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16 pages, 10480 KiB

Open AccessArticle

Effects of Friction Stir Processing on the Microstructure and Mechanical Properties of an Ultralight Mg-Li Alloy

by Wenjie Song, Zongyu Wu, Shuai He, Jie Liu, Guang Yang, Yanhui Liu, Huijin Jin, Yupeng He and Zhonghao Heng

Crystals 2024, 14(1), 64; https://doi.org/10.3390/cryst14010064 - 04 Jan 2024

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Abstract

Magnesium–lithium alloys are arguably the lightest metal structural materials but have low strength. In order to increase strength, friction stir processing (FSP) is applied to a hot-rolled Mg-10Li-3Al-3Zn (LA103Z) sheet to study the effects on the microstructure and mechanical properties. In this study, [...] Read more.

Magnesium–lithium alloys are arguably the lightest metal structural materials but have low strength. In order to increase strength, friction stir processing (FSP) is applied to a hot-rolled Mg-10Li-3Al-3Zn (LA103Z) sheet to study the effects on the microstructure and mechanical properties. In this study, the strengthening mechanisms of various FSP regions of an Mg-Li alloy were clarified by a combination of numerical simulation and experimental method. Based on ANSYS APDL, a finite element model with a moving heat source is established. Rotational speeds of 800, 1000, and 1200 rpm and traverse speeds of 100, 110, and 120 mm/min were used in this research. The simulation results confirm that the influence of the rotation speed on the alloy temperature field is greater than that of the travel speed. The temperature of the processing area increases with an increase in rotation speed and decreases with an increase in travel speed. Then, hot-rolled LA103Z alloy plates are processed by FSP. The correspondence between the numerical simulation and experiment was verified by infrared thermography. The results indicate that FSP decreases the grain size significantly for the dynamic recrystallization and dramatic mechanical crushing of the stirring pin. The α-Mg and AlLi are solid soluted in the β-Li matrix. The tensile strength of the processing zone is 260.67 MPa (1000 rpm, 110 mm/min) versus the 170.47 MPa of the base metal. The SZ has the highest microhardness of 77.8 HV (800 rpm, 120 mm/min) and decreases gradually to the BM. The severe deformation, recrystallization, and solid solution of the α-Mg are important factors contributing to the improved mechanical properties. Full article

(This article belongs to the Special Issue Progress in Light Alloys)

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12 pages, 11301 KiB

Open AccessArticle

The Role of Boron Addition on Solidification Behavior and Microstructural Evolution of a High Niobium-Containing TiAl Alloy

by Fan Zhang, Zeen Wu, Xiaoye Wang, Tiebang Zhang, Yongchun Zhang and Qiao Li

Crystals 2023, 13(10), 1494; https://doi.org/10.3390/cryst13101494 - 14 Oct 2023

Cited by 1 | Viewed by 760

Abstract

This work investigates the role of boron addition in the solidification behavior and microstructural evolution during the heat treatment process of Ti-46Al-8Nb-xB (x = 0.1, 0.7, 1.4, 2.5 at.%). The results show that the solid solution boron element prefers to [...] Read more.

This work investigates the role of boron addition in the solidification behavior and microstructural evolution during the heat treatment process of Ti-46Al-8Nb-xB (x = 0.1, 0.7, 1.4, 2.5 at.%). The results show that the solid solution boron element prefers to occupy the interstitial vacancies of the α₂ phase in the alloy. However, the solid solubility of the boron element in high Nb-containing TiAl alloys is extremely low. Therefore, it does not have a significant effect on the lattice distortion of α₂ and γ phases in the alloy. When the boron content is added up to 0.1%, a B27-type TiB precipitated phase is produced in the alloy. The morphology of borides mostly shows short rod-like structures, and a few show long curved shapes. And the addition of boron refines both the alloy colony size and the lamellar structure. Furthermore, it is also found that boron addition weakens the casting texture of the alloy. After a solid solution and different time aging heat treatment process, the microstructure of different boron content alloys have experienced obvious coarsening phenomenon. However, the morphology of the boride is closely related to boron content and heat treatment. Full article

(This article belongs to the Special Issue Progress in Light Alloys)

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13 pages, 11518 KiB

Open AccessArticle

In Situ Formation of Al₃Ti and Its Effects on the Microstructure, Hardness and Tribological Properties of Al Matrix Composites with Various Ti Contents

by Fei Lin, Mengyuan Ren, Hui Wu, Fanghui Jia, Ming Yang, Zhixin Chen and Zhengyi Jiang

Crystals 2023, 13(5), 805; https://doi.org/10.3390/cryst13050805 - 11 May 2023

Cited by 3 | Viewed by 1201

Abstract

At present, Al matrix composites (AMCs) have drawn much attention owing to their light weight, high specific strength, high thermal conductivity, and superior excellent wear resistance, which endows them with great potential in the aerospace, automobile and military industries. In this study, AMCs [...] Read more.

At present, Al matrix composites (AMCs) have drawn much attention owing to their light weight, high specific strength, high thermal conductivity, and superior excellent wear resistance, which endows them with great potential in the aerospace, automobile and military industries. In this study, AMCs with different Ti contents (0, 5 and 10 vol.%) were prepared by powder metallurgy. During the sintering, Al₃Ti particles were in situ formed in the Al matrix. It was found that the Ti completely reacted with the Al matrix and formed fine in situ Al₃Ti particles in Al-10Ti, while some large Ti-Al₃Ti core-shell formed in Al-5Ti due to the incomplete reaction between the Ti and the Al matrix. Furthermore, the hardness of the composites was significantly improved by the in situ formed Al₃Ti particles, reaching 143.3 HV in Al-5Ti and the highest value at 331.2 HV in Al-10Ti, respectively. The wear resistance of the composites is remarkably enhanced by Al₃Ti particles compared to the unreinforced Al. Al-5Ti has the highest wear resistance among the samples. The wear resistance of the Al-10Ti composite becomes slightly deteriorated compared to Al-5Ti due to the brittle nature of Al₃Ti, which leads to a three-body abrasive wear. Full article

(This article belongs to the Special Issue Progress in Light Alloys)

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8 pages, 1916 KiB

Open AccessArticle

Effect of Lubricating Oil and Wiper on Super-High Strength 7055 Aluminum Alloy Ingots

by Xiangjie Wang, Yajun Xu, Lingfei Yang, Chengcheng Chen, Zhaoxi Song and Jianzhong Cui

Crystals 2023, 13(1), 88; https://doi.org/10.3390/cryst13010088 - 03 Jan 2023

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Abstract

The casting table with lubricating oil and wiper is applied simultaneously to produce super-high-strength 7055 aluminum alloy (Al7055) ingots, and 30 T Al7055 ingots with a diameter of 582 mm were cast successfully. In this study, the microstructure and macrosegregation of the ingots [...] Read more.

The casting table with lubricating oil and wiper is applied simultaneously to produce super-high-strength 7055 aluminum alloy (Al7055) ingots, and 30 T Al7055 ingots with a diameter of 582 mm were cast successfully. In this study, the microstructure and macrosegregation of the ingots were investigated using an optical microscope (OM). The research results show that the hydrogen content in the liquid metal can be decreased from 0.198 mL/100 g Al to 0.103 mL/100 g Al when three rotors are used in the degassing tank. Compared with the conventional hot-top casting table, the surface quality can be improved by using the casting table with oil lubrication. The temperature gradient between the ingot center and edge can be decreased by using the wiper during the casting process from 320 °C to 150 °C, the cracking tendency caused by the ingot temperature gradient can be decreased, the segregation layer thickness is decreased by about 87%, and the ingot can be homogenized at a high temperature by using the heat of the feed itself. Full article

(This article belongs to the Special Issue Progress in Light Alloys)

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18 pages, 24231 KiB

Open AccessArticle

Microstructure and Properties of Microwave-Sintered Nd₂Fe₁₄B_p/2024 Aluminum-Alloy–Co Composites

by Tao Qin, Guirong Li, Hongming Wang, Wenxue Su, Chao Dong and Jincheng Yu

Crystals 2022, 12(10), 1493; https://doi.org/10.3390/cryst12101493 - 20 Oct 2022

Cited by 1 | Viewed by 1021

Abstract

This study aimed at the preparation of a 2024 aluminum alloy (2024Al) matrix composite with high strength, high toughness and high magnetic properties that can be used in practical applications. Therefore, Nd₂Fe₁₄B_p/2024Al–Co composites with different Co contents [...] Read more.

This study aimed at the preparation of a 2024 aluminum alloy (2024Al) matrix composite with high strength, high toughness and high magnetic properties that can be used in practical applications. Therefore, Nd₂Fe₁₄B_p/2024Al–Co composites with different Co contents (wt.%) were prepared by ball milling, cold isostatic pressing and microwave sintering. The effects of the Co content on the microstructure, mechanical properties and magnetic properties of the prepared composites were studied. Under the conditions of the sintering temperature of 490 °C, heating rate of 20 min/°C and soaking time of 30 min, it was found that with the increase in Co content (0→2.5%→5%→7.5%→10%), the grain size first decreased and then increased, and reached the optimal value of about 3–5 μm when the Co content was 7.5%, with the microstructure being relatively uniform. At the same time, the compactness of the composite arrived at a maximum of 95.4%. The main particle phases in the composite were Nd₂Fe₁₄B, Nd₂ (Fe, Co)₁₄B and Co particles. In the nanoindentation test, the interface strength of the 7.5% Co sample was significantly higher than that of the Co-free sample. In addition, the microhardness, yield strength and compressive strength of the 7.5% Co sample were 152 HV, 210 MPa and 269 MPa, respectively, which increased by 67%, 78% and 75%, respectively, compared with the Co-free sample. With the increase in Co content, the remanence (Br), coercivity (H_cj) and maximum magnetic energy product ((BH) max) of the composites first increased and then decreased. When the Co content was 7.5%, the three performance indicators reached their optimum values, which were Br: 0.20 (T), H_cj: 4.6 (kOe) and (BH)_max: 28.36 (kJ/m³). The expected goal of the lightweight magnetic materials was achieved, and the action mechanism of Co addition in the composites was also analyzed in detail. Full article

(This article belongs to the Special Issue Progress in Light Alloys)

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12 pages, 3360 KiB

Open AccessArticle

Effects of Pre-Deformation under Tension and Annealing Process on the Microstructure and Properties of Al-6Mg-1.0Mn Extruded Wide Reinforcement Plate

by Pengwei Li, Qiqiang Han, Wei Sun, Xiangjie Wang, Jianzhong Cui, Rui Wang, Chunzhong Liu and Min Jiang

Crystals 2022, 12(10), 1415; https://doi.org/10.3390/cryst12101415 - 06 Oct 2022

Viewed by 1143

Abstract

In order to achieve the combination of mechanical and corrosion properties for the Al-Mg-Mn alloy, a novel combination of pre-deformation under tension and an annealing process was investigated on the microstructure and properties of the Al-6Mg-1.0Mn extruded wide reinforcing plate. This was conducted [...] Read more.

In order to achieve the combination of mechanical and corrosion properties for the Al-Mg-Mn alloy, a novel combination of pre-deformation under tension and an annealing process was investigated on the microstructure and properties of the Al-6Mg-1.0Mn extruded wide reinforcing plate. This was conducted by means of a tensile test, an intergranular corrosion test, scanning electron microscopy (SEM), and transmission electron microscope (TEM) experiments. The results showed that when the pre-deformation under tension in the range of 10–14%, the corrosion performance is first decreased, and then increases with the increase in temperature, becoming stable at 300 °C. After stabilization annealing at 300 °C for 2 h and then sensitizing at 150 °C for 10–200 h, the intergranular corrosion resistance of the aluminum alloy first decreases and then increases as the sensitization time is prolonged. When the sensitization time exceeds 50 h, the intergranular corrosion resistance is significantly improved. After 14% pretension and stabilization annealing at 300 °C for 2 h, the tensile strength, yield strength, and elongation of the alloy reached 360 MPa, 205 MPa, and 18.5%, and a good combination of strength and corrosion resistance of Al-Mg-Mn alloys could be obtained. These excellent properties were attributed to the continuous distribution of β-phase at the grain boundaries, and the combination of pre-deformation under tension with the annealing process promotes the dynamic precipitation of nanoparticles and the formation of substructure. Full article

(This article belongs to the Special Issue Progress in Light Alloys)

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11 pages, 3726 KiB

Open AccessArticle

Microstructure and Its Effect on the Intergranular Corrosion Properties of 2024-T3 Aluminum Alloy

by Xiang Xiao, Zeyu Zhou, Cheng Liu and Lingfei Cao

Crystals 2022, 12(3), 395; https://doi.org/10.3390/cryst12030395 - 15 Mar 2022

Cited by 7 | Viewed by 3691

Abstract

Intergranular corrosion is the main corrosion type of Al-Cu-Mg aluminum alloys, which seriously reduce the lifetime of aircraft structural parts. In this paper, the microstructure and the intergranular corrosion behavior of 2024 alloy with varying Cu and Mg content were studied by using [...] Read more.

Intergranular corrosion is the main corrosion type of Al-Cu-Mg aluminum alloys, which seriously reduce the lifetime of aircraft structural parts. In this paper, the microstructure and the intergranular corrosion behavior of 2024 alloy with varying Cu and Mg content were studied by using a scanning electron microscope (SEM), transmission electron microscope (TEM), and three-dimensional atom probe (3DAP). The results show that nano-scale θ (Al₂Cu) and S (Al₂CuMg) particles precipitate along grain boundaries after quenching. The nano-cluster is the main strengthening phase in the 2024 alloy after natural aging for 96 h. The intergranular corrosion susceptibility is greatly affected by the presence of θ (Al₂Cu) and S (Al₂CuMg) phases along grain boundaries. Specifically, Cu-rich precipitates and intermetallics are known to act as local cathodes, which facilitates the action of oxygen reduction and ultimately drives anodic dissolution of the surrounding matrix material. The intergranular corrosion resistance of the alloy decreases with the increase in Cu and Mg contents. The alloy with a lower Mg content shows better corrosion resistance than the commonly used one with a Cu to Mg mass ratio of 2.9. The relationship between the observed corrosion behavior and various contents of Cu and Mg elements is discussed, which has potential to benefit the composition design of 2xxx aluminum alloy with high corrosion resistance. Full article

(This article belongs to the Special Issue Progress in Light Alloys)

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Review

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13 pages, 834 KiB

Open AccessReview

Possibility of Phase Transformation of Al₂O₃ by a Laser: A Review

by Tadas Matijošius, Juozas Padgurskas and Gedvidas Bikulčius

Crystals 2024, 14(5), 415; https://doi.org/10.3390/cryst14050415 (registering DOI) - 28 Apr 2024

Viewed by 117

Abstract

Aluminum (Al) components of high quality often require an optimal ratio of lightness and favorable mechanical properties. In order to improve the physical-mechanical properties of Al, an aluminum oxide (Al₂O₃) film is usually formed on the surface of Al, [...] Read more.

Aluminum (Al) components of high quality often require an optimal ratio of lightness and favorable mechanical properties. In order to improve the physical-mechanical properties of Al, an aluminum oxide (Al₂O₃) film is usually formed on the surface of Al, which itself is characterized by high strength, hardness, corrosion resistance, and other technical properties. Unfortunately, depending on the conditions, the oxide film may be formed from different crystal phases on the Al surface, which are not always of desirable quality, i.e., the α-Al₂O₃ phase. The present review demonstrates that the properties of the Al₂O₃ film may be improved by Al processing with a laser beam according to the scheme: Al (Al alloy) → electrochemical anodizing → treatment with laser irradiation → α-Al₂O₃. Both Al substrate and the anodizing electrolyte affect the phase transformation of anodic Al₂O₃. Laser irradiation of the Al₂O₃ surface leads to high heating and cooling rates, which may promote the formation of a highly crystalline α-Al₂O₃ phase on anodic Al₂O₃. Full article

(This article belongs to the Special Issue Progress in Light Alloys)

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