Crystals

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14 pages, 2696 KiB

Open AccessArticle

The Effect of High-Temperature Annealing on the Magnetic and Structural Properties of (MnFePSi)-Based Glass-Coated Microwires

by Mohamed Salaheldeen, Valentina Zhukova, Julian Gonzalez and Arcady Zhukov

Crystals 2025, 15(4), 311; https://doi.org/10.3390/cryst15040311 - 27 Mar 2025

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Abstract

In this paper, the impact of annealing at different temperatures (973 K, 1073 K, and 1123 K for 1 h) on the magnetic and microstructural properties of MnFePSi-based glass-coated microwires is studied. Annealing significantly influences the magnetic and microstructural properties of Mn–Fe–P–Si glass-coated [...] Read more.

In this paper, the impact of annealing at different temperatures (973 K, 1073 K, and 1123 K for 1 h) on the magnetic and microstructural properties of MnFePSi-based glass-coated microwires is studied. Annealing significantly influences the magnetic and microstructural properties of Mn–Fe–P–Si glass-coated microwires. XRD analysis reveals that increasing the annealing temperature leads to a notable increase in the Fe₂P phase content, reaching a maximum at 1123 K, while simultaneously reducing the presence of secondary phases observed in the as-prepared sample. The reduction in secondary phases in Mn–Fe–P–Si-based microwires, grain size, and internal stress relaxation have a profound impact on their magnetic behavior. High coercivity values are observed in both the as-prepared and annealed samples. However, annealing at higher temperatures (1073 K and 1123 K) results in a significant reduction in coercivity, decreasing from 1200 Oe for the sample annealed at 973 K to 300 Oe and 150 Oe, respectively. In addition, the sample annealed at 1123 K for 1 h shows a notable paramagnetic behavior for loops measured from 200 K to 300 K. Meanwhile, the other samples show ferromagnetic behavior for all measured temperatures from 5 to 300 K. This study highlights the significant potential for tailoring and modifying various magnetic properties of Mn–Fe–P–Si glass-coated microwires, including metamagnetic phase transitions, magnetic behavior, and the control of magnetic response (hardness/softness). Such tailored properties make Mn–Fe–P–Si glass-coated microwires promising candidates for a wide range of applications. Full article

(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)

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14 pages, 59884 KiB

Open AccessArticle

Analysis of the Structure and Properties of Welded Joints Made from Aluminum Alloys by Electron Beam Welding (EBW) and Friction Stir Welding (FSW)

by Sonia Boczkal, Monika Mitka, Joanna Hrabia-Wiśnios, Bartłomiej Płonka, Marek St. Węglowski, Aleksandra Węglowska and Piotr Śliwiński

Crystals 2025, 15(3), 208; https://doi.org/10.3390/cryst15030208 - 22 Feb 2025

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Abstract

One of the new areas that requires extensive study of the structure and properties of welded joints is the heat-affected zone (HAZ). This issue is particularly important for new constructions made of aluminium alloys intended for battery housing for powering electric car engines. [...] Read more.

One of the new areas that requires extensive study of the structure and properties of welded joints is the heat-affected zone (HAZ). This issue is particularly important for new constructions made of aluminium alloys intended for battery housing for powering electric car engines. Modern welding methods, such as EBW and FSW, meet the requirements related to the high precision of the process and the quality of the welded joint itself. This article presents the results of an analysis of the structure and strengthening of the HAZ of chemically modified AlMgSi(Cu) alloys via EBW and FSW. Microstructural observation was performed via SEM for each welded joint to determine the morphology of the precipitates. In the HAZ, β-Mg₂Si, Q-Al,MgCu,Si and α-Al,Fe,Si (Mn,Cu) phases with larger sizes and rounded shapes were visible than they were directly in the weld made via the EBW method. The joints produced by the FSW method were characterised by a wide weld area and an irregular weld line. Analysis of the crystallographic orientation via EBSD and grain orientation spread (GOS) revealed differences in the shape of the grains and the degree of recrystallisation in the weld area between the FSW and EBW methods. The distributions of HB (FSW) hardness and HV (EBW) microhardness measurements revealed a slight decrease in hardening in the HAZ. In joints welded by both methods, the hardness of the welds for alloys with increased copper and chromium contents increased by approximately 5%. Full article

(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)

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18 pages, 8358 KiB

Open AccessArticle

Corrosion Behavior and Mechanism of High-Aluminum Inconel 625 in Chlorinated Salts

by Ying Wei, Junjia Cao, Yuehong Zheng, Haicun Yu, Penghui Yang and Peiqing La

Crystals 2025, 15(2), 144; https://doi.org/10.3390/cryst15020144 - 29 Jan 2025

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Abstract

Concentrated solar power plant (CSP) technology holds significant application value in the renewable energy sector for converting solar radiation into thermal and electrical energy. As a heat storage medium for next-generation solar thermal power stations, chloride salts exhibit strong corrosive effects on structural [...] Read more.

Concentrated solar power plant (CSP) technology holds significant application value in the renewable energy sector for converting solar radiation into thermal and electrical energy. As a heat storage medium for next-generation solar thermal power stations, chloride salts exhibit strong corrosive effects on structural components. To enhance corrosion resistance of the heated body in molten salt environments, Inconel 625 is modified by incorporating aluminum, which facilitates the formation of a protective oxide film. In this study, High-Aluminum Inconel 625, after cold rolling and solution treatment, was immersed in a NaCl-KCl-MgCl₂ eutectic chloride melt at 650 °C for 200 h. Post-corrosion analysis revealed the formation of an alumina layer on the surface, effectively mitigating corrosion. Increased aluminum content resulted in thicker alumina layers and the formation of oxidation products, such as Cr₂O₃, Fe₂O₃, MoO₂, and MgCr₂O₄ spinel structures, significantly enhancing the alloy’s corrosion resistance. The Inconel 625 cold-rolled plate with 5.31 wt% Al exhibited the best corrosion resistance (3510 μm/year), making it a promising candidate for use in next-generation CSP heat storage and exchange components. Full article

(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)

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14 pages, 2789 KiB

Open AccessArticle

Effect of Mn Doping on Microstructure and Corrosion Behavior of CoCuNiTi High-Entropy Alloy Coatings

by Mingxing Ma, Zhixin Wang, Chengjun Zhu, Ying Dong, Lixin Liu, Liang Zhao, Qingxue Cui, Dachuan Zhu and Deliang Zhang

Crystals 2025, 15(1), 29; https://doi.org/10.3390/cryst15010029 - 29 Dec 2024

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Abstract

Mn-doped CoCuNiTi HEACs were prepared on 45 carbon steel substrate by laser cladding. CoCuNiTi and CoCuMnNiTi HEACs are dual-phase structures composed of FCC and BCC. The addition of Mn causes a decrease in the lattice constant and cell volume of the above two [...] Read more.

Mn-doped CoCuNiTi HEACs were prepared on 45 carbon steel substrate by laser cladding. CoCuNiTi and CoCuMnNiTi HEACs are dual-phase structures composed of FCC and BCC. The addition of Mn causes a decrease in the lattice constant and cell volume of the above two phases, as well as an increase in the density of the two phases and the FCC phase content. The microstructures of the two alloys are the typical dendritic structures. Ti and Co elements are enriched in the dendrite region; Cu element is enriched in the interdendrite region; the distribution of Mn is the most uniform in the dendrite and interdendrite regions. The addition of Mn element causes the microstructure to be significantly refined, and the width of the primary dendrite is reduced from 8.10 μm to 4.11 μm. CoCuNiTi alloy belongs to activation dissolution, and the Mn-containing alloy exhibits an obvious passivation zone. The addition of Mn element increases the capacitive reactance arc radius and the maximum phase angle of the alloy, indicating that the corrosion resistance of the Mn-containing alloy is significantly improved. Full article

(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)

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23 pages, 12491 KiB

Open AccessArticle

Effects of Copper Content and Thermo-Mechanical Treatment on Microstructure and Mechanical Properties of AlMgSi(Cu) Alloys

by Sonia Boczkal, Piotr Korczak, Konrad Żyłka, Kamila Limanówka, Bartłomiej Płonka, Krzysztof Remsak, Wojciech Szymański and Dariusz Leśniak

Crystals 2024, 14(12), 1027; https://doi.org/10.3390/cryst14121027 - 27 Nov 2024

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Abstract

This study presents the results of research on the influence of different contents of copper in aluminium alloys based on the 6xxx series on mechanical and structural properties. The investigation started with the alloying, and casting four billet variants with different copper content—0.8% [...] Read more.

This study presents the results of research on the influence of different contents of copper in aluminium alloys based on the 6xxx series on mechanical and structural properties. The investigation started with the alloying, and casting four billet variants with different copper content—0.8% Cu; 2B—1% Cu; 3A—1.2% Cu; and 3B—1.4% Cu. The prepared materials were homogenised and extruded on a 500T horizontal press with two different process temperatures and ram speeds ranging from 1 mm/s to 9 mm/s. After heat treating to the T6 and T5 tempers, their mechanical properties were tested. On this basis, the two most promising alloys 2A and 3B were selected and subjected to further tests. After extrusion and heat treatment of the profiles (to F, T1, T2, T5, and T5510), their mechanical properties were determined to select the preferred process parameters. Finally, a structural test based on crystallographic orientation based on the EBSD technique and TEM observations allowed for the characterisation of grain size, dispersoids, and phase analysis. Bright-field (BF) analysis allowed us to compare the deformed areas for T1, T5, and T5510 temperatures. The results showed significant growth in the mechanical properties of all the subjected alloys, and the best properties were shown for a Cu content of 1.4% with a tensile strength of 460 MPa and an elongation of 16% (T5510 tempering). The structural test showed an average grain size of 18 µm to 23 µm and solid solution decomposition differences for different heat-treating parameters. Full article

(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)

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15 pages, 6145 KiB

Open AccessArticle

Hierarchical Nanostructured Copper by Dealloying MnCu Alloy Ribbon for High-Performance Glucose Sensing

by Jinyi Wang, Bowen Fan, Jiana Song, Chen Chen, Yuan Ji and Jincheng Yu

Crystals 2024, 14(12), 1024; https://doi.org/10.3390/cryst14121024 - 26 Nov 2024

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Abstract

Electrochemical glucose sensing is vital for biomedical applications, particularly in diabetes management and continuous health monitoring. Among electrochemical sensors, non-enzyme-based sensors offer advantages such as cost-effectiveness, robust anti-interference capabilities, and environmental stability compared to enzyme-based ones. This study focuses on the development of [...] Read more.

Electrochemical glucose sensing is vital for biomedical applications, particularly in diabetes management and continuous health monitoring. Among electrochemical sensors, non-enzyme-based sensors offer advantages such as cost-effectiveness, robust anti-interference capabilities, and environmental stability compared to enzyme-based ones. This study focuses on the development of non-enzyme-based glucose sensors utilizing hierarchical nanostructured copper (Cu) electrodes. The electrodes are fabricated by selectively dissolving components from an alloy precursor. Specifically, MnCu alloy ribbons prepared by melt rolling were used due to their favorable properties, and electrochemical dealloying was employed to create nanostructured Cu with high electrocatalytic activity for glucose oxidation. Three-dimensional bicontinuous nanoporous copper with an average pore size of 34 nm~86 nm and an average ligament size range of 45 nm~125 nm can be obtained. The optimized hierarchical nanostructured Cu electrodes exhibited excellent performance, including high sensitivity (0.652 mA·mM⁻¹·cm⁻²), a wide linear detection range (0.001 mM to 1.5 mM), a low detection limit (0.73 μM), and a rapid response time. This work demonstrates the potential of nanostructured Cu in the advancement of non-enzyme-based glucose sensors. Full article

(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)

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12 pages, 5853 KiB

Open AccessArticle

Crystallographic Orientation of Grains Formed in the Laser Melt-Pool of (CoCuFeZr)₁₇Sm₂ Anisotropic Permanent Magnets

by Felix Trauter, Ralf Loeffler, Gerhard Schneider and Dagmar Goll

Crystals 2024, 14(11), 955; https://doi.org/10.3390/cryst14110955 - 31 Oct 2024

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Abstract

Textured microstructures and anisotropic properties are key factors for the optimization of magnetic materials. Only for high texture grades can the remanence J_r and the maximum energy product (BH)_max be maximized. In additive manufacturing such as laser powder bed fusion (PBF-LB), [...] Read more.

Textured microstructures and anisotropic properties are key factors for the optimization of magnetic materials. Only for high texture grades can the remanence J_r and the maximum energy product (BH)_max be maximized. In additive manufacturing such as laser powder bed fusion (PBF-LB), methods to achieve texture have to be developed. In this work, anisotropic (CoCuFeZr)₁₇Sm₂ sintered magnets have been used as a substrate in experiments featuring single laser tracks to study the relationships between crystallographic orientation of the substrate grains and crystallographic orientation of grain growth in the melt-pool. The <0001> crystal direction (c-axis) of the substrate has been systematically varied with respect to the orientation of the laser scan track on the specimen surface. Crystallographic orientations of the melt-pool and the substrate have been analyzed using electron backscatter diffraction (EBSD). It is found that if the c-axis is oriented perpendicular to the temperature gradient in the melt-pool, grains grow with orientation similar to that of the substrate grain. If the c-axis and the temperature gradient are oriented in the same direction, the grains grow with high misorientation to the substrate. The highest anisotropy in the melt-pool is achieved when the substrate’s c-axis is oriented along the laser scan track. Under these conditions, 98.7% of the melt-pool area shows a misorientation <45° compared to the substrate orientation. The texture grade of the melt-pool area is comparable to that of the substrate magnet, at 91.8% and 92.2%, respectively. Full article

(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)

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13 pages, 18696 KiB

Open AccessArticle

Effect of Primary γ′ Phase on High-Temperature Endurance Performance of GH4720Li Superalloy

by Xing Zhou, Ruifeng Dong, Yuchang Xie, Shuoqi Hu, Tianyuan Xu, Jian Li and Wei Zhang

Crystals 2024, 14(10), 851; https://doi.org/10.3390/cryst14100851 - 28 Sep 2024

Viewed by 1145

Abstract

To investigate the effect of the primary γ′ phase on the high-temperature endurance performance of GH4720Li superalloy, samples with different volume fractions of the primary γ′ phase were prepared by adjusting the heat treatment process. The high-temperature endurance performance was tested, and the [...] Read more.

To investigate the effect of the primary γ′ phase on the high-temperature endurance performance of GH4720Li superalloy, samples with different volume fractions of the primary γ′ phase were prepared by adjusting the heat treatment process. The high-temperature endurance performance was tested, and the microstructure was examined. Results indicate that samples with a higher volume fraction of the γ′ phase exhibit a greater stress rupture life. Additionally, alloy samples with varying γ′ phase volume fractions show improved plasticity and toughness at 760 °C/530 MPa. Fracture morphology results reveal that high-volume-fraction primary γ′ phase samples primarily undergo transgranular fracture, whereas low-volume-fraction samples exhibit intergranular fracture due to grain boundary sliding. During high-temperature endurance, the secondary γ′ phase in the crystal is affected. Long-term aging refines the secondary γ′ phase, resulting in a more uniform distribution. Finally, the influence of the primary γ′ phase and the creep behavior of each material group on high-temperature endurance performance are discussed. Full article

(This article belongs to the Special Issue Recent Advances in Microstructure and Properties of Metals and Alloys)

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