Editorial

3 pages, 166 KiB

Open AccessEditorial

Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys

by Claudio Testani

Metals 2021, 11(10), 1555; https://doi.org/10.3390/met11101555 - 29 Sep 2021

Cited by 1 | Viewed by 927

The demand for lightweight metals and related alloys is still the most suitable solution to many high-tech applications, including sports equipment and automotive components where alternate movements require low inertia [...] Full article

(This article belongs to the Special Issue Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys)

Research

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13 pages, 4916 KiB

Open AccessArticle

Experimental Investigation of Material Properties in FSW Dissimilar Aluminum-Steel Lap Joints

by Michelangelo Mortello, Matteo Pedemonte, Nicola Contuzzi and Giuseppe Casalino

Metals 2021, 11(9), 1474; https://doi.org/10.3390/met11091474 - 16 Sep 2021

Cited by 9 | Viewed by 1748

Abstract

The friction stir lap welding of AA5083 H111 aluminum alloy and S355J2 grade DH36 structural steel was investigated. A polycrystalline cubic boron nitride with tungsten and rhenium additives tool was used. According to visual inspection, radiographic examination, and tensile test, it was observed [...] Read more.

The friction stir lap welding of AA5083 H111 aluminum alloy and S355J2 grade DH36 structural steel was investigated. A polycrystalline cubic boron nitride with tungsten and rhenium additives tool was used. According to visual inspection, radiographic examination, and tensile test, it was observed that the best results were obtained for rotation speeds of about 700–800 rpm, with a feed speed ranging between 1.3 and 1.9 mm/s. From the fatigue tests, it is possible to state that there was a preferential propagation of cracks in the part of the aluminum alloy base material. Furthermore, a different response to fatigue stress for samples extracted from the same weld at different positions was observed, which introduces an overall variability in weld behavior along the welding direction. The specimens obtained in the second part of the weld endured a larger number of cycles before reaching failure, which can be related to progressively varying thermal conditions, dissipation behavior, and better metal coupling as the tool travels along the welding line. Full article

(This article belongs to the Special Issue Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys)

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21 pages, 7931 KiB

Open AccessFeature PaperArticle

Microstructure Evaluation, Quantitative Phase Analysis, Strengthening Mechanism and Influence of Hybrid Reinforcements (β-SiCp, Bi and Sb) on the Collective Mechanical Properties of the AZ91 Magnesium Matrix

by Song-Jeng Huang, Sikkanthar Diwan Midyeen, Murugan Subramani and Chao-Ching Chiang

Metals 2021, 11(6), 898; https://doi.org/10.3390/met11060898 - 31 May 2021

Cited by 8 | Viewed by 2609

Abstract

Gravitational melt-stir casting produced hybrid nano-reinforcements (β-SiCp) and micro-reinforcements (Bi and Sb) of AZ91 composites. SiCp-diffused discontinuous β-Mg₁₇Al₁₂ precipitation with a vital factor of SiC was exhibited at the grain boundary region, formulated Mg₃Si throughout the composite and [...] Read more.

Gravitational melt-stir casting produced hybrid nano-reinforcements (β-SiCp) and micro-reinforcements (Bi and Sb) of AZ91 composites. SiCp-diffused discontinuous β-Mg₁₇Al₁₂ precipitation with a vital factor of SiC was exhibited at the grain boundary region, formulated Mg₃Si throughout the composite and changed the present Mg_0.97Zn_0.03 phases. The creation of Mg₂Si (cubic) and SiC (rhombohedral axes) enhanced the microhardness by 18.60% in a 0.5 wt.% SiCp/AZ91 matrix. The microhardness of 1 wt.% SiCp/AZ91 was slightly reduced after Mg_0.97Zn_0.03 (hexagonal) reduction. The best ultimate tensile value obtained was about 169.33 MPa (increased by 40.10%) in a 0.5 wt.% SiCp/AZ91 matrix. Microelements Bi and Sb developed Mg₃Bi₂, Mg₃Sb₂ and monoclinic C₆₀ phases. The best peak yield strength of 82.75 MPa (increased by 19.85%) was obtained with the addition of 0.5 wt.% SiCp/1 wt.% Bi/0.4 wt.% Sb. The mismatch of the coefficient of thermal expansion of segregated particles and the AZ91 matrix, the shear transfer effect and the Orowan effect, combined with the quantitative value of phase existence, improved the compressive strengths of the composites with 0.5 wt.% β-SiCp, 1 wt.% β-SiCp and 0.5 wt.% SiCp/1 wt.% Bi/0.4 wt.% Sb by 2.68%, 6.23% and 8.38%, respectively. Notably, the Charpy impact strengths of 0.5 wt.% and 1 wt.% β-SiCp-added AZ91 composites were enhanced by 236% (2.89 J) and 192% (2.35 J), respectively. The addition of Bi and Sb with SiCp resulted in the formation of a massive phase of brittle Al₆Mn. Al–Mn-based phases (developed huge voids and cavities) remarkably reduced impact values by 80% (0.98 J). The discussion covers the quantitative analyses of X-ray diffraction, optical microscopy and scanning electron microscopy results and fracture surfaces. Full article

(This article belongs to the Special Issue Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys)

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13 pages, 20678 KiB

Open AccessArticle

Influence of Additive Manufactured Stainless Steel Tool Electrode on Machinability of Beta Titanium Alloy

by Ragavanantham Shanmugam, Monsuru Ramoni, Geethapriyan Thangamani and Muthuramalingam Thangaraj

Metals 2021, 11(5), 778; https://doi.org/10.3390/met11050778 - 10 May 2021

Cited by 48 | Viewed by 3226

Abstract

Additive manufacturing technology provides a gateway to completely new horizons for producing a wide range of components, such as manufacturing, medicine, aerospace, automotive, and space explorations, especially in non-conventional manufacturing processes. The present study analyzes the influence of the additive manufactured tool in [...] Read more.

Additive manufacturing technology provides a gateway to completely new horizons for producing a wide range of components, such as manufacturing, medicine, aerospace, automotive, and space explorations, especially in non-conventional manufacturing processes. The present study analyzes the influence of the additive manufactured tool in electrochemical micromachining (ECMM) on machining beta titanium alloy. The influence of different machining parameters, such as applied voltage, electrolytic concentration, and duty ratio on material removal rate (MRR), overcut, and circularity was also analyzed. It was inferred that the additive manufactured tool can produce better circularity and overcut than a bare tool due to its higher corrosion resistance and localization effect. The additive manufactured tool can remove more material owing to its strong atomic bond of metals and higher electrical conductivity. Full article

(This article belongs to the Special Issue Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys)

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13 pages, 4504 KiB

Open AccessArticle

Casting Microstructure Inspection Using Computer Vision: Dendrite Spacing in Aluminum Alloys

by Filip Nikolić, Ivan Štajduhar and Marko Čanađija

Metals 2021, 11(5), 756; https://doi.org/10.3390/met11050756 - 04 May 2021

Cited by 13 | Viewed by 4030

Abstract

This paper investigates the determination of secondary dendrite arm spacing (SDAS) using convolutional neural networks (CNNs). The aim was to build a Deep Learning (DL) model for SDAS prediction that has industrially acceptable prediction accuracy. The model was trained on images of polished [...] Read more.

This paper investigates the determination of secondary dendrite arm spacing (SDAS) using convolutional neural networks (CNNs). The aim was to build a Deep Learning (DL) model for SDAS prediction that has industrially acceptable prediction accuracy. The model was trained on images of polished samples of high-pressure die-cast alloy EN AC 46000 AlSi9Cu3(Fe), the gravity die cast alloy EN AC 51400 AlMg5(Si) and the alloy cast as ingots EN AC 42000 AlSi7Mg. Color images were converted to grayscale to reduce the number of training parameters. It is shown that a relatively simple CNN structure can predict various SDAS values with very high accuracy, with a

R^{2}

value of 91.5%. Additionally, the performance of the model is tested with materials not used during training; gravity die-cast EN AC 42200 AlSi7Mg0.6 alloy and EN AC 43400 AlSi10Mg(Fe) and EN AC 47100 Si12Cu1(Fe) high-pressure die-cast alloys. In this task, CNN performed slightly worse, but still within industrially acceptable standards. Consequently, CNN models can be used to determine SDAS values with industrially acceptable predictive accuracy. Full article

(This article belongs to the Special Issue Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys)

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8 pages, 4828 KiB

Open AccessArticle

Ti Interlayer Mediated Uniform NiGe Formation under Low-Temperature Microwave Annealing

by Jun Yang, Yunxia Ping, Wei Liu, Wenjie Yu, Zhongying Xue, Xing Wei, Aimin Wu and Bo Zhang

Metals 2021, 11(3), 488; https://doi.org/10.3390/met11030488 - 15 Mar 2021

Cited by 1 | Viewed by 1579

Abstract

The reactions between nickel and germanium are investigated by the incorporation of a titanium interlayer on germanium (100) substrate. Under microwave annealing (MWA), the nickel germanide layers are formed from 150 °C to 350 °C for 360 s in ambient nitrogen atmosphere. It [...] Read more.

The reactions between nickel and germanium are investigated by the incorporation of a titanium interlayer on germanium (100) substrate. Under microwave annealing (MWA), the nickel germanide layers are formed from 150 °C to 350 °C for 360 s in ambient nitrogen atmosphere. It is found that the best quality nickel germanide is achieved by microwave annealing at 350 °C. The titanium interlayer becomes a titanium cap layer after annealing. Increasing the diffusion of Ni by MWA and decreasing the diffusion of Ni by Ti are ascribed to induce the uniform formation of nickel germanide layer at low MWA temperature. Full article

(This article belongs to the Special Issue Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys)

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8 pages, 3818 KiB

Open AccessCommunication

Analysis of Nanoprecipitation Effect on Toughness Behavior in Warm Worked AA7050 Alloy

by Claudio Testani, Giuseppe Barbieri and Andrea Di Schino

Metals 2020, 10(12), 1693; https://doi.org/10.3390/met10121693 - 20 Dec 2020

Cited by 2 | Viewed by 1490

Abstract

Commonly adopted main methods aimed to improve the strength–toughness combination of high strength aluminum alloys are based on a standard process. Such a process includes alloy solution heat treatment, water-quench and reheating at controlled temperature for ageing holding times. Some alloys request an [...] Read more.

Commonly adopted main methods aimed to improve the strength–toughness combination of high strength aluminum alloys are based on a standard process. Such a process includes alloy solution heat treatment, water-quench and reheating at controlled temperature for ageing holding times. Some alloys request an intermediate cold working hardening step before ageing for an optimum strength result. Recently a warm working step has been proposed and applied. This replaces the cold working after solution treatment and quenching and before the final ageing treatment. Such an alternative process proved to be very effective in improving strength–toughness behavior of 7XXX aluminum alloys. In this paper the precipitation state following this promising process is analyzed and compared to that of the standard route. The results put in evidence the differences in nanoprecipitation densities that are claimed to be responsible for strength and toughness improved properties. Full article

(This article belongs to the Special Issue Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys)

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13 pages, 6532 KiB

Open AccessArticle

Production of Oxide Dispersion Strengthened Mg-Zn-Y Alloy by Equal Channel Angular Pressing of Mechanically Alloyed Powder

by Keng-Liang Ou, Chia-Chun Chen and Chun Chiu

Metals 2020, 10(5), 679; https://doi.org/10.3390/met10050679 - 21 May 2020

Cited by 4 | Viewed by 2089

Abstract

Mg-Zn-Y alloys with long-period stacking ordered structures (LPSO) have attracted attention due to their excellent mechanical properties. In addition to the LPSO structure, Mg alloys can also be strengthened by oxide particles. In the present study, oxide dispersion strengthened Mg₉₇Zn₁ [...] Read more.

Mg-Zn-Y alloys with long-period stacking ordered structures (LPSO) have attracted attention due to their excellent mechanical properties. In addition to the LPSO structure, Mg alloys can also be strengthened by oxide particles. In the present study, oxide dispersion strengthened Mg₉₇Zn₁Y₂ (at%) alloys were prepared by equal channel angular pressing (ECAP) of mechanical alloyed (MA) powder under an oxygen gas atmosphere. The 20-h-MA powder had a particle size of 28 μm and a crystallite size of 36 nm. During the MA process followed by ECAP, an Mg matrix with dispersed Y₂O₃ (and MgO) particles was formed. The alloy processed by ECAP exhibited a hardness of 110 HV and a compressive strength of 185 MPa. Compared to pure Mg, the increased hardness was due to the dispersion strengthening of Y₂O₃ and MgO particles and solution strengthening of Zn and Y. Full article

(This article belongs to the Special Issue Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys)

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21 pages, 16187 KiB

Open AccessArticle

Production and Properties of Electron-Beam-Welded Joints on Ti-TiB Titanium Alloys

by Petro Loboda, Constantine Zvorykin, Volodymyr Zvorykin, Eduard Vrzhyzhevskyi, Tatjana Taranova and Valery Kostin

Metals 2020, 10(4), 522; https://doi.org/10.3390/met10040522 - 18 Apr 2020

Cited by 7 | Viewed by 2336

Abstract

In this article, structural features of Ti-TiB and (α+β) Ti alloys in the initial state, in the weld and in the heat-affected zone of electron beam welds were investigated. The influences of welding parameters, such as influence of the electron beam velocity, preheating [...] Read more.

In this article, structural features of Ti-TiB and (α+β) Ti alloys in the initial state, in the weld and in the heat-affected zone of electron beam welds were investigated. The influences of welding parameters, such as influence of the electron beam velocity, preheating of the welded alloys and the subsequent annealing of the welded joint on the its microstructure, and the mechanical strength and ductility of the critical elements of the joint were studied by scanning electron microscopy using microprobe Auger spectral and X-ray diffraction analysis and tensile tests. It has been shown that the conditions for rapid crystallization of the material from the melt of the weld contribute to refining of reinforcing fibers of TiB and its hardening in comparison with the starting material Ti-TiB. Besides that, influences of the preferential orientation of TiB reinforcing microfibers (along and across the welded butt joint) on the mechanical properties of the welded joint were investigated bz tensile testing. Using the methods of fractographic analysis, the effect of the boron-containing phase on the fracture character of Ti-TiB welded joints was established. It was shown that, along with the strengthening effect, TiB fibers cause embrittlement of the material. Full article

(This article belongs to the Special Issue Advances in Processing and Mechanical Behavior in Lightweight Metals and Alloys)

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