Additive Manufacturing of Al- and Mg-Based Light Metal Alloys

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Additive Manufacturing".

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 5883

Special Issue Editors


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Guest Editor
Department of Mechanical Engineering, Politecnico di Milano, Via Giuseppe La Masa 1, 20156 Milano, Italy
Interests: material science; metallurgy; additive manufacturing
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Mechanical Engineering, Politecnico di Milano, Via Giuseppe La Masa 1, 20156 Milano, Italy
Interests: material science; metallurgy; additive manufacturing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Light alloys and related composites are increasingly used in many industrial fields to obtain high-strength and light-weight structural components through additive manufacturing processing routes. The demand for increased performance and energy savings has pushed society towards a wider adoption of light materials, which are implemented through innovative design approaches, such as those based on topological optimization and the use of cellular structures.

This Special Issue of Metals focuses on the development of new light-alloy metals, especially those designed with optimal properties and that are easily processable through additive manufacturing routes such as laser powder bed fusion or directed energy deposition. Papers focused on specific design methodologies to further improve the efficiency of light-weight additively manufactured structures are also welcome.

While the focus of this Special Issue is aluminium alloys and related composites, other relevant metals and approaches to obtain light structures will be considered.

The papers presented in this Special Issue will provide an overview of recent technological advances and the industrial state of the art for light-metal additive manufacturing from the above described perspectives.

Prof. Dr. Maurizio Vedani
Prof. Dr. Riccardo Casati
Guest Editors

Manuscript Submission Information

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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
  • magnesium
  • metal matrix composites
  • alloy design
  • processing
  • thermal treatments

Published Papers (3 papers)

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Research

15 pages, 14027 KiB  
Article
Microstructural Evolution of a High-Strength Zr-Ti-Modified 2139 Aluminum Alloy for Laser Powder Bed Fusion
by Federico Larini, Riccardo Casati, Silvia Marola and Maurizio Vedani
Metals 2023, 13(5), 924; https://doi.org/10.3390/met13050924 - 10 May 2023
Cited by 4 | Viewed by 1675
Abstract
The demand for high-performance aluminum components drives research into the design of novel alloys that can be processed by laser-based additive manufacturing. In recent years, the addition of grain refiners proved to be an effective strategy to reduce the hot-cracking of high-strength Al [...] Read more.
The demand for high-performance aluminum components drives research into the design of novel alloys that can be processed by laser-based additive manufacturing. In recent years, the addition of grain refiners proved to be an effective strategy to reduce the hot-cracking of high-strength Al alloys. In this study, the solidification and aging behavior of an Al2139 alloy doped with additions of Zr and Ti for L-PBF was investigated. These elements favored the formation of a fine-grained structure free of cracks. The formation of Al3(Zr,Ti) inoculants was predicted by Scheil simulations and observed as cuboidal particles in the center of α-Al grains. The microstructure of the as-built material featured fine and fully equiaxed grains, which appeared comparatively finer at the edge (300–600 nm) and coarser (0.8–2.0 μm) at the center of the molten pools. In both cases, there was evidence of Cu and Mg micro-segregations at the grain boundaries. The microhardness of 109.7 HV0.5 in the as-built state was increased to 186.1 HV0.5 after optimized T4 heat treatment, responsible for the precipitation of many rod-shaped Zr- and Ti-based second phases and quasi-spherical Cu-, Mn-, and Fe-rich particles. Prolonged exposure carried out to simulate high-temperature service caused a drop in microhardness and marked modification of the microstructure, evidenced by the rearrangement and subsequent spheroidization of Cu- and Mg-rich particles at the grain boundaries. Full article
(This article belongs to the Special Issue Additive Manufacturing of Al- and Mg-Based Light Metal Alloys)
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16 pages, 11607 KiB  
Article
LPBF-Formed 2024Al Alloys: Process, Microstructure, Properties, and Thermal Cracking Behavior
by Sen Yao, Jiajian Wang, Min Li, Zhen Chen, Bingheng Lu, Song Shen and Yao Li
Metals 2023, 13(2), 268; https://doi.org/10.3390/met13020268 - 29 Jan 2023
Cited by 1 | Viewed by 1592
Abstract
2024Al is an Al-Cu-Mg series heat-treatable aluminum alloy with high strength and excellent damage resistance. To obtain a high-performance target component of LPBF-formed 2024Al, the effect of process parameters on density, microstructure, and performance is systematically investigated and the thermal cracking phenomenon is [...] Read more.
2024Al is an Al-Cu-Mg series heat-treatable aluminum alloy with high strength and excellent damage resistance. To obtain a high-performance target component of LPBF-formed 2024Al, the effect of process parameters on density, microstructure, and performance is systematically investigated and the thermal cracking phenomenon is analyzed in detail. The results reveal that the optimization of process parameters can suppress the cracks generated during the LPBF forming of 2024Al to a certain extent. When the laser energy density is 741 J/mm3, the maximum density reaches 99.77%, whereas the tensile strength and elongation reach 330 ± 7 MPa and 9 ± 0.6%, respectively. Owing to the high Cu and Mg contents in 2024Al, the transverse strain rate of columnar grains during LPBF forming is easily higher than the sum of the transverse expansion rate of grains and the liquid phase filling rate at grain boundaries, resulting in strong thermal crack sensitivity. In addition, an extremely high cooling rate (−108 K/s) and heat input during LPBF forming reduce the liquid phase filling rate at grain boundaries to further aggravate the thermal cracking tendency. The current study provides experimental guidance for the preparation of high-quality, crack-less, or even crack-free 2024Al alloys. Full article
(This article belongs to the Special Issue Additive Manufacturing of Al- and Mg-Based Light Metal Alloys)
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20 pages, 8550 KiB  
Article
The Effect of Heat Accumulation on the Local Grain Structure in Laser-Directed Energy Deposition of Aluminium
by Christian Hagenlocher, Patrick O’Toole, Wei Xu, Milan Brandt, Mark Easton and Andrey Molotnikov
Metals 2022, 12(10), 1601; https://doi.org/10.3390/met12101601 - 25 Sep 2022
Cited by 6 | Viewed by 2114
Abstract
The energy used to melt the material at each layer during laser-directed energy deposition (L-DED) accumulates in the solidified layers upon layer deposition and leads to an increase in the temperature of the part with an increasing number of layers. This heat accumulation [...] Read more.
The energy used to melt the material at each layer during laser-directed energy deposition (L-DED) accumulates in the solidified layers upon layer deposition and leads to an increase in the temperature of the part with an increasing number of layers. This heat accumulation can lead to inhomogeneous solidification conditions, increasing residual stresses and potentially anisotropic mechanical properties due to columnar grain structures. In this work, infrared imaging is applied during the directed energy deposition process to capture the evolution of the temperature field in high spatial and temporal evolutions. Image processing algorithms determined the solidification rate and the temperature gradient in the spatial and temporal evolutions and evidenced their change with the proceeding deposition process. Metallographic analysis proves that these changes significantly affect the local grain structure of the L-DED fabricated parts. The study provides comprehensive quantitative measurements of the change in the solidification variables in local and temporal resolutions. The comprehensive comparison of different parameter combinations reveals that applied power, and especially the frequency of the consecutive deposition of the individual layers, are the key parameters to adjusting heat accumulation. These findings provide a methodology for optimising L-DED manufacturing processes and tailoring the local microstructure development by controlling heat accumulation. Full article
(This article belongs to the Special Issue Additive Manufacturing of Al- and Mg-Based Light Metal Alloys)
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