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Metals
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Phase Transformations in Aluminium Alloys
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Phase Transformations in Aluminium Alloys

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

Deadline for manuscript submissions: closed (31 July 2020) | Viewed by 26251

Special Issue Editor

Prof. Daniel Larouche

E-Mail Website
Guest Editor
Department of mining, metallurgy and materials engineering, REGAL—Research Center, Laval University, 1065 Avenue de la Médecine, Quebec G1V 0A6, Canada
Interests: phase transformations; casting; heat treating; calorimetric analysis

Special Issue Information

Dear Colleagues,

Aluminium alloys are widely used nowadays because they combine a set of properties depending largely on the microstructure obtained after a sequence of phase transformations including solidification, homogenization, and solid-state precipitation. The complexity of these transformations in commercial alloys is still very challenging, as our understanding of the kinetics aspects is still mainly based on concepts developed on binary alloys transformed under strict, controlled conditions. With the developments of alloys dedicated to operating at high temperatures and incorporating minor additions of high melting point or transition elements, one must better assess the factors making these additions to be detrimental or beneficial and develop guidelines helping the optimization of alloy compositions for a given set of operating conditions. For alloys processed following non-conventional routes like additive manufacturing (powder bed fusion, selective laser sintering, etc.), friction stir welding, spray forming, etc., there is a strong need for a better understanding of the critical transformation processes involved, particularly when multicomponent alloys are used. A lot of research must still be done to better characterize and model phase transformations in aluminium alloys occurring under a variety of conditions and compositions.

The Special Issue is therefore dedicated to contributions in the field of phase transformations in aluminium alloys revealing the marked effect on the microstructure that alloy composition and temperature history may have, including the morphology and size of grains and second phase particles.

Prof. Daniel Larouche
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Aluminium alloys
  • Phase transformation
  • Precipitation kinetics
  • Solidification
  • Homogenization
  • Nucleation
  • Growth
  • Ostwald ripening
  • Aging
  • Hardening

Published Papers (7 papers)

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Research

9 pages, 2352 KiB  
Article
Quantification and Modelling of the Multiphase-Coupled Strengthening Effect in Al-Cu-Li Alloy
by Jin Zhang, Zhide Li, Fushun Xu and Chongjun Bao
Metals 2019, 9(10), 1038; https://doi.org/10.3390/met9101038 - 24 Sep 2019
Cited by 6 | Viewed by 2134
Abstract
After aging heat treatment, Al-Cu-Li alloy, in general, contains a variety of precipitated phases that jointly influence the age-strengthening effect on the alloy. In this work, a multiphase-coupled strengthening model has been established on the basis of a dislocation bypassing mechanism. The model [...] Read more.
After aging heat treatment, Al-Cu-Li alloy, in general, contains a variety of precipitated phases that jointly influence the age-strengthening effect on the alloy. In this work, a multiphase-coupled strengthening model has been established on the basis of a dislocation bypassing mechanism. The model considered situations with different proportions of two strengthening phases, T1 and θ′, and then obtained the dimension and volume fractions of these two strengthening phases via experiments. The values predicted by the multiphase-coupled strengthening model and the classical strengthening superposition model were compared with the measured results. The multiphase-coupled strengthening model established in this work had better consistency with the measured results. Moreover, the modeling method proposed in the paper can also be extended to the system having over two primary strengthening phases. Hence, the model can contribute towards the development of a multi-component precipitation strengthening process for aluminum alloys. Full article
(This article belongs to the Special Issue Phase Transformations in Aluminium Alloys)
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12 pages, 3368 KiB  
Article
Influence of Preaging Treatment on Bake-Hardening Response and Electrochemical Corrosion Behavior of High Strength Al-Zn-Mg-Cu-Zr Alloy
by Hui Li, Xiao-Teng Liu and Jia-Yi Wang
Metals 2019, 9(8), 895; https://doi.org/10.3390/met9080895 - 15 Aug 2019
Cited by 3 | Viewed by 3364
Abstract
The influence of preaging (PA) treatments on the bake hardening (BH) response of a AlZnMgCuZr aluminum alloy which served as automotive body structures were studied in this paper. A novel two-step PA treatment was particularly designed and further employed. The mechanical properties of [...] Read more.
The influence of preaging (PA) treatments on the bake hardening (BH) response of a AlZnMgCuZr aluminum alloy which served as automotive body structures were studied in this paper. A novel two-step PA treatment was particularly designed and further employed. The mechanical properties of the alloy were tested in detail. The microstructure was characterized by optical microscope (OM), transmission electron microscopy (TEM) and 3D measuring laser microscope (3D–MLM). Meanwhile, the corrosion behavior was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results indicated that the PA treatment was beneficial for the improvement of BH response after baking at 180 °C immediately after the solution treatment and the micro-hardness reached the peak value (194 HV) after 10 h holding, which had a percentage improvement of 110.87% compared to the hardness under the solution condition. The PA treatments decreased natural aging (NA) adverse effects, while it had the lowest NA effect and optimal BH response under 120 °C/20 min. Such a novel two-step PA treatment was revealed further to decrease the NA effect and increase the BH response compared to the optimal PA treatment, in particular, the BH value could reach 168 MPa and was 21.7% higher than that of optimal PA + NA treatment. The optimal corrosion resistance has been shown up by the combined characterizations of potentiodynamic polarization curves, EIS Nyquist plots, and 3D–MLM images. Full article
(This article belongs to the Special Issue Phase Transformations in Aluminium Alloys)
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15 pages, 4959 KiB  
Article
Analytical Modeling of the Mixed-Mode Growth and Dissolution of Precipitates in a Finite System
by Tohid Naseri, Daniel Larouche, Rémi Martinez, Francis Breton and Denis Massinon
Metals 2019, 9(8), 889; https://doi.org/10.3390/met9080889 - 14 Aug 2019
Cited by 5 | Viewed by 2655
Abstract
In this paper, a novel analytical modeling of the growth and dissolution of precipitates in substitutional alloys is presented. This model uses an existing solution for the shape-preserved growth of ellipsoidal precipitates in the mixed-mode regime, which takes into account the interfacial mobility [...] Read more.
In this paper, a novel analytical modeling of the growth and dissolution of precipitates in substitutional alloys is presented. This model uses an existing solution for the shape-preserved growth of ellipsoidal precipitates in the mixed-mode regime, which takes into account the interfacial mobility of the precipitate. The dissolution model is developed by neglecting the transient term in the mass conservation equation, keeping the convective term. It is shown that such an approach yields the so-called reversed-growth approximation. A time discretization procedure is proposed to take into account the evolution of the solute concentration in the matrix as the phase transformation progresses. The model is applied to calculate the evolution of the radius of spherical θ-Al2Cu precipitates in an Al rich matrix at two different temperatures, for which growth or dissolution occurs. A comparison of the model is made, with the results obtained using the numerical solver DICTRA. The very good agreement obtained for cases where the interfacial mobility is very high indicates that the time discretization procedure is accurate. Full article
(This article belongs to the Special Issue Phase Transformations in Aluminium Alloys)
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17 pages, 3633 KiB  
Article
Precipitation Kinetics and Evaluation of the Interfacial Mobility of Precipitates in an AlSi7Cu3.5Mg0.15 Cast Alloy with Zr and V Additions
by Pierre Heugue, Daniel Larouche, Francis Breton, Denis Massinon, Rémi Martinez and X.-Grant Chen
Metals 2019, 9(7), 777; https://doi.org/10.3390/met9070777 - 11 Jul 2019
Cited by 13 | Viewed by 4044
Abstract
Recent environmental restrictions constrained car manufacturers to promote cast aluminum alloys working at high temperatures (180 °C–300 °C). The development of new alloys permits the fabrication of higher-strength components in engine downsizing. Those technologies increase internal loadings and specific power and stretch current [...] Read more.
Recent environmental restrictions constrained car manufacturers to promote cast aluminum alloys working at high temperatures (180 °C–300 °C). The development of new alloys permits the fabrication of higher-strength components in engine downsizing. Those technologies increase internal loadings and specific power and stretch current materials to their limits. Transition metals in aluminum alloys are good candidates to improve physical, mechanical, and thermodynamic properties with the aim of increasing service life of parts. This study is focused on the modified AlSi7Cu3.5Mg0.15 alloy where Mn, Zr, and V have been added as alloying elements for high-temperature applications. The characterization of the cast alloy in this study helps to evaluate and understand its performance according to their physical state: As-cast, as-quenched, or artificially aged. The precipitation kinetics of the AlSi7Cu3.5Mg0.15 (Mn, Zr, V) alloy has been characterized by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) observations, and micro-hardness testing. The Kissinger analysis was applied to extract activation energies from non-isothermal DSC runs conducted at different stationary heating rates. Finally, first-order evaluations of the interfacial mobility of precipitates were obtained. Full article
(This article belongs to the Special Issue Phase Transformations in Aluminium Alloys)
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10 pages, 6158 KiB  
Article
Annealing Response of a Cold-Rolled Binary Al–10Mg Alloy
by Lei Feng, Jianguo Li, Chunfa Huang and Jinxian Huang
Metals 2019, 9(7), 759; https://doi.org/10.3390/met9070759 - 05 Jul 2019
Cited by 7 | Viewed by 3328
Abstract
The effect of annealing temperature on microstructure and mechanical properties of a cold-rolled Al–10Mg alloy has been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and tensile testing. The results showed that supersaturated Mg precipitated along grain boundaries [...] Read more.
The effect of annealing temperature on microstructure and mechanical properties of a cold-rolled Al–10Mg alloy has been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and tensile testing. The results showed that supersaturated Mg precipitated along grain boundaries and deformation bands during annealing treatment and precipitation size and the concentration of solid solution Mg atoms increased with the rising of annealing temperature. When annealed at low temperature, accumulation and annihilation of dislocations were the primary way of recovery; as temperature increased to 300 °C, recrystallized grains were formed around the large size β phase through particle-stimulated nucleation. A high ultimate strength (550 MPa) and a middle ductility (14%) were obtained when the Al–10Mg alloy was annealed at 200 °C for 1 h. The abnormal decrease of elongation when the Al–10Mg alloy was annealed at 250–300 °C was due to the formation of a continuous network distribution of large size β phase particles along grain boundaries. Full article
(This article belongs to the Special Issue Phase Transformations in Aluminium Alloys)
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27 pages, 28569 KiB  
Article
Influences of Cu Content on the Microstructure and Strengthening Mechanisms of Al-Mg-Si-xCu Alloys
by Yuqiang Chen, Qiang Hu, Suping Pan, Hao Zhang, Huiqun Liu, Biwu Zhu, Xiao Liu and Wenhui Liu
Metals 2019, 9(5), 524; https://doi.org/10.3390/met9050524 - 07 May 2019
Cited by 12 | Viewed by 4295
Abstract
The effects of the Cu content on the microstructure and strengthening mechanisms of the Al-Mg-Si-xCu alloys were systematically investigated using scanning electron microscopy (SEM), electron probe microanalysis (EPMA), transmission electron microscopy (TEM), and mechanical tensile tests. The results show that, the [...] Read more.
The effects of the Cu content on the microstructure and strengthening mechanisms of the Al-Mg-Si-xCu alloys were systematically investigated using scanning electron microscopy (SEM), electron probe microanalysis (EPMA), transmission electron microscopy (TEM), and mechanical tensile tests. The results show that, the strengthening mechanisms change with the Cu content. For as-quenched alloys, solution strengthening (σSS) is predominant when the Cu content ≥2.5 wt.%, and of equivalent importance as grain size strengthening (σH-P) when the Cu content ≤1.0 wt.%. With respect to peak-aged alloys, precipitation strengthening (σppt) is predominant when the Cu content ≥2.5 wt.%, but σSS becomes predominant when the Cu content is 4.5 wt.%. As the Cu content increases from 0.5 to 4.5 wt.%, the main type of precipitates in alloy tends to change from a β″ phase to Q′ phase, and then to a θ′ phase. Among the three types of precipitates, θ′-precipitate causes the largest increase in yield strength (σ0.2) and the largest decrease rate in elongation. β″-precipitate leads to the smallest increase in σ0.2 and the smallest decrease rate in elongation. The increase of Cu content reduces Si solubility in the Al matrix and thus decreases the nucleation rate of β″ phase during subsequent aging. Full article
(This article belongs to the Special Issue Phase Transformations in Aluminium Alloys)
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10 pages, 7556 KiB  
Article
Effect of Eutectic Mg2Si Phase Modification on the Mechanical Properties of Al-8Zn-6Si-4Mg-2Cu Cast Alloy
by Byung Joo Kim, Sung Su Jung, Ji Hoon Hwang, Yong Ho Park and Young Cheol Lee
Metals 2019, 9(1), 32; https://doi.org/10.3390/met9010032 - 02 Jan 2019
Cited by 16 | Viewed by 4407
Abstract
The modification effect of Al-5Ti-1B master alloy on eutectic Mg2Si in Al-Zn-Si-Mg system alloy was investigated in this study. The microstructure shows that an extreme effect can be achieved after the addition of Al-5Ti-1B master alloy into the base alloy. The [...] Read more.
The modification effect of Al-5Ti-1B master alloy on eutectic Mg2Si in Al-Zn-Si-Mg system alloy was investigated in this study. The microstructure shows that an extreme effect can be achieved after the addition of Al-5Ti-1B master alloy into the base alloy. The morphology of eutectic Mg2Si changed from Chinese script to fine polygonal shape, and the size was refined from over 50 μm to under 10 μm. This morphology change is believed to be due to TiB2 particles existing in Al-5Ti-1B master alloy, and the presence of TiB2 particles inside the modified Mg2Si was confirmed by scanning electron microscope/energy dispersive spectrometer (SEM/EDS) observation. The mechanical properties were also improved by the addition of Al-5Ti-1B master alloys. This study investigated the reason for the improvement in mechanical properties with the modification of the microstructure. Full article
(This article belongs to the Special Issue Phase Transformations in Aluminium Alloys)
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