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17 pages, 3906 KB

Open AccessArticle

Understanding the Impact of Cooling Systems on Bulk Additive Friction Stir Deposition of Aluminum

by Luk Dean, Brian Gierk and Yuri Hovanski

Metals 2026, 16(4), 382; https://doi.org/10.3390/met16040382 - 31 Mar 2026

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This work presents an investigation of two cooling systems used in additive friction stir depositions (AFSD) and the related effect on process temperature, feed material, and life of processing equipment. A new AFSD cooling system, Mazak MegaStir Liquid-cooled Toolholder (LCTH), was integrated onto [...] Read more.

This work presents an investigation of two cooling systems used in additive friction stir depositions (AFSD) and the related effect on process temperature, feed material, and life of processing equipment. A new AFSD cooling system, Mazak MegaStir Liquid-cooled Toolholder (LCTH), was integrated onto MELD Manufacturing AFSD machines using both continuous and discrete material feeding systems. The LCTH is compared to the original MELD cooling system to understand how process temperatures are controlled by the cooling systems, how feed material interacts with the process under different cooling conditions, and how well the cooling systems protect the equipment. It is shown that spindle revolution rate impacts the temperature experienced by the bearings more greatly than the utilization of cooling. The attempt of three large volume depositions demonstrates the necessity of a cooling system utilization for AFSD. Additionally, four configurations of tool and cooling system are analyzed to understand parameters that affect depositions temperature and the thermal effect on feed material. Configurations with short working face to cooling distances show ~40 K cooler deposition temperatures and configurations with the new LCTH deposited ~9 K cooler than those deposited with the original MELD cooling system. Microhardness analysis on feed material revealed the varying efficacy of each cooling configuration’s ability to enable bulk deposition. The influence of feed system on process temperatures is also presented with a comparison of discrete and continuous feed system depositions. Full article

(This article belongs to the Special Issue Processing, Microstructure and Properties of Aluminium Alloys)

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13 pages, 2640 KB

Open AccessArticle

Influence of the Final Annealing Temperature on Al-Fe-Si Alloy Foil Microstructure and Properties

by Xiuda Zhu, Changle Xiao, Xiubin Wang, Xiaohu Chen, Hongyan Wu and Wei Chen

Metals 2026, 16(4), 368; https://doi.org/10.3390/met16040368 - 27 Mar 2026

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Abstract

This study systematically investigates the effects of the final annealing temperature on the microstructural evolution and mechanical properties of an Al-Fe-Si alloy aluminum foil. Scanning electron microscopy (SEM) characterization and tensile tests are employed for analysis. As the annealing temperature is elevated from [...] Read more.

This study systematically investigates the effects of the final annealing temperature on the microstructural evolution and mechanical properties of an Al-Fe-Si alloy aluminum foil. Scanning electron microscopy (SEM) characterization and tensile tests are employed for analysis. As the annealing temperature is elevated from 240 °C to 360 °C, the average grain size increases monotonically from 5.2 μm to 9.6 μm. Continuous recrystallization is identified as the predominant grain growth mechanism. Tensile deformation exhibits the homogeneous plastic behavior without localized necking. The tensile strength decreases significantly in the range of 240–300 °C and subsequently undergoes a recovery stage at 300–360 °C. Significant elongation anisotropy is observed. The maximum elongation reaches 30–34% in the 45° direction, relative to the rolling direction (RD), which is approximately 1.5 times that along the RD (0°). Comparative analysis of the anisotropy indices demonstrates that the aluminum foil annealed at 240 °C achieves the minimal tensile strength anisotropy (13.0 MPa) and elongation anisotropy (−4.2%). This indicates an optimal comprehensive mechanical performance. These findings provide a theoretical rationale for the industrial optimization of the annealing processes for Al-Fe-Si alloy foils. They are particularly valuable for balancing microstructural regulation and mechanical property enhancement in lithium-ion battery soft-packaging applications. Full article

(This article belongs to the Special Issue Processing, Microstructure and Properties of Aluminium Alloys)

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15 pages, 4321 KB

Open AccessArticle

Effect of Pre-Deformation on Microstructure and Mechanical Properties of a Mg-Rich High-Cu Al-Mg-Si-Cu Alloy

by Lipeng Ding, Yuqi Yang, Yue Zheng, Tengqiang Yin, Huilan Huang and Yaoyao Weng

Metals 2026, 16(4), 366; https://doi.org/10.3390/met16040366 - 26 Mar 2026

Cited by 1 | Viewed by 380

Abstract

The influence of pre-deformation on the microstructure and mechanical properties of a Mg-rich high-Cu Al-Mg-Si-Cu alloy was systematically investigated by hardness measurement, tensile test, and atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). With the increase in pre-deformation strain (0–10%), the [...] Read more.

The influence of pre-deformation on the microstructure and mechanical properties of a Mg-rich high-Cu Al-Mg-Si-Cu alloy was systematically investigated by hardness measurement, tensile test, and atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). With the increase in pre-deformation strain (0–10%), the hardness and strength of the alloy after PB hardening increased progressively, accompanied by a continuous reduction in tensile elongation. Notably, increasing pre-deformation strain from 2% to 10% did not bring a significant enhancement in bake hardening response, despite the gradual improvement in the strain hardening capability of the alloy. An optimal pre-deformation strain of 5% is identified, which enabled the alloy to achieve a superior and industrially feasible combination of strength and ductility, balancing practical forming demand (T4 temper) and service performance (PB state). Pre-deformation can significantly affect the morphology and atomic structure of precipitates for the alloy. Dislocations introduced by pre-deformation acted as heterogeneous nucleation sites, inducing the formation of elongated and string-like precipitates along dislocation lines. A distinct Cu segregation behavior was observed in the pre-deformed alloy with the majority of Cu atoms segregated at the precipitate/α-Al interface, which was in sharp contrast to their dominant distribution within the precipitate interior in the non-pre-deformed alloy. These findings provide new insights into deformation-assisted precipitation regulation in Mg-rich high-Cu Al-Mg-Si-Cu alloys and offer practical guidance for optimizing the strength–ductility synergy of such alloys for automotive lightweight manufacturing applications. Full article

(This article belongs to the Special Issue Processing, Microstructure and Properties of Aluminium Alloys)

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18 pages, 16109 KB

Open AccessArticle

Microstructural Evolution in the Stir Zone of a Friction-Stir-Processed Microalloyed Al-Mn-Cu Alloy

by Franc Zupanič, Pamela Marcela Pineda Dominguez, Yan Lu, Torben Boll, Rafal Dunin-Borkowski, Lara Hočuršćak, Evelin Fisslthaler, Damjan Klobčar and Tonica Bončina

Metals 2026, 16(3), 358; https://doi.org/10.3390/met16030358 - 23 Mar 2026

Viewed by 454

Abstract

The study investigates the microstructure evolution in the stir zone produced by the friction stir processing (FSP) of a heat-treated microalloyed Al-Mn-Cu alloy in the area subjected to the highest temperature, strain, and strain rate. The samples were studied using electron microscopy and [...] Read more.

The study investigates the microstructure evolution in the stir zone produced by the friction stir processing (FSP) of a heat-treated microalloyed Al-Mn-Cu alloy in the area subjected to the highest temperature, strain, and strain rate. The samples were studied using electron microscopy and atom probe tomography (APT) to obtain structural and chemical information from the macro to the nano scale. FSP refines the dendritic Al-rich solid solution grains through dynamic recrystallisation in the range of a few micrometres. The primary intermetallic phases were dispersed to the particles in the 0.5–3 µm range and transformed mainly into a more stable τ₁-Al₂₉Mn₆Cu₄ phase. The fraction of dispersed particles after FSP increased due to the precipitation from the solid solution during cooling. The nanoscale quasicrystalline precipitates in the matrix, formed upon heat treatment, dissolved entirely during FSP, while the strong coarsening of the L1₂ precipitates occurred due to high temperatures in the stir zone. After FSP, the hardness of the stir zone was nearly identical for specimens in the as-cast and heat-treated conditions. Full article

(This article belongs to the Special Issue Processing, Microstructure and Properties of Aluminium Alloys)

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17 pages, 2730 KB

Open AccessArticle

Effect of Artificial Aging Conditions on Mechanical Properties of EN AW 6056 Aluminum Alloy

by Gizem Ay, Mehmet Okan Görtan and Fatih Çağırankaya

Metals 2026, 16(1), 88; https://doi.org/10.3390/met16010088 - 13 Jan 2026

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Abstract

The 6xxx series aluminum alloys are preferred in many industrial applications because they can achieve relatively high strength levels through heat treatment. It is known that, as in the case of the EN AW 6056 alloy, the addition of small amounts of copper [...] Read more.

The 6xxx series aluminum alloys are preferred in many industrial applications because they can achieve relatively high strength levels through heat treatment. It is known that, as in the case of the EN AW 6056 alloy, the addition of small amounts of copper to materials in this series can further enhance their mechanical properties. In the current study, the effect of artificial aging conditions on the mechanical properties of EN AW 6056 aluminum alloy has been investigated. The ratio of Mg to Si and Cu content of the alloy were 0.939 and 0.92, respectively. The aging process was conducted at temperatures of 170, 180, and 190 °C, with corresponding aging durations of 1, 2, 3, 4, 6, 8, 12, 15, 18, 21, and 24 h. The maximum hardness was obtained in samples aged at 170 °C for 12 h, corresponding to the transition to over-aging condition. In contrast, the highest tensile strength was achieved in samples aged at 190 °C for 4 h, representing the peak-aged condition. Transmission electron microscopy (TEM) analyses revealed distinct microstructural characteristics for the peak-aged and transition to over-aging conditions. In the peak-aged state, needle-shaped β″ precipitates, lath-like Q′ phases, and L phases with narrow rectangular cross-sections were observed. In contrast, lath-like L precipitates were absent in the transition to over-aging condition. Full article

(This article belongs to the Special Issue Processing, Microstructure and Properties of Aluminium Alloys)

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19 pages, 6268 KB

Open AccessArticle

Research on Arc Characteristics and Microstructure of 6061 Aluminum Alloy Multi-Pulse Composite Arc Welding

by Guangshun Zhang, Xin Ye, Fang Li, Yonggang Du, Guangcai Chang and Peng Xia

Metals 2025, 15(12), 1294; https://doi.org/10.3390/met15121294 - 25 Nov 2025

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Abstract

To mitigate welding defects and optimize the microstructure of aluminum alloys, this study introduces a multi-pulse hybrid arc welding process. A comparative investigation was carried out between this novel process (AC/DC composite 1 kHz pulsed welding) and conventional methods (AC pulsed, AC/DC pulsed) [...] Read more.

To mitigate welding defects and optimize the microstructure of aluminum alloys, this study introduces a multi-pulse hybrid arc welding process. A comparative investigation was carried out between this novel process (AC/DC composite 1 kHz pulsed welding) and conventional methods (AC pulsed, AC/DC pulsed) during wire-fed overlay welding of 6061 aluminum alloy. Analyses were conducted on electrical signals, arc morphology, joint microstructure, and hardness. The results indicate that the AC/DC hybrid 1 kHz pulsed process combines the characteristics of both AC and DC pulsed signals with full-cross-section frequency pulse superposition, thereby optimizing arc welding process control. The frequency pulses induce a magnetoelectric effect, leading to significant arc constriction, which enhances arc energy density and arc pressure. This intensifies the fluid flow in the molten pool and accelerates cooling, thereby suppressing the growth of columnar grains and promoting the formation of fine equiaxed grains and an increased proportion of high-angle grain boundaries. Meanwhile, this process effectively reduces the number, area fraction, and overall porosity, and facilitates the distribution of a large amount of Al–Si eutectic structure along grain boundaries, enhancing the impediment to dislocation motion. The microstructural optimization significantly improves the hardness at the weld center to 73.1 HV, leading to enhanced mechanical properties. Full article

(This article belongs to the Special Issue Processing, Microstructure and Properties of Aluminium Alloys)

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22 pages, 9679 KB

Open AccessArticle

Impact of Multiple-Laser Processing on the Low-Cycle Fatigue Behaviour of Laser-Powder Bed Fused AlSi10Mg Alloy

by Arun Prasanth Nagalingam, Erkan Bugra Tureyen, Abdul Haque, Adrian Sharman, Ozgur Poyraz, Evren Yasa and James Hughes

Metals 2025, 15(7), 807; https://doi.org/10.3390/met15070807 - 18 Jul 2025

Cited by 1 | Viewed by 1449

Abstract

Multi-laser processing is increasingly adopted in laser powder bed fusion (L-PBF) to improve productivity and enable the fabrication of larger components, but its impact on part quality and performance remains a critical concern. This study investigates the microstructure, tensile properties, and fatigue performance [...] Read more.

Multi-laser processing is increasingly adopted in laser powder bed fusion (L-PBF) to improve productivity and enable the fabrication of larger components, but its impact on part quality and performance remains a critical concern. This study investigates the microstructure, tensile properties, and fatigue performance of components fabricated by L-PBF using single- and multiple-laser configurations. Both strategies were evaluated under varying layer thicknesses and gas flow conditions with optimized process parameters. Microstructural analysis revealed defects such as lack-of-fusion, porosity and microcracks in multiple-laser builds with reduced gas flow. However, the density and microhardness results showed negligible differences between single and multiple-laser builds. Tensile testing indicated that single-laser builds exhibited superior strength and ductility, whereas multiple-laser builds demonstrated reduced performance due to localized defects such as lack-of-fusion and microcracks. Low-cycle fatigue testing results showed that optimized multiple-laser strategies could achieve performance comparable to that of single-laser builds while improving productivity. The results also revealed that the gas flow becomes more pronounced with multiple-laser processing, where more spatter is generated due to the interactions of the lasers in a small scan area, and that reduced gas flow leads to fatigue degradation due to increased defect density. The results from this study clearly highlight the importance of gas flow, laser overlap, border optimization, and defect mitigation strategies in producing multiple-laser produced components with mechanical properties and fatigue performance comparable to those of single-laser produced L-PBF components. Full article

(This article belongs to the Special Issue Processing, Microstructure and Properties of Aluminium Alloys)

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15 pages, 2065 KB

Open AccessArticle

Effects of Fin Height, Base Thickness, Blackening, Emissivity and Thermal Conductivity on Heat Dissipation of Die-Cast Aluminum Alloy Heat Sink

by Hiroshi Fuse, Shusuke Oe and Toshio Haga

Metals 2025, 15(7), 696; https://doi.org/10.3390/met15070696 - 23 Jun 2025

Cited by 6 | Viewed by 2015

Abstract

The effects of fin height, base thickness, blackening, emissivity and thermal conductivity on the heat dissipation for die-cast aluminum alloy heat sinks were investigated comprehensively. The thermal conductivity and emissivity vary depending on the aluminum alloy. It was clarified whether correlations between the [...] Read more.

The effects of fin height, base thickness, blackening, emissivity and thermal conductivity on the heat dissipation for die-cast aluminum alloy heat sinks were investigated comprehensively. The thermal conductivity and emissivity vary depending on the aluminum alloy. It was clarified whether correlations between the influences of these factors exist. Three aluminum alloys with different thermal conductivities and emissivities were used in this study. Four-finned heat sinks were produced by die casting. Four fin heights and three base thicknesses were tested. In the as-cast (non-blackened) heat sinks, the emissivity had a greater effect on the heat dissipation than the thermal conductivity did. In blackened heat sinks, the heat dissipation increased as the thermal conductivity increased. For both the as-cast and blackened heat sinks, the heat dissipation increased as both the fin height and base thickness increased. Correlations between these influencing factors were also investigated. The blackened heat sink made from aluminum alloy with larger thermal conductivity showed the best heat dissipation performance. Full article

(This article belongs to the Special Issue Processing, Microstructure and Properties of Aluminium Alloys)

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