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2 pages, 163 KiB

Open AccessEditorial

Special Issue: “Advanced Light Metal and Alloys: Preparation, Characterization, and Applications”

by Pingping Liu

Materials 2023, 16(24), 7617; https://doi.org/10.3390/ma16247617 - 12 Dec 2023

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Abstract

This Special Issue presents fundamental and applied research in advanced light metal and alloys [...] Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

Research

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12 pages, 10413 KiB

Open AccessFeature PaperArticle

Characterization of a Unique Nuragic Bronze Navicella with a Combination of X-ray Fluorescence Spectrometry and Monte Carlo Simulation

by Marta Porcaro, Sergio Lins, Anna Depalmas, Rosario Maria Anzalone, Roberta Iannaccone and Antonio Brunetti

Materials 2023, 16(23), 7345; https://doi.org/10.3390/ma16237345 - 25 Nov 2023

Cited by 3 | Viewed by 1344

Abstract

This paper describes the results obtained from an archaeometric study of a bronze Nuragic small boat model (Sardinia, Italy) dating from the Early Iron Age (presumably 9th–7th centuries BC). The artifact comes from an unknown location in Sardinia and is one of the [...] Read more.

This paper describes the results obtained from an archaeometric study of a bronze Nuragic small boat model (Sardinia, Italy) dating from the Early Iron Age (presumably 9th–7th centuries BC). The artifact comes from an unknown location in Sardinia and is one of the objects that came to the Museum of Turin in the 19th century. This model is of particular interest as it is a unique Nuragic boat model containing a human figure among its decorations. The artifact is kept in the collection of the Royal Museum of Turin (Italy) and is a typical example of Sardinian manufacture from the Early Iron Age. This study was carried out using a combination of non-invasive techniques with energy dispersive X-ray fluorescence spectrometry (ED-XRF) integrated with Monte Carlo (MC) simulations and Raman spectroscopy, which allowed the characterization of the alloy of the artifact. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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10 pages, 1110 KiB

Open AccessCommunication

Effect of Alloying Elements on the Short-Range Orders and Atomic Diffusion Behavior of Liquid Al−9Si Cast Alloys

by Xunming Zhu, Dan Liu, Jian Wang, Candong Chen, Xinxin Li, Li Wang and Mingxu Wang

Materials 2023, 16(20), 6768; https://doi.org/10.3390/ma16206768 - 19 Oct 2023

Cited by 2 | Viewed by 1327

Abstract

To investigate the influence of alloying elements (Zn, Mg, and Cu) on the structural and dynamical properties of liquid Al−9Si alloy, we conducted ab initio molecular dynamics (AIMD) simulations. Our results indicate that the structure of Al−Si−M ternary alloys is determined with a [...] Read more.

To investigate the influence of alloying elements (Zn, Mg, and Cu) on the structural and dynamical properties of liquid Al−9Si alloy, we conducted ab initio molecular dynamics (AIMD) simulations. Our results indicate that the structure of Al−Si−M ternary alloys is determined with a combination of atomic radii and mixing enthalpy, while the dynamic properties are primarily influenced by electronic structure of the alloying elements. Specifically, the addition of Cu promotes the formation of Al−Cu short-range order (SRO), while Zn has a higher propensity for Zn−Zn SRO. The Al−Cu SRO in liquid alloy may serve as the precursor for the Al₂Cu reinforcing phase in Al−Si−Cu alloys. Upon the addition of Mg, a greater number of relatively stable perfect and distorted icosahedral structures, as well as hcp and bcc ordered structures with lower energies, are observed. Additionally, the presence of Mg leads to a reduction in the atomic diffusion rates of Al and Si, while Cu and Zn exhibit complex diffusion behavior influenced by the presence of Si atoms. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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17 pages, 5418 KiB

Open AccessArticle

Study of the Mechanical Properties and Microstructure of Spiral Tubes and Actuators for Controlled Extension Fabricated with Beryllium Bronze Strips

by Ruilong Lu, Jingtao Han, Zhanhua Li, Congfa Zhang, Jiawei Liu, Cheng Liu, Zhenqian Lang and Xiaoyan Ma

Materials 2023, 16(20), 6719; https://doi.org/10.3390/ma16206719 - 17 Oct 2023

Cited by 3 | Viewed by 1310

Abstract

QBe2.0 strips were used to fabricate spiral tubes and actuators for controlled extension (STACERs) through the winding and stabilization method, which is a novel technique for obtaining STACERs. The raw strips and the STACERs were investigated using tensile tests and SEM for the [...] Read more.

QBe2.0 strips were used to fabricate spiral tubes and actuators for controlled extension (STACERs) through the winding and stabilization method, which is a novel technique for obtaining STACERs. The raw strips and the STACERs were investigated using tensile tests and SEM for the mechanical properties and fractography observation, employing specialized test equipment for service performance, and via XRD, EBSD, and TEM were used to test the residual stress and microstructure evolution. The tensile strength/elongation for raw strips was 485.8 MPa/60%, while for STACERs, tensile strength increased by 834.67 MPa to 646 MPa, and the elongation rate decreased by 12% to 19.3%. The fractography showed that the fracture mode was ductile. The service performance tests indicated that STACERs obtained under 320 °C had a higher driving force, good pointing accuracy, and high bending stiffness, while the residual stress of raw strips was τ_xy = −6 MPa; for STACERs obtained between 290 °C and 350 °C, τ_xy decreased from −5 MPa to −74 MPa, then increased from −74 MPa to 21 MPa, and the optimum fabricating parameter was 320 °C + 2 h. The EBSD results showed that LABs and HABs for raw strips and STACERs at 320 °C + 2 h accounted for 3–97% and 24.5–75.5%, the grain sizes were 7.07 μm and 3.67 μm, and the twin fraction decreased from 57.3% to 31.8%, respectively. The KAM and Schmid factor maps indicated that the STACER was prone to recovering and recrystallizing. Coupled with the EBSD results, the TEM results indicated that the strengthening mechanism for raw strips is twinning strengthening, while that for STACER is grain-refining strengthening with a precipitation of the γ″ phase. It is a meaningful novelty that the relationship between the macro properties and microstructure has been elucidated. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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13 pages, 7400 KiB

Open AccessEditor’s ChoiceArticle

Thermodynamic and Microstructural Analysis of Lead-Free Machining Aluminium Alloys with Indium and Bismuth Additions

by Simon Rečnik, Maja Vončina, Aleš Nagode and Jožef Medved

Materials 2023, 16(18), 6241; https://doi.org/10.3390/ma16186241 - 16 Sep 2023

Cited by 2 | Viewed by 1806

Abstract

The present study comprises an investigation involving thermodynamic analysis, microstructural characterisation, and a comparative examination of the solidification sequence in two different aluminium alloys: EN AW 6026 and EN AW 1370. These alloys were modified through the addition of pure indium and a [...] Read more.

The present study comprises an investigation involving thermodynamic analysis, microstructural characterisation, and a comparative examination of the solidification sequence in two different aluminium alloys: EN AW 6026 and EN AW 1370. These alloys were modified through the addition of pure indium and a master alloy consisting of indium and bismuth. The aim of this experiment was to evaluate the potential suitability of indium, either alone or in combination with bismuth, as a substitute for toxic lead in free-machining aluminium alloys. Thermodynamic analysis was carried out using Thermo-Calc TCAL-6 software, supplemented by differential scanning calorimetry (DSC) experiments. The microstructure of these modified alloys was characterised using SEM–EDS analysis. The results provide valuable insights into the formation of different phases and eutectics within the alloys studied. The results represent an important contribution to the development of innovative, lead-free aluminium alloys suitable for machining processes, especially for use in automatic CNC cutting machines. One of the most important findings of this research is the promising suitability of indium as a viable alternative to lead. This potential stems from indium’s ability to avoid interactions with other alloying elements and its tendency to solidify as homogeneously distributed particles with a low melting point. In contrast, the addition of bismuth does not improve the machinability of magnesium-containing aluminium alloys. This is primarily due to their interaction, which leads to the formation of the Mg₃Bi₂ phase, which solidifies as a eutectic with a high melting point. Consequently, the presence of bismuth appears to have a detrimental effect on the machining properties of the alloy when magnesium is present in the composition. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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17 pages, 12968 KiB

Open AccessArticle

Microstructure Evolution of the Ti-46Al-8Nb-2.5V Alloy during Hot Compression and Subsequent Annealing at 900 °C

by Shouzhen Cao, Zongze Li, Jiafei Pu, Jianchao Han, Qi Dong and Mingdong Zhu

Materials 2023, 16(18), 6176; https://doi.org/10.3390/ma16186176 - 12 Sep 2023

Cited by 1 | Viewed by 1391

Abstract

TiAl alloys are high-temperature structural materials with excellent comprehensive properties, and their ideal service temperature range is about 700–950 °C. High-Nb containing the Ti-46Al-8Nb-2.5V alloy was subjected to hot compression and subsequent annealing at 900 °C. During hot compression, work-hardening and strain-softening occurred. [...] Read more.

TiAl alloys are high-temperature structural materials with excellent comprehensive properties, and their ideal service temperature range is about 700–950 °C. High-Nb containing the Ti-46Al-8Nb-2.5V alloy was subjected to hot compression and subsequent annealing at 900 °C. During hot compression, work-hardening and strain-softening occurred. The peak stresses during compression are positively correlated with the compressive strain rates and negatively correlated with the compression temperatures. The α₂ phase exhibited a typical (0001)α₂ basal plane texture after hot compression, while the β₀ and γ phases did not show a typical strong texture. Subsequent annealing at 900 °C of the hot-compressed samples resulted in significant phase transformations, specifically the α₂ → γ and β₀ → γ phase transformations. After 30 min of annealing, the volume fraction of the α₂ phase decreased from 39.0% to 4.6%. The microstructure characteristics and phase fraction after 60 min of annealing were similar to those after 30 min. According to the calculation of Miller indexes and texture evolution during annealing, the α₂ → γ phase transformation did not follow the Blackburn orientation relationship. Multiple crystal-oriented α₂ phases with nanoscale widths (20~100 nm) precipitate within the γ phase during the annealing process, which means the occurrence of γ → α₂ phase transformation. Still, the γ → α₂ phase transformation follows the Blackburn orientation relationship. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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12 pages, 6944 KiB

Open AccessArticle

Effect of Cold Pressing Deformation on Microstructure and Residual Stress of 7050 Aluminum Alloy Die Forgings

by Huiqu Li, Liang Wang, Weiwei He, Liqiang Cheng, Junzhou Chen and Linna Yi

Materials 2023, 16(14), 5129; https://doi.org/10.3390/ma16145129 - 20 Jul 2023

Cited by 1 | Viewed by 1590

Abstract

Large-scale, high-strength aluminum alloy forgings are essential components in the aerospace industry, with benefits including increasing strength and decreasing weight. Accurate shape-property control is the secret to forging quality. This study uses the alloy 7050 to experimentally evaluate the parametric influence of cold [...] Read more.

Large-scale, high-strength aluminum alloy forgings are essential components in the aerospace industry, with benefits including increasing strength and decreasing weight. Accurate shape-property control is the secret to forging quality. This study uses the alloy 7050 to experimentally evaluate the parametric influence of cold compression on residual stress and mechanical characteristics. The evolutions of mechanical properties, microstructure and residual stress are theoretically studied using various cold compression strains from 1% to 5% on an equivalent part, of which the results are further applied on a complicated rib-structured die forging. It is demonstrated that increasing the compression strain reduces the tensile strength of the material, but has little impact on conductivity and fracture toughness. According to the TEM results, compression also encourages the precipitation and growth of precipitated phases, particularly in positions with high dislocation densities after aging. Cold compression significantly reduces residual stress; nevertheless, as compression strain increases, residual stress first decreases and then increases. With the use of rib-structured forging, it is observed that the compression strain for 7050 aluminum alloy ranges from 2% to 4%, and the combined pressing method of the rib and web improves the uniformity of residual stress. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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15 pages, 23434 KiB

Open AccessArticle

Effect of Initial Orientation on the Anisotropy in Microstructure and Mechanical Properties of 2195 Al–Li Alloy Sheet during Hot Tensile Deformation

by Jian Ning, Jiangkai Liang, Xinyu Hu, Xianggang Ruan and Zhubin He

Materials 2023, 16(14), 5012; https://doi.org/10.3390/ma16145012 - 15 Jul 2023

Cited by 4 | Viewed by 1275

Abstract

The 2195 Al–Li alloy, as one of the representative third-generation Al–Li alloys, has extensive applications in lightweight aerospace structures. In this paper, the anisotropy in mechanical properties and microstructure evolution of 2195 Al–Li alloy sheets were investigated under a strain rate of 0.01, [...] Read more.

The 2195 Al–Li alloy, as one of the representative third-generation Al–Li alloys, has extensive applications in lightweight aerospace structures. In this paper, the anisotropy in mechanical properties and microstructure evolution of 2195 Al–Li alloy sheets were investigated under a strain rate of 0.01, 0.1, 1 s⁻¹ and a temperature of 440 and 500 °C. Experimental results showed that the hot tensile properties of the 2195 Al–Li alloy sheet exhibited a strong dependence on loading directions. The peak stress (PS) and elongation (EL) along the rolling direction (RD) were larger than the transverse direction (TD). For the tests carried out at 440 °C-1 s⁻¹, the PS values of the sheets stretched along the RD and TD are 142.9 MPa and 110.2 MPa, respectively. And, most of the PS anisotropy values are larger than 15%. The anisotropy in EL is less significant than in PS. All the differences are about 10%. Moreover, dimples in the samples stretched along RD were more and deeper than those along TD at 440 °C. The fracture morphology along RD and TD were similar, and both were cleavage fractures at 500 °C. Particularly, the fractions of high angle grain boundaries (HAGBs) along TD were all about 5% larger than those of RD. And, there were more small-sized continuous dynamic recrystallization (CDRX) grains inside the initial grains and discontinuous dynamic recrystallization (DDRX) grains featured with the local bulge of grain boundaries along TD. This was due to the smaller average Schmid factor and the vertical EL trend of the initial grains when the samples were stretched along TD. A model of grain evolution during the dynamic recrystallization (DRX) along RD and TD was proposed based on EBSD results. The Schmid factor and banded structure had a more prominent effect on the hot ductility of the 2195 Al–Li alloy compared with the degree of DRX, thus presenting a higher EL and better hot ductility along RD. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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14 pages, 7698 KiB

Open AccessArticle

Effect of Traverse Speed Variation on Microstructural Properties and Corrosion Behavior of Friction Stir Welded WE43 Mg Alloy Joints

by Yusra Saman Khan, Mustufa Haider Abidi, Waqar Malik, Nadeem Fayaz Lone, Mohamed K. Aboudaif and Muneer Khan Mohammed

Materials 2023, 16(14), 4902; https://doi.org/10.3390/ma16144902 - 9 Jul 2023

Cited by 6 | Viewed by 2158

Abstract

The growing demand for Magnesium in the automotive and aviation industries has enticed the need to improve its corrosive properties. In this study, the WE43 magnesium alloys were friction stir welded (FSW) by varying the traverse speed. FSW eliminates defects such as liquefication [...] Read more.

The growing demand for Magnesium in the automotive and aviation industries has enticed the need to improve its corrosive properties. In this study, the WE43 magnesium alloys were friction stir welded (FSW) by varying the traverse speed. FSW eliminates defects such as liquefication cracking, expulsion, and voids in joints encountered frequently in fusion welding of magnesium alloys. The microstructural properties were scrutinized using light microscopy (LM) and scanning electron microscopy (SEM). Additionally, the elemental makeup of precipitates was studied using electron dispersive X-ray spectroscopy (EDS). The electrochemical behavior of specimens was evaluated by employing potentiodynamic polarization tests and was correlated with the microstructural properties. A defect-free weldment was obtained at a traverse and rotational speed of 100 mm/min and 710 rpm, respectively. All weldments significantly improved corrosion resistance compared to the base alloy. Moreover, a highly refined microstructure with redistribution/dissolution of precipitates was obtained. The grain size was reduced from 256 µm to around 13 µm. The corrosion resistance of the welded sample was enhanced by 22 times as compared to the base alloy. Hence, the reduction in grain size and the dissolution/distribution of secondary-phase particles within the Mg matrix are the primary factors for the enhancement of anti-corrosion properties. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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11 pages, 5088 KiB

Open AccessArticle

Effect of Sm + Er and Heat Treatment on As-Cast Microstructure and Mechanical Properties of 7055 Aluminum Alloy

by Jue Wang and Faguo Li

Materials 2023, 16(13), 4846; https://doi.org/10.3390/ma16134846 - 5 Jul 2023

Cited by 4 | Viewed by 1936

Abstract

The 7055 aluminum alloy is an ultra-high strength aluminum alloy, which is widely used in the aerospace field and new energy automobile manufacturing industry. As it retains high strength, its plastic deformation ability needs to be improved, which limits its application in plastic [...] Read more.

The 7055 aluminum alloy is an ultra-high strength aluminum alloy, which is widely used in the aerospace field and new energy automobile manufacturing industry. As it retains high strength, its plastic deformation ability needs to be improved, which limits its application in plastic processing. In this study, the cast grains of the 7055 aluminum alloy were refined by adding Sm + Er, and the proper heat treatment procedure was utilized to further precipitate the rare earth phase in order to increase the alloy’s strength and toughness. The grain size, microstructure and phase were characterized by optical microscopes (OMs), scanning electron microscopy—energy spectrum (SEM-EDS) and a XRD diffractometer (XRD). The macroscopic hardness, yield strength and tensile strength of alloy materials were measured by a hardness meter and universal electronic tensile machine. The results showed that the as-cast sample and the heat treatment sample all contained Al₁₀Cu₇Sm₂ and Al₈Cu₄Er rare earth phases. But, after heat treatment, the volume percentage of the rare earth phase dramatically increased and the dispersion was more unified. When 0.3 wt.%Sm and 0.1 wt.%Er were added, the grain size could be refined to 53 μm. With the increase in the total content of rare earth elements, the refining effect first increased and then decreased. Under 410 °C solid solution for 2 h + 150 °C and aging for 12 h, the macroscopic hardness, yield strength, tensile strength and elongation of 0.3 wt.%Sm + 0.1 wt.%Er + 7055 as-cast samples were 155.8 HV, 620.5 MPa, 658.1 MPa and 11.90%, respectively. After the addition of Sm and Er elements and heat treatment, the grain refinement effect of 7055 aluminum alloy was obvious and the plastic property was greatly improved under the premise of maintaining its high-strength advantage. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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22 pages, 6768 KiB

Open AccessArticle

Comprehensive Research of FSW Joints of AZ91 Magnesium Alloy

by Krzysztof Mroczka, Stanisław Dymek, Aleksandra Węglowska, Carter Hamilton, Mateusz Kopyściański, Adam Pietras and Paweł Kurtyka

Materials 2023, 16(11), 3953; https://doi.org/10.3390/ma16113953 - 25 May 2023

Cited by 6 | Viewed by 1839

Abstract

For the friction stir welding (FSW) of AZ91 magnesium alloy, low tool rotational speeds and increased tool linear speeds (ratio 3.2) along with a larger diameter shoulder and pin are utilized. The research focused on the influence of welding forces and the characterization [...] Read more.

For the friction stir welding (FSW) of AZ91 magnesium alloy, low tool rotational speeds and increased tool linear speeds (ratio 3.2) along with a larger diameter shoulder and pin are utilized. The research focused on the influence of welding forces and the characterization of the welds by light microscopy, scanning electron microscopy with an electron backscatter diffraction system (SEM-EBSD), hardness distribution across the joint cross-section, joint tensile strength, and SEM examination of fractured specimens after tensile tests. The micromechanical static tensile tests performed are unique and reveal the material strength distribution within the joint. A numerical model of the temperature distribution and material flow during joining is also presented. The work demonstrates that a good-quality joint can be obtained. A fine microstructure is formed at the weld face, containing larger precipitates of the intermetallic phase, while the weld nugget comprises larger grains. The numerical simulation correlates well with experimental measurements. On the advancing side, the hardness (approx. 60 HV0.1) and strength (approx. 150 MPa) of the weld are lower, which is also related to the lower plasticity of this region of the joint. The strength (approx. 300 MPa) in some micro-areas is significantly higher than that of the overall joint (204 MPa). This is primarily attributable to the macroscopic sample also containing material in the as-cast state, i.e., unwrought. The microprobe therefore includes less potential crack nucleation mechanisms, such as microsegregations and microshrinkage. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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12 pages, 3855 KiB

Open AccessArticle

Degree of Impurity and Carbon Contents in the Grain Size of Mg-Al Magnesium Alloys

by Sung-Su Jung, Yong-Ho Park and Young-Cheol Lee

Materials 2023, 16(8), 3069; https://doi.org/10.3390/ma16083069 - 13 Apr 2023

Cited by 4 | Viewed by 1977

Abstract

In this study, the tendency of having different grain structures depending on the impurity levels in AZ91 alloys was investigated. Two types of AZ91 alloys were analyzed: commercial-purity AZ91 and high-purity AZ91. The average grain size of the commercial-purity AZ91 alloy and high-purity [...] Read more.

In this study, the tendency of having different grain structures depending on the impurity levels in AZ91 alloys was investigated. Two types of AZ91 alloys were analyzed: commercial-purity AZ91 and high-purity AZ91. The average grain size of the commercial-purity AZ91 alloy and high-purity AZ91 is 320 µm and 90 µm, respectively. Thermal analysis revealed negligible undercooling in the high-purity AZ91 alloy, while undercooling of 1.3 °C was observed in the commercial-purity AZ91 alloy. A CS analyzer was employed to precisely analyze the carbon composition of both alloys. The carbon content of the high-purity AZ91 alloy was found to be 197 ppm, while the commercial-purity AZ91 alloy contained 104 ppm, indicating a difference of approximately 2 times. The higher carbon content in the high-purity AZ91 alloy is believed to be due to the use of high-purity pure Mg in its production (the carbon content of high-purity pure Mg is 251 ppm). To simulate the vacuum distillation process commonly used in the production of high-purity Mg ingots, experiments were conducted to investigate the reaction of carbon with oxygen to produce CO and CO₂. XPS analysis and simulation results for activities confirmed the formation of CO and CO₂ during the vacuum distillation process. It could be speculated that the carbon sources in the high-purity Mg ingot provide Al-C particles, which act as nucleants for Mg grains in the high-purity AZ91 alloy. Thus, it can be considered the main reason that high-purity AZ91 alloys have a finer grain structure than that of commercial-purity AZ91 alloys. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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15 pages, 28258 KiB

Open AccessArticle

Investigation of the Mechanical Properties and Microstructure of the Co40NiCrMo Alloy Used for STACERs and Prepared by the CSPB Process and the Winding and Stabilization Method

by Ruilong Lu, Jingtao Han, Jiawei Liu, Zhanhua Li, Congfa Zhang, Cheng Liu and Xiaoyan Ma

Materials 2023, 16(8), 2970; https://doi.org/10.3390/ma16082970 - 8 Apr 2023

Cited by 2 | Viewed by 1586

Abstract

The Co40NiCrMo alloy, used for STACERs fabricated by the CSPB (compositing stretch and press bending) process (cold forming) and the winding and stabilization (winding and heat treatment) method, was investigated with regard to its tensile property, residual stress, and microstructure. The Co40NiCrMo STACER [...] Read more.

The Co40NiCrMo alloy, used for STACERs fabricated by the CSPB (compositing stretch and press bending) process (cold forming) and the winding and stabilization (winding and heat treatment) method, was investigated with regard to its tensile property, residual stress, and microstructure. The Co40NiCrMo STACER prepared by the winding and stabilization method was strengthened with lower ductility (tensile strength/elongation: 1562 MPa/5%) compared to that prepared by CSPB (tensile strength/elongation: 1469 MPa/20.4%). The residual stress of the STACER prepared by winding and stabilization (τ_xy = −137 MPa) showed consistency with that obtained through CSPB (τ_xy = −131 MPa). Combined with the driving force and pointing accuracy performances, the optimum heat treatment parameters for the winding and stabilization method were determined as 520 °C + 4 h. The HABs in the winding and stabilization STACER (98.3%, of which 69.1% were Σ3 boundaries) were much higher than those in the CSPB STACER (34.6%, of which 19.2% were Σ3 boundaries), while deformation twins and h.c.p ε-platelet networks were present in the CSPB STACER, and many more annealing twins appeared in the winding and stabilization STACER. It was concluded that the strengthening mechanism in the CSPB STACER is the combined action of deformation twins and h.c.p ε-platelet networks, while for the winding and stabilization STACER, annealing twins play the dominant role. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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14 pages, 8423 KiB

Open AccessArticle

Investigation of the Hot Stamping-in-Die Quenching Composite Forming Process of 5083 Aluminum Alloy Skin

by Lingling Yi, Ge Yu, Ziming Tang, Xin Li and Zhengwei Gu

Materials 2023, 16(7), 2742; https://doi.org/10.3390/ma16072742 - 29 Mar 2023

Cited by 5 | Viewed by 2152

Abstract

Aluminum alloy has been used as the skin material for rail vehicles and automobiles to meet the requirements of environmental protection. The hot stamping-in-die quenching composite forming (HFQ) process is a promising technology to compensate for the poor formability of the aluminum alloy [...] Read more.

Aluminum alloy has been used as the skin material for rail vehicles and automobiles to meet the requirements of environmental protection. The hot stamping-in-die quenching composite forming (HFQ) process is a promising technology to compensate for the poor formability of the aluminum alloy sheet at room temperature. In this paper, the high-temperature mechanical properties of 5083 aluminum alloy under various temperature (200 °C, 300 °C, 400 °C, 450 °C) and strain rate conditions (0.01 s⁻¹, 0.10 s⁻¹, 1.00 s⁻¹) were investigated by uniaxial tensile tests. The finite element software of PAM-STAMP was employed to simulate the forming process of high-speed train skin. The effects of forming method and process parameters on the minimum thickness and springback of the skin were analyzed using the Response Surface Methodology (RSM). After parameter optimization, the forming experiment verified the simulation results and the test part met the quality requirements: the thickness above 3.84 mm and the springback within 1.1 mm. Mechanical properties of the sheet before and after HFQ were examined by uniaxial tensile tests at room temperature. It can be inferred from the comparison that the yield strength of the Al5083 sheet increases, but the elongation decreases from the HFQ process. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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11 pages, 2920 KiB

Open AccessArticle

Rheological Behavior of the A356 Alloy in the Semisolid State at Low Shear Rates

by Oscar Martin-Raya, Sergi Menargues, Enric Martin, Maria Teresa Baile and Josep A. Picas

Materials 2023, 16(6), 2280; https://doi.org/10.3390/ma16062280 - 12 Mar 2023

Cited by 5 | Viewed by 2008

Abstract

To control the semisolid processing of aluminum alloys produced by the additive manufacturing technique, an exhaustive knowledge of their rheological behavior is required. In the semisolid state, metallic materials can show rheological characteristics similar to those of polymers, so semisolid state shaping is [...] Read more.

To control the semisolid processing of aluminum alloys produced by the additive manufacturing technique, an exhaustive knowledge of their rheological behavior is required. In the semisolid state, metallic materials can show rheological characteristics similar to those of polymers, so semisolid state shaping is one of the currently considered routes for additive manufacturing with metallic materials. In this work, an approximation of the rheological control of the A356 aluminum alloy for its subsequent 3D manufacturing was carried out at a very low shear rate. A continuous cooling rheometer was designed and used, evaluating the influence of different process parameters on the viscosity variation of the aluminum alloy in the semisolid state. The results show an anomalous flow variation, indicating dilatant, and not thixotropic behavior, for very low shear rates. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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13 pages, 5856 KiB

Open AccessArticle

Short Circuiting Transfer, Formation, and Microstructure of Ti-6Al-4V Alloy by External Longitudinal Magnetic Field Hybrid Metal Inert Gas Welding Additive Manufacturing

by Chao Shi, Hongwei Sun and Jiping Lu

Materials 2022, 15(21), 7500; https://doi.org/10.3390/ma15217500 - 26 Oct 2022

Cited by 7 | Viewed by 1718

Abstract

In this work, the external longitudinal magnetic field hybrid metal inert gas welding (M-MIG) additive manufacturing method is employed to produce the Ti-6Al-4V alloy part. The effect of process parameters on the droplet transfer formation and microstructure of the part was studied by [...] Read more.

In this work, the external longitudinal magnetic field hybrid metal inert gas welding (M-MIG) additive manufacturing method is employed to produce the Ti-6Al-4V alloy part. The effect of process parameters on the droplet transfer formation and microstructure of the part was studied by a high-speed camera, optical microscope, and electron backscattered diffraction. The results showed that a typical short-circuiting transfer was obtained with the wire feeding speed of 2 m/min–4 m/min. An external longitudinal magnetic field had an obvious effect on the arc shape. The uniform formation of the deposition layer was obtained with the wire feeding speed of 4 m/min. The width of M-MIG deposition layer was greater than that of the MIG, and the width of M-MIG deposition layer was increased with the increase of the magnetic excitation current. The microstructure of the deposition layer was mainly comprised of acicular martensite α’ and massive martensite α_m. In addition, the β grain size in the M-MIG was less than that of the MIG. The average microhardness of the MIG deposition layer was 281.6 HV, which was less than that of M-MIG. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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11 pages, 9074 KiB

Open AccessArticle

Influence of Annealing Time on Microstructure and Mechanical Properties of Al-14.5Si Alloy Prepared by Super-Gravity Solidification and Cold-Rolling

by Zhanghua Gan, Qian Ni, Yuanyuan Huang, Yin Su, Yuehui Lu, Chuandong Wu and Jing Liu

Materials 2022, 15(16), 5475; https://doi.org/10.3390/ma15165475 - 9 Aug 2022

Cited by 2 | Viewed by 1674

Abstract

In this paper, super-gravity solidification and cold-rolling were utilized to obtain Al-14.5Si alloys. The influence of annealing time on microstructure and mechanical properties of Al-14.5Si alloys was investigated. Our results indicated that high elongation was achieved by super-gravity solidification due to the submicron [...] Read more.

In this paper, super-gravity solidification and cold-rolling were utilized to obtain Al-14.5Si alloys. The influence of annealing time on microstructure and mechanical properties of Al-14.5Si alloys was investigated. Our results indicated that high elongation was achieved by super-gravity solidification due to the submicron eutectic Si, making it possible to undertake the conventional cold-rolling. The yield strength (~214 ± 11 MPa) was significantly enhanced (~68.5%) after cold-rolling mainly due to high dislocation density. The coarsening of eutectic Si could be observed during annealing, which resulted in a decrease in yield strength. The elimination of internal stress and lattice distortion during annealing led to a decrease in micro-cracks/voids beneath the fracture surface during tensile testing, which in turn enhanced the elongation. Full article

(This article belongs to the Special Issue Advanced Light Metal and Alloys: Preparation, Characterization, and Applications)

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