity, and viscoelasticity of the gallium alloys were measured, and some useful gallium alloys were obtained. The experimental results showed that Ga80In10Sn10 had lower wettability at a larger contact angle of 148.6° on the Teflon plate. Here, (Ga80In10Sn10)97Zn3 with a melting point of 8.2 °C, lower than the melting point of Galinstan, was developed. It had a viscosity about three times that of water at room temperature and an elastic response from 0.1 to 100 Hz at a 1% strain amplitude for the viscoelasticity. It was expected that a kind of temperature-sensitive magnetic fluid with a gallium-based liquid alloy as the base carrier liquid would be prepared in the future with Teflon as the container to achieve energy conversion under the drive of the magnetic field. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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38 pages, 9885 KiB  
Article
Coupling Flotation Rate Constant and Viscosity Models
by Mohsin Sajjad and Akira Otsuki
Metals 2022, 12(3), 409; https://doi.org/10.3390/met12030409 - 26 Feb 2022
Cited by 4 | Viewed by 1897
Abstract
In a flotation process, the particle–bubble and particle–particle interactions are key factors influencing collection efficiencies. In this work, the generalized Sutherland equation collision model and the modified Dobby–Finch attachment model for potential flow conditions were used to calculate the efficiencies of particle–bubble collision [...] Read more.
In a flotation process, the particle–bubble and particle–particle interactions are key factors influencing collection efficiencies. In this work, the generalized Sutherland equation collision model and the modified Dobby–Finch attachment model for potential flow conditions were used to calculate the efficiencies of particle–bubble collision and attachment, respectively, for a flotation particle size of 80 μm. The negative effects of increase in the suspension viscosity due to the presence of fine particles on the flotation performance of fine particles have been reported, but there is no overarching model coupling the suspension viscosity and the flotation performance in the literature. Therefore, our study addressed this very important research gap and incorporated the viscosity model as a function of solid concentration, shear rate, and particle size into a flotation rate constant model that was proposed and conducted for the first time. This is quite a unique approach because the previously developed flotation rate constant model has never been coupled with a suspension rheology model taking into account the solid particle concentration and shear rate, although they are very important flotation variables in practice. The effect of the presence of ultra-fine/fine particles on the viscosity of the suspension and the flotation efficiencies and rate constant of flotation particle size of 80 μm were also investigated in order to better understand the mechanism of the problematic behavior of ultra-fine/fine particles in flotation. This coupling study started with the simplest case: flowing suspensions of inert, rigid, monomodal spherical particles (called hard spheres). Even for hard spheres, the effect of shear rate and particle size which produces deviation from the ideal case (constant viscosity at constant temperature regardless of shear rate) was clearly identified. It was found that the suspension viscosity increases with the decrease in fine/ultra-fine particle size (i.e., 1 µm–8 nm) and at higher solid particle concentration. Then, the colloidal particle suspensions, where interparticle forces play a significant role, were also studied. The suspension viscosity calculated for both cases was incorporated into the flotation efficiencies and rate constant models and discussed in terms of the effects of the presence of ultra-fine and fine particles on the flotation kinetics of flotation particle size of 80 μm. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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14 pages, 5807 KiB  
Article
Effect of La Addition on Microstructure and Properties of Al-0.2Fe-0.06Cu Alloy
by Yawu Xu, Zixuan Peng, Dongyan Ding, Wenlong Zhang, Yongjin Gao, Guozhen Chen, Yonglin Xie and Yongqi Liao
Metals 2022, 12(2), 211; https://doi.org/10.3390/met12020211 - 24 Jan 2022
Cited by 1 | Viewed by 1994
Abstract
The increasing application of lithium-ion batteries has led to higher requirements being imposed on the performance of current collectors. In this work, the effect of La content on the microstructure and properties of Al-0.2Fe-0.06Cu alloy was invested through optical microscopy, scanning electron microscopy [...] Read more.
The increasing application of lithium-ion batteries has led to higher requirements being imposed on the performance of current collectors. In this work, the effect of La content on the microstructure and properties of Al-0.2Fe-0.06Cu alloy was invested through optical microscopy, scanning electron microscopy and mechanical/electrical/electrochemical performance tests. Experimental results indicated that the addition of La was beneficial to grain refinement and promote the formation of La-containing compounds. However, excessive La addition weakened the refinement effect. Grain refinement played a major role in affecting the mechanical properties of the alloy, but had little effect on the conductivity. In comparison with Al-0.2Fe-0.06Cu, the La-containing alloys had lower corrosion potential, which indicated that the addition of La element could improve the corrosion resistance of the Al-0.2Fe-0.06Cu alloy. The addition of La improved the mechanical properties of the alloy at room temperature and 50 °C. When the La addition was 0.1wt.%, the alloy had the best mechanical properties. The corrosion resistance of the alloy continued to improve with increases in the La content. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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13 pages, 16236 KiB  
Article
Microstructure of Al-5Cu-1Li-0.6Mg-0.5Ag-0.5Mn Alloys
by Wenzheng Chen, Wenlong Zhang, Dongyan Ding and Daihong Xiao
Metals 2021, 11(1), 37; https://doi.org/10.3390/met11010037 - 26 Dec 2020
Cited by 6 | Viewed by 2137
Abstract
Microstructural optimization of Al-Li alloys plays a key role in the adjustment of mechanical properties as well as corrosion behavior. In this work, Al-5Cu-1Li-0.6Mg-0.5Ag-0.5Mn alloy was homogenized at different temperatures and holding times, followed by aging treatment. The microstructure and composition of the [...] Read more.
Microstructural optimization of Al-Li alloys plays a key role in the adjustment of mechanical properties as well as corrosion behavior. In this work, Al-5Cu-1Li-0.6Mg-0.5Ag-0.5Mn alloy was homogenized at different temperatures and holding times, followed by aging treatment. The microstructure and composition of the homogenized alloys and aged alloys were investigated. There were Al7Cu4Li phase, Al3Li phase, and Al2CuLi phases in the homogenized alloys. The Al7Cu4Li phase was dissolved with an increase in homogenization temperature and holding time. Al2Cu phase and Al2CuLi phase coarsened during the homogenization process. The alloy homogenized at 515 °C for 20 h was subjected to a two-stage aging treatment. Peak-age alloy, which had gone through age treatment at 120 °C for 4 h and 180 °C for 6 h, was mainly composed of α-Al, Al20Cu2Mn3, Al2CuLi, Al2Cu, and Al3Li phases. Tafel polarization of the peak-age alloys revealed the corrosion potential and corrosion current density to be −779 mV and 2.979 μA/cm2, respectively. The over-age alloy had a more positive corrosion potential of −658 mV but presented a higher corrosion current of 6.929 μA/cm2. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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11 pages, 4738 KiB  
Article
Robust Ag-Cu Sintering Bonding at 160 °C via Combining Ag2O Microparticle Paste and Pt-Catalyzed Formic Acid Vapor
by Liangliang He, Junlong Li, Xin Wu, Fengwen Mu, Yinghui Wang, Yangting Lu and Tadatomo Suga
Metals 2020, 10(3), 315; https://doi.org/10.3390/met10030315 - 28 Feb 2020
Cited by 11 | Viewed by 3546
Abstract
With the assistance of Pt-catalyzed formic acid vapor, robust Ag-Cu bonding was realized at an ultra-low temperature of 160 °C under 3 MPa for 30 min via the sintering of Ag nanoparticles in situ generated from Ag2O microparticles. The Cu oxide [...] Read more.
With the assistance of Pt-catalyzed formic acid vapor, robust Ag-Cu bonding was realized at an ultra-low temperature of 160 °C under 3 MPa for 30 min via the sintering of Ag nanoparticles in situ generated from Ag2O microparticles. The Cu oxide layer at the interface after bonding can be eliminated, which improves the bond strength and electrical conductivity of the joint. A metallic bond contact between the sintered Ag and the Cu substrate is obtained without interfacial solid solution and intermetallic phases, and the shear strength is comparable to previous bonding at a higher temperature. The bonding mechanisms were figured out by comparing the bonding with and without the Pt-catalyzed formic acid vapor. This ultra-low temperature Ag-Cu bonding method may create more flexibilities in the structure design and material selection for power device integration. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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10 pages, 3881 KiB  
Article
Al–Fe–Si–La Alloys for Current Collectors of Positive Electrodes in Lithium Ion Batteries
by Xin Yang, Dongyan Ding, Yawu Xu, Wenlong Zhang, Yongjin Gao, Zhanlin Wu, Guozhen Chen, Renzong Chen, Yuanwei Huang and Jinsong Tang
Metals 2020, 10(1), 109; https://doi.org/10.3390/met10010109 - 10 Jan 2020
Cited by 2 | Viewed by 2467
Abstract
Al–xFe–Si–La alloys (x = 0.07, 0.2, 0.4 wt. %) were designed as current collectors of positive electrodes in lithium ion batteries, and the microstructure, tensile strength, electrical conductivity and corrosion resistance of the alloys were investigated with scanning electron microscopy (SEM) and energy [...] Read more.
Al–xFe–Si–La alloys (x = 0.07, 0.2, 0.4 wt. %) were designed as current collectors of positive electrodes in lithium ion batteries, and the microstructure, tensile strength, electrical conductivity and corrosion resistance of the alloys were investigated with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), a tensile test, an electrical conductivity test, and an electrochemical test. It was found that the amount of Fe content greatly affected the quantity of the second phases in the alloys. The higher the Fe content was, the more the second phases were. With increase of the Fe content, the tensile strength and corrosion resistance of the Al–xFe–Si–La alloys were improved, and the electrical conductivity of the Al–xFe–Si–La alloys could meet the application requirements. Compared to the Al–0.07Fe–0.1Si–0.07La alloy, the strength of the Al–0.4Fe–0.1Si–0.07La alloy was greatly enhanced. The Al–0.4Fe–0.1Si–0.07La alloy also had a higher corrosion potential than that of the Al–0.07Fe–0.1Si–0.07La alloy. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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17 pages, 6332 KiB  
Article
Selective Milling and Elemental Assay of Printed Circuit Board Particles for Their Recycling Purpose
by Akira Otsuki, Pedro Pereira Gonçalves and Emilien Leroy
Metals 2019, 9(8), 899; https://doi.org/10.3390/met9080899 - 16 Aug 2019
Cited by 26 | Viewed by 3877
Abstract
Selective/preferential milling of printed circuit board (PCB) particles followed by non-destructive characterization of the mill products was performed in order to understand the effects of different feed masses into a hammer mill and different milling time on the metal recovery and enrichment ratio. [...] Read more.
Selective/preferential milling of printed circuit board (PCB) particles followed by non-destructive characterization of the mill products was performed in order to understand the effects of different feed masses into a hammer mill and different milling time on the metal recovery and enrichment ratio. Those are important variables affecting and determining the process performance and capacity. The milling tests and elemental assay characterization were conducted by using a hammer mill and a portable X-ray fluorescence analysis (XRF), respectively. The results showed the preferential metal concentration/enrichment was achieved for several elements and their degree was varied depending on the parameters. Using the experimental data, predictive models of metal recovery were developed and the global trend of metal recoveries was observed under different mill feed and milling time and discussed. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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10 pages, 6274 KiB  
Article
Tensile Properties and Corrosion Resistance of Al-xFe-La Alloys for Aluminium Current Collector of Lithium-Ion Batteries
by Xin Yang, Dongyan Ding, Yawu Xu, Wenlong Zhang, Yongjin Gao, Zhanlin Wu, Guozhen Chen, Renzong Chen, Yuanwei Huang and Jinsong Tang
Metals 2019, 9(6), 706; https://doi.org/10.3390/met9060706 - 24 Jun 2019
Cited by 3 | Viewed by 3320
Abstract
Al-xFe-La alloys (x = 0.07, 0.1, 0.2) for aluminum current collectors of lithium-ion batteries were prepared and the microstructure of Al-0.07Fe-0.07La, Al-0.1Fe-0.07La and Al-0.2Fe-0.07La aluminum alloys were observed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS). The experimental results showed that with [...] Read more.
Al-xFe-La alloys (x = 0.07, 0.1, 0.2) for aluminum current collectors of lithium-ion batteries were prepared and the microstructure of Al-0.07Fe-0.07La, Al-0.1Fe-0.07La and Al-0.2Fe-0.07La aluminum alloys were observed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS). The experimental results showed that with the increase of Fe content, the size of the second phases in Al-xFe-0.07La alloys became finer and more dispersed and that the microstructure of the alloy had improved. The strength and corrosion resistance of Al-xFe-La alloys were studied by tensile tests and electrochemical tests and the morphological investigations of samples were also conducted by SEM and EDS. With the increase of Fe content, the strength and corrosion resistance of Al-xFe-La alloys became better. Compared to Al-0.07Fe-0.07La alloy, the yield strength and tensile strength of the Al-0.2Fe-0.07La alloy increased by 51.19% and 58.48% respectively, and the elongation increased by 88.41%. Moreover, Al-0.2Fe-0.07La alloy had much more positive corrosion potential and much smaller corrosion current than those of Al-0.07Fe-0.07La alloy. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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Review

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31 pages, 15290 KiB  
Review
Correlation between Flotation and Rheology of Fine Particle Suspensions
by Mohsin Sajjad and Akira Otsuki
Metals 2022, 12(2), 270; https://doi.org/10.3390/met12020270 - 01 Feb 2022
Cited by 9 | Viewed by 3451
Abstract
This paper summarizes and discusses previous investigations into the correlation between the rheology and flotation process of fine particle suspensions. This summary provides a better understanding of the challenges and current status of this subject and useful feedback based on the revision of [...] Read more.
This paper summarizes and discusses previous investigations into the correlation between the rheology and flotation process of fine particle suspensions. This summary provides a better understanding of the challenges and current status of this subject and useful feedback based on the revision of relevant theories and practical implications for fine particle characterization and processing. Such processes include the sustainable beneficiation of complex ores and wastes for valuable material extraction and the segregation of toxic substances. For example, there has been increasing demand for the beneficiation of complex ores often carrying the values (e.g., critical raw materials) in fine grains, due to the noticeable decrease in the accessibility of high-grade and easily extractable ores. To maintain the sustainable use of limited resources, the effective beneficiation of complex ores is urgently required. It can be successfully achieved only with selective particle/mineral dispersion/liberation and the assistance of mineralogical and fine particle characterization including a proper understanding of the rheological behavior of complex ores in the context of fine particle separation/processing. In correlating flotation with suspension rheology, previous works were summarized and we found that the modeling of their correlations as well as comprehensive contributions of pulp and froth rheology on flotation performance have been studied very limitedly, and comprehensive developments in these aspects are thus strongly suggested. Full article
(This article belongs to the Special Issue Advances in Characterization of Heterogeneous Metals/Alloys)
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