Special Issue "Light Weight Alloys: Processing, Properties and Their Applications"

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

Deadline for manuscript submissions: 28 February 2018

Special Issue Editors

Guest Editor
Prof. Dr. Maurizio Vedani

Dipartimento di Meccanica, Politecnico di Milano, Via Giuseppe La Masa 1, 20156 Milano, Italy
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Interests: metallurgy of light alloys; additive manufacturing of metals; plastic deformation of steels and non-ferrous alloys; thermomechanical and surface treatments of metals
Guest Editor
Dr. Riccardo Casati

Department of Mechanical Engineering, Politecnico di Milano, Via Giuseppe La Masa 1, 20156 Milano, Italy
Website | E-Mail
Interests: light alloys, nanocomposites and steels processed by additive manufacturing and powder metallurgy processes

Special Issue Information

Dear Colleagues,

Light metallic alloys are continuously gaining growing interest for a wide number of applications owing to energy saving and environmental sustainability issues, as well as good processability for the easy shaping of parts and biocompatibility for medical applications (especially for Ti and Mg).

The aim of this Special Issue is to highlight recent innovations introduced in the fields of light alloys considering the perspectives of new materials and related processing routes and of new fields of applications and design strategies in these sectors.

Prof. Maurizio Vedani
Dr. Riccardo Casati
Guest Editors

Manuscript Submission Information

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Keywords

  • Aluminum alloys
  • Titanium alloys
  • Magnesium alloys
  • Innovative Processing routes
  • Advanced design and applications

Published Papers (11 papers)

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Research

Open AccessArticle Fabrication of an Ultra-Fine Grained Pure Titanium with High Strength and Good Ductility via ECAP plus Cold Rolling
Metals 2017, 7(12), 563; doi:10.3390/met7120563
Received: 6 November 2017 / Revised: 29 November 2017 / Accepted: 8 December 2017 / Published: 14 December 2017
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Abstract
Microstructure evolutions and mechanical properties of a commercially pure titanium (CP-Ti, grade 2) during multi-pass rotary-die equal-channel angular pressing (RD-ECAP) and cold rolling (CR) were systematically investigated in this work, to achieve comprehensive property for faster industrial applications. The obtained results showed that
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Microstructure evolutions and mechanical properties of a commercially pure titanium (CP-Ti, grade 2) during multi-pass rotary-die equal-channel angular pressing (RD-ECAP) and cold rolling (CR) were systematically investigated in this work, to achieve comprehensive property for faster industrial applications. The obtained results showed that the grain size of CP-Ti decreased from 80 μm of as-received stage to 500 nm and 310 nm after four passes and eight passes of ECAP, respectively. Moreover, abundant dislocations were observed in ECAP samples. After subsequent cold rolling, the grain size of ECAPed CP-Ti was further refined to 120 nm and 90 nm, suggesting a good refining effect by combination of ECAP and CR. XRD (X-ray diffractometer) analysis and TEM (transmission electron microscope) observations indicated that the dislocation density increased remarkably after subsequent CR processing. Room temperature tensile tests showed that CP-Ti after ECAP + CR exhibited the best combination of strength and ductility, with ultimate tensile strength and fracture strain reaching 920 MPa and 20%. The high strength of this deformed CP-Ti originated mainly from refined grains and high density of dislocations, while the good ductility could be attributed to the improved homogeneity of UFG (ultra-fine grained) microstructure. Thus, a high strength and ductility ultra-fine grained CP-Ti was successfully prepared via ECAP plus CR. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Study in Wire Feedability-Related Properties of Al-5Mg Solid Wire Electrodes Bearing Zr for High-Speed Train
Metals 2017, 7(12), 520; doi:10.3390/met7120520
Received: 24 September 2017 / Revised: 19 November 2017 / Accepted: 20 November 2017 / Published: 23 November 2017
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Abstract
This work offers an analysis of the wire feedability-related properties of Al-5Mg solid wire electrodes bearing Zr. Effects of Zr content on microstructures and mechanical properties of the Al-5Mg alloys were studied. Experimental results have demonstrated that α-Al dendrites of the as-cast Al-5Mg
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This work offers an analysis of the wire feedability-related properties of Al-5Mg solid wire electrodes bearing Zr. Effects of Zr content on microstructures and mechanical properties of the Al-5Mg alloys were studied. Experimental results have demonstrated that α-Al dendrites of the as-cast Al-5Mg alloy are refined, and the tensile strength, microhardness and roughness of the 1.2 mm wire electrode are improved with an appropriate addition of Zr. In addition, the tensile strength and elongation of the welded joints welded using Al-5Mg wire electrodes bearing Zr reach the maximum value when 0.12% Zr is added into the wire alloy. However, when excess Zr is added, α-Al phases of the wire alloy and welded joint are coarsened, and the mechanical properties are deteriorated. Moreover, the structure and principle of a novel apparatus, which can enhance the feedability of the wire electrode, are introduced and the apparatus can achieve the rough and fine adjustments of cast and helix of the wire electrode. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Optimization of Thermo-Mechanical Processing for Forging of Newly Developed Creep-Resistant Magnesium Alloy ABaX633
Metals 2017, 7(11), 513; doi:10.3390/met7110513
Received: 28 October 2017 / Revised: 13 November 2017 / Accepted: 14 November 2017 / Published: 21 November 2017
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Abstract
The compressive strength and creep resistance of cast Mg-6Al-3Ba-3Ca (ABaX633) alloy has been measured in the temperature range of 25 to 250 °C, and compared with that of its predecessor ABaX422. The alloy is stronger and more creep-resistant than ABaX422, and exhibits only
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The compressive strength and creep resistance of cast Mg-6Al-3Ba-3Ca (ABaX633) alloy has been measured in the temperature range of 25 to 250 °C, and compared with that of its predecessor ABaX422. The alloy is stronger and more creep-resistant than ABaX422, and exhibits only a small decrease of yield stress with temperature. The higher strength of ABaX633 is attributed to a larger volume fraction of intermetallic particles (Al, Mg)2Ca and Mg21Al3Ba2 in its microstructure. Hot deformation mechanisms in ABaX633 have been characterized by developing a processing map in the temperature and strain rate ranges of 300 to 500 °C and 0.0003 to 10 s−1. The processing map exhibits two workability domains in the temperature and strain rate ranges of: (1) 380 to 475 °C and 0.0003 to 0.003 s−1, and (2) 480–500 °C and 0.003 to 0.5 s−1. The apparent activation energy values estimated in the above two domains (204 and 216 kJ/mol) are higher than that for lattice self-diffusion of Mg, which is attributed to the large back-stress that is caused by the intermetallic particles. Optimum condition for bulk working is 500 °C and 0.01 s−1 at which hot workability will be maximum. Flow instability is exhibited at lower temperatures and higher strain rates, as well as at higher temperatures and higher strain rates. The predictions of the processing map on the workability domains, as well as the instability regimes are fully validated by the forging of a rib-web (cup) shaped component under optimized conditions. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Microstructure and Fatigue Properties of AlZn6Mg0.8Zr Alloy Subjected to Low-Temperature Thermomechanical Processing
Metals 2017, 7(10), 448; doi:10.3390/met7100448
Received: 22 August 2017 / Revised: 10 October 2017 / Accepted: 12 October 2017 / Published: 21 October 2017
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Abstract
The paper presents results of the investigations on the effect of the low-temperature thermomechanical treatment on the microstructure of AlZn6Mg0.8Zr alloy (7003 alloy) and the relationships between microstructure and fatigue properties and fractography of fractured samples. Fatigue life has been determined in a
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The paper presents results of the investigations on the effect of the low-temperature thermomechanical treatment on the microstructure of AlZn6Mg0.8Zr alloy (7003 alloy) and the relationships between microstructure and fatigue properties and fractography of fractured samples. Fatigue life has been determined in a mechanical test at a simple state of loading under conditions of bending as well as torsion. The development of fatigue cracking has been described based on fractography investigations of the fractured samples making use of a scanning electron microscope (SEM). It was found that the factors determining the fatigue strength of the tested alloy are the microstructure as well as the type and size of the cyclic stresses. These factors determine the fractography of fatigue samples. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Characteristics of Resistance Spot Welded Ti6Al4V Titanium Alloy Sheets
Metals 2017, 7(10), 424; doi:10.3390/met7100424
Received: 4 September 2017 / Revised: 30 September 2017 / Accepted: 3 October 2017 / Published: 12 October 2017
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Abstract
Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding
[...] Read more.
Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding methods are required. In the present study, Ti6Al4V alloy sheets were joined using resistance spot welding, and the weld nugget formation, mechanical properties (including tensile strength and hardness), and microstructure features of the resistance spot-welded joints were analyzed and evaluated. The visible indentations on the weld nugget surfaces caused by the electrode force and the surface expulsion were severe due to the high welding current. The weld nugget width at the sheets’ faying surface was mainly affected by the welding current and welding time, and the welded joint height at weld nugget center was chiefly associated with electrode force. The maximum tensile load of welded joint was up to 14.3 kN in the pullout failure mode. The hardness of the weld nugget was the highest because of the coarse acicular α′ structure, and the hardness of the heat-affected zone increased in comparison to the base metal due to the transformation of the β phase to some fine acicular α′ phase. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Structural and Mechanical Evaluation of a Nanocrystalline Al–5 wt %Si Alloy Produced by Mechanical Alloying
Metals 2017, 7(9), 332; doi:10.3390/met7090332
Received: 7 July 2017 / Revised: 18 August 2017 / Accepted: 20 August 2017 / Published: 29 August 2017
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Abstract
High energy mechanical milling followed by hot-pressing consolidation has been used to produce nanostructured Al–5 wt %Si alloy. X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive X-ray detector (SEM-EDX), Vickers hardness, and compression measurements were used to examine the effect of
[...] Read more.
High energy mechanical milling followed by hot-pressing consolidation has been used to produce nanostructured Al–5 wt %Si alloy. X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive X-ray detector (SEM-EDX), Vickers hardness, and compression measurements were used to examine the effect of milling duration on microstructure and mechanical properties of the nanostructured consolidated alloys. Crystallite sizes and lattice strains were determined by X-ray peak broadening analysis using the Williamson-Hall (W-H) method. Increasing the milling time reduced the crystallite size, and the minimum crystallite size of about 33 nm was achieved for both consolidated and powdered samples after 50 h of milling. Based on the SEM-EDX observations, the best distribution of silicon into Al matrix was obtained after 20 h of milling and remained unchanged afterwards. Hardness of both consolidated and powder samples increased with milling time, which can be attributed to the reduction of crystallite size and the better distribution of silicon in the aluminum matrix. Similarly, increased milling time increased the yield and compressive strengths of consolidated samples. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Hot Deformation Behavior of a Spray-Deposited Al-8.31Zn-2.07Mg-2.46Cu-0.12Zr Alloy
Metals 2017, 7(8), 299; doi:10.3390/met7080299
Received: 20 June 2017 / Revised: 21 July 2017 / Accepted: 1 August 2017 / Published: 4 August 2017
Cited by 1 | PDF Full-text (7258 KB) | HTML Full-text | XML Full-text
Abstract
Metallic materials have a significant number of applications, among which Al alloys have drawn people’s attention due to their low density and high strength. High-strength Al-based alloys, such as 7XXX Al alloys, contain many alloying elements and with high concentration, whose microstructures present
[...] Read more.
Metallic materials have a significant number of applications, among which Al alloys have drawn people’s attention due to their low density and high strength. High-strength Al-based alloys, such as 7XXX Al alloys, contain many alloying elements and with high concentration, whose microstructures present casting voids, segregation, dendrites, etc. In this work, a spray deposition method was employed to fabricate an Al-8.31Zn-2.07Mg-2.46Cu-0.12Zr (wt %) alloy with fine structure. The hot deformation behavior of the studied alloy was investigated using a Gleeble 1500 thermal simulator and electron microscopes. The microstructure evolution, variation in the properties, and precipitation behavior were systematically investigated to explore a short process producing an alloy with high property values. The results revealed that the MgZn2 particles were detected from inside the grain and grain boundary, while some Al3Zr particles were inside the grain. An Arrhenius equation was employed to describe the relationship between the flow stress and the strain rate, and the established constitutive equation was that: ε ˙ = [ sinh ( 0.017 σ ) ] 4.049 exp [ 19.14 ( 129.9 / R T ) ] . An appropriate hot extrusion temperature was determined to be 460 °C. Hot deformation (460 °C by 60%) + age treatment (120 °C) was optimized to shorten the processing method for the as-spray-deposited alloy, after which considerable properties were approached. The high strength was mainly attributed to the grain boundary strengthening and the precipitation strengthening from the nanoscale MgZn2 and Al3Zr precipitates. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Effect of Fe-Content on the Mechanical Properties of Recycled Al Alloys during Hot Compression
Metals 2017, 7(7), 262; doi:10.3390/met7070262
Received: 10 June 2017 / Revised: 28 June 2017 / Accepted: 7 July 2017 / Published: 10 July 2017
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Abstract
It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two
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It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two Fe-containing Al alloys were carried out at elevated temperatures within a wide strain rate range from 0.01 s−1 to 10 s−1. The effect of Fe content on the peak stress of the stress vs. strain curves, strain rate sensitivity and activation energy for dynamic recrystallization are analyzed. Results show that the recycled Al alloy containing 0.5 wt % Fe exhibits higher peak stresses and larger activation energy than the recycled Al alloy containing 0.1 wt % Fe, which results from the fact that there are more dispersed AlMgFeSi and/or AlFeSi precipitates in the recycled Al alloy containing 0.5 wt % Fe as confirmed by SEM observation and energy spectrum analysis. It is also shown that the Fe content has little effect on the strain rate sensitivity of the recycled Al alloys. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Characteristics of the Dynamic Recrystallization Behavior of Ti-45Al-8.5Nb-0.2W-0.2B-0.3Y Alloy during High Temperature Deformation
Metals 2017, 7(7), 261; doi:10.3390/met7070261
Received: 7 June 2017 / Revised: 30 June 2017 / Accepted: 4 July 2017 / Published: 8 July 2017
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Abstract
The dynamic recrystallization (DRX) behavior of Ti-45Al-8.5Nb-0.2W-0.2B-0.3Y (at %) alloy has been investigated through hot compression tests. The tests were executed at a temperature range of 1000–1200 °C and a strain rate range of 0.001–1 s−1 under a true strain of 0.9.
[...] Read more.
The dynamic recrystallization (DRX) behavior of Ti-45Al-8.5Nb-0.2W-0.2B-0.3Y (at %) alloy has been investigated through hot compression tests. The tests were executed at a temperature range of 1000–1200 °C and a strain rate range of 0.001–1 s−1 under a true strain of 0.9. It was found that the α2 phase which is produced during heat treatment is reduced during hot compression due to thermo-mechanical coupling. The value of the activation energy is 506.38 KJ/mol. With the increase in deformation temperature and the decrease in strain rate, DRX is more likely to occur, as a result of sufficient time and energy for the DRX process. Furthermore, the volume fraction of high angle grain boundaries increases to 89.01% at a temperature of 1200 °C and the strain rate of 0.001 s−1, meaning completely dynamic recrystallization. In addition, DRX is related to the formation of twin boundaries. The volume fraction of twin boundaries rises to 16.93% at the same condition of completely dynamic recrystallization. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Effect of Anode Pulse-Width on the Microstructure and Wear Resistance of Microarc Oxidation Coatings
Metals 2017, 7(7), 243; doi:10.3390/met7070243
Received: 3 May 2017 / Revised: 27 June 2017 / Accepted: 27 June 2017 / Published: 30 June 2017
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Abstract
Microarc oxidation (MAO) coatings were prepared on 2024-T4 aluminum alloys using a pulsed bipolar power supply at different anode pulse-widths. After the MAO coatings were formed, the micropores and microcracks on the surface of the MAO coatings were filled with Fluorinated ethylene propylene
[...] Read more.
Microarc oxidation (MAO) coatings were prepared on 2024-T4 aluminum alloys using a pulsed bipolar power supply at different anode pulse-widths. After the MAO coatings were formed, the micropores and microcracks on the surface of the MAO coatings were filled with Fluorinated ethylene propylene (FEP) dispersion for preparing MAO self-lubricating composite coatings containing FEP. The effect of the anode pulse-width on the microstructure and wear resistance of the microarc oxidation coatings was investigated. The wear resistance of the microarc oxidation self-lubricating composite coatings was analyzed. The results revealed that the MAO self-lubricating composite coatings integrated the advantages of wear resistance of the MAO ceramic coatings and a low friction coefficient of FEP. Compared to the MAO coatings, the microarc oxidation self-lubricating composite coatings exhibited a lower friction coefficient and lower wear rates. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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Open AccessArticle Influence of Temperature-Dependent Properties of Aluminum Alloy on Evolution of Plastic Strain and Residual Stress during Quenching Process
Metals 2017, 7(6), 228; doi:10.3390/met7060228
Received: 31 March 2017 / Revised: 12 June 2017 / Accepted: 15 June 2017 / Published: 21 June 2017
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Abstract
To lessen quenching residual stresses in aluminum alloy components, theory analysis, quenching experiments, and numerical simulation were applied to investigate the influence of temperature-dependent material properties on the evolution of plastic strain and stress in the forged 2A14 aluminum alloy components during quenching
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To lessen quenching residual stresses in aluminum alloy components, theory analysis, quenching experiments, and numerical simulation were applied to investigate the influence of temperature-dependent material properties on the evolution of plastic strain and stress in the forged 2A14 aluminum alloy components during quenching process. The results show that the thermal expansion coefficients, yield strengths, and elastic moduli played key roles in determining the magnitude of plastic strains. To produce a certain plastic strain, the temperature difference increased with decreasing temperature. It means that the cooling rates at high temperatures play an important role in determining residual stresses. Only reducing the cooling rate at low temperatures does not reduce residual stresses. An optimized quenching process can minimize the residual stresses and guarantee superior mechanical properties. In the quenching process, the cooling rates were low at temperatures above 450 °C and were high at temperatures below 400 °C. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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