Editorial

4 pages, 164 KiB

Open AccessEditorial

Crystallography and Applications of Metallic Materials

by Joan-Josep Suñol

Metals 2024, 14(1), 89; https://doi.org/10.3390/met14010089 - 11 Jan 2024

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Scientific and technological interest in metals, metallic alloys and compounds is related to the wide range of applications in fields such as mobility, biomedicine, heat transfer, energy and sustainability [...] Full article

(This article belongs to the Special Issue Feature Papers in Crystallography and Applications of Metallic Materials)

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22 pages, 8628 KiB

Open AccessCommunication

Crystal Orientation and Dislocation Slip

by Malcolm Griffiths

Metals 2023, 13(12), 1950; https://doi.org/10.3390/met13121950 - 28 Nov 2023

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Abstract

It is a widely held belief that dislocation slip has a direct effect on crystal orientation. Some of the confusion may be attributed to semantics when researchers are referring to related effects of dislocations on crystal orientation; either elastic bending due to constraints [...] Read more.

It is a widely held belief that dislocation slip has a direct effect on crystal orientation. Some of the confusion may be attributed to semantics when researchers are referring to related effects of dislocations on crystal orientation; either elastic bending due to constraints or the creation of geometrically necessary dislocations by climb. This communication highlights the distinction between the two and discusses why what is often imagined conflicts with what is real and possible. It is demonstrated that deformation-induced changes in the orientation of crystals are primarily limited to twinning and collections of geometrically necessary dislocations (GNDs), which in the most extreme cases are sub-grain boundaries. Alternate explanations for texture changes related to dislocation slip are provided, and they challenge the notion that grains can simply rotate because of dislocation slip through some undefined mechanism. Full article

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11 pages, 4226 KiB

Open AccessArticle

Structural, Magnetocaloric, and Magnetic Properties in Heusler Ni₅₀Mn₃₅In₁₀X₅ (X = Ga, Fe and Al) Alloys

by Tarek Bachagha, Ramki Chakaravarthy, Wei Ren, Joan Saurina and Joan-Josep Suñol

Metals 2023, 13(12), 1913; https://doi.org/10.3390/met13121913 - 21 Nov 2023

Cited by 1 | Viewed by 752

Abstract

The structural, magnetocaloric, and magnetic characteristics in Heusler Ni₅₀Mn₃₅In₁₀X₅ (X = Ga, Fe, and Al) alloys were examined using X-ray diffraction and field-dependent magnetization measurements. All samples exhibited a mixture structure of cubic L2₁ and [...] Read more.

The structural, magnetocaloric, and magnetic characteristics in Heusler Ni₅₀Mn₃₅In₁₀X₅ (X = Ga, Fe, and Al) alloys were examined using X-ray diffraction and field-dependent magnetization measurements. All samples exhibited a mixture structure of cubic L2₁ and tetragonal L1₀ and underwent second-order magnetic transitions at T_C(Al5) = 220 K, T_C(Ga5) = 252 K, and T_C(Fe5) = 298 K. The Ga5 alloy exhibited structural change as indicated by a thermal hysteresis that may be seen in the saturation magnetic field in the M(T) dependences. The transition at the T_C point from a ferromagnetic to a paramagnetic state caused a drop in magnetization, supported by thermal hysteresis, at a low magnetic field (0.01 T). On the other hand, the Fe5 alloy presented a gradual decrease in magnetization with similar hysteresis behavior, also at a low magnetic field (0.01 T), whereas at 0.1 T of field, no features characteristic of this transition were detected. This could be due to a large difference in the metallic radius of Fe compared to that of In. Otherwise, magnetic investigations demonstrated that the replacement of In with Al may cause the structural transformation temperatures and T_C to be shifted to low temperatures. The present results imply that the structural transformation temperatures and the transition itself are highly dependent on chemical composition. Furthermore, under a magnetic field change of 5 T, the maximum magnetic entropy changes of 0.6 J/kg K, 1.4 J/kg K, and 2.71 J/kg K for the Ga5, Fe5, and Al5 alloys, respectively, were determined by their T_C. Refrigeration capacity values were found to be 25 J/kg, 74 J/kg, and 98 J/kg at µ₀∆H = 5 T. These ribbons are viable candidates for multifunctional applications due to their cheaper cost and their physical characteristics disclosed during the magnetostructural transition, which takes place close to the room temperature. Full article

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10 pages, 6133 KiB

Open AccessArticle

Effect of Barnacles on the Corrosion Behavior of 304 Stainless Steel

by Peichang Deng, Juyu Shangguan, Jiezhen Hu, Baoyu Geng and Peilin Wang

Metals 2023, 13(10), 1649; https://doi.org/10.3390/met13101649 - 26 Sep 2023

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Abstract

Wire-beam, potentiodynamic polarization, electrochemical impedance spectroscopy and surface corrosion morphology analysis techniques were used to investigate the corrosion characteristics of 304 stainless steel (304SS) specimens subjected to different degrees of fouling; these analyses were conducted to clarify the corrosive effects of biofilms and [...] Read more.

Wire-beam, potentiodynamic polarization, electrochemical impedance spectroscopy and surface corrosion morphology analysis techniques were used to investigate the corrosion characteristics of 304 stainless steel (304SS) specimens subjected to different degrees of fouling; these analyses were conducted to clarify the corrosive effects of biofilms and barnacles. The experimental results indicated that the gradual thickening of the biofilm reduces the corrosion rate of 304SS (I_corr = 0.0677 μA/cm²). Mature biofilm acts as a barrier and significantly increases the protection of the substrate (Z = 905,000 Ω·cm²). The corrosion mechanisms of 304SS fouled with barnacles at various stages of growth are distinct: the corrosion rates of the microelectrodes fouled by living and recently dead barnacles are low because the overall structure is still intact. This structure creates a closed environment between the barnacles and the metal, limiting the transfer of corrosive factors from the outside to the inside. Despite the influences of corrosive bacterial decomposition, the E_corr values of recently dead barnacles dramatically decrease to −668.8 mV. The microelectrode covered by the empty-shell barnacles corrodes heavily. Bacteria decompose the barnacle body and calcite shell, and glue damages their originally closed structures. Direct contact between the metal and reactive ions occurs, resulting in the continuous ingress of Cl⁻ into the cracks, which intensifies crevice corrosion. Full article

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15 pages, 7262 KiB

Open AccessArticle

Particle Stimulated Nucleation Effect for Al-Mg-Zr-Sc Alloys with Ni Addition during Multidirectional Forging

by Mikhail S. Kishchik, Andrey G. Mochugovskiy, Maxence Cuda, Anna A. Kishchik and Anastasia V. Mikhaylovskaya

Metals 2023, 13(8), 1499; https://doi.org/10.3390/met13081499 - 21 Aug 2023

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Abstract

The study aims to investigate the influence of fraction of coarse undeformed particles on the microstructure evolution and mechanical properties of alloys processed by isothermal multidirectional forging (MDF). For this purpose, Al-Mg-Ni-Sc-Zr-based alloys with different Ni concentrations and a fraction of Al₃ [...] Read more.

The study aims to investigate the influence of fraction of coarse undeformed particles on the microstructure evolution and mechanical properties of alloys processed by isothermal multidirectional forging (MDF). For this purpose, Al-Mg-Ni-Sc-Zr-based alloys with different Ni concentrations and a fraction of Al₃Ni particles of solidification origin phase were subjected to MDF at 350 °C. Precipitates of the L1₂-structured Al₃(Sc,Zr) phase retained their structure, morphology, and size after MDF and were coherent with the aluminum matrix. The Al₃Ni phase particles stimulated the nucleation of recrystallized grains and contributed significantly to the formation of an ultrafine-grained structure. The uniformity of the grain structure increased, and the average grain size decreased with an increase in the fraction of Al₃Ni particles. A fine-grained structure with a mean grain size of 2.4–3.4 µm was observed after MDF with a cumulative strain of 12. The results demonstrate that a bimodal particles size distribution with a volume fraction of nanoscale f~0.1% and microscale f~8% particles provided for the formation of a homogenous fine-grained structure after MDF and improved the mechanical properties. Full article

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11 pages, 3905 KiB

Open AccessArticle

The Influence of Powder Particle Size Distributions on Mechanical Properties of Alloy 718 by Laser Powder Bed Fusion

by Benjamin Thomas Stegman, Jack Lopez, William Jarosinski, Haiyan Wang and Xinghang Zhang

Metals 2023, 13(8), 1384; https://doi.org/10.3390/met13081384 - 01 Aug 2023

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Abstract

Currently, metallic powders for laser powder bed fusion (LPBF) primarily come in two commercially available powder size distributions (PSDs): 15+/45− for non-reactive powders and 15+/63− for reactive powders. These powders are generally produced via gas atomization processes that create highly spherical particles with [...] Read more.

Currently, metallic powders for laser powder bed fusion (LPBF) primarily come in two commercially available powder size distributions (PSDs): 15+/45− for non-reactive powders and 15+/63− for reactive powders. These powders are generally produced via gas atomization processes that create highly spherical particles with a Gaussian PSD. Because of the standard deviation within a Gaussian distribution, only small portions of the total product are used for LPBF applications. This screening process makes the other particle sizes a waste product and, thus, increases processing costs. The non-reactive 718 powder was printed with both the typical PSD of 15+/45− and a wider bimodal experimental PSD. Compared to conventional 718, the 718 alloys with bimodal PSD shows less than a 0.2% difference in density, and insignificant change in mechanical behavior. Electron backscattered diffraction studies revealed that grain sizes and morphology were similar between the two sample sets, but bimodal 718 alloy has a slightly greater degree of large grains. The study suggests that particles with wide or bimodal size distributions show promise in producing equivalent high-quality products without sacrificing mechanical properties. Full article

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12 pages, 3332 KiB

Open AccessArticle

Study of Microstructure and Mechanical Properties of Electrodeposited Cu on Silicon Heterojunction Solar Cells

by Jeff Shan, Chung-Hsuan Shan, Craig Huang, Yu-Ping Wu, Yuan-Kai Lia and Wen-Jauh Chen

Metals 2023, 13(7), 1223; https://doi.org/10.3390/met13071223 - 02 Jul 2023

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Abstract

This study investigated the use of a pure copper seed layer to improve the adhesion strength and reduce the residual stress of electroplated copper films for heterojunction technology in crystalline solar cells. The experiment involved depositing a copper seed layer and an indium [...] Read more.

This study investigated the use of a pure copper seed layer to improve the adhesion strength and reduce the residual stress of electroplated copper films for heterojunction technology in crystalline solar cells. The experiment involved depositing a copper seed layer and an indium tin oxide (ITO) layer on textured silicon using sputtering. This resulted in the formation of a Cu(s)/ITO/Si structure. Following this step, a 10 µm thick copper layer was electroplated onto the Cu(s)/ITO/Si structure. Various characterization techniques were employed to evaluate the electroplated copper films’ microstructures, residual stress, and adhesion strength. The microstructures of the films were examined using a scanning transmission electron microscope (STEM), revealing a twin structure with a grain size of approximately 1 µm. The residual stresses of the as-deposited and annealed samples were measured using an X-ray diffractometer (XRD), yielding values of 76.4 MPa and 49.1 MPa, respectively. The as-deposited sample exhibited higher tension compared to the annealed sample. To assess the adhesion strength of the electroplated copper films, peel-off tests were conducted at a 90° angle with a constant speed of 30 mm/min. The peel force, measured in units of N/mm, was similar for both the as-deposited and annealed samples. Specifically, the peel force for electroplating copper on the copper seed layer on the ITO was determined to be 2.6 N/mm for the maximum value and 2.25 N/mm for the average value. This study demonstrated that using a pure copper seed layer during electroplating can improve adhesion strength and reduce residual stress in copper films for heterojunction technology in crystalline solar cells. These findings contribute to the development of more reliable and efficient solar-cell-manufacturing processes. Full article

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14 pages, 5811 KiB

Open AccessArticle

Phase Transformation Crystallography in Pipeline HSLA Steel after TMCP

by Mikhail L. Lobanov, Maria A. Zorina, Maxim S. Karabanalov, Nikolay V. Urtsev and Andrey A. Redikultsev

Metals 2023, 13(6), 1121; https://doi.org/10.3390/met13061121 - 15 Jun 2023

Cited by 1 | Viewed by 1314

Abstract

Thermo-mechanical controlled processing (TMCP) is employed to obtain the required level of mechanical properties of contemporary high-strength low-alloy (HSLA) steel plates utilized for gas and oil pipeline production. The strength, deformation behavior and resistance to the formation and propagation of running fractures of [...] Read more.

Thermo-mechanical controlled processing (TMCP) is employed to obtain the required level of mechanical properties of contemporary high-strength low-alloy (HSLA) steel plates utilized for gas and oil pipeline production. The strength, deformation behavior and resistance to the formation and propagation of running fractures of the pipeline steel are mainly determined by its microstructure and crystallographic texture. These are formed as a result of austenite deformation and consequent γ→α-transformation. This present study analyses the crystallographic regularities of the structural and textural state formation in a steel plate that has been industrially produced by means of TMCP. The values of the mechanical properties that have been measured in different directions demonstrate the significance of the crystallographic texture in the deformation and failure of steel products. An electron backscatter diffraction (EBSD) method and crystallographic analysis were utilized to establish the connection between the main texture components of the deformed austenite and α-phase orientations. This paper demonstrates that the crystallographic texture that is formed due to a multipath γ→α-transformation results from the α-phase nucleation on the special boundaries between grains with γ-phase orientations. The analysis of the spectra of the α-γ-interface boundary angle deviations from the Kurdjumov–Sachs (K–S), Nishiyama–Wassermann (N–W), and Greninger–Troiano (G–T) orientation relationships (ORs) allows to suggest that the observed austenite particles represent a secondary austenite (not retained) that precipitates at intercrystalline α-phase boundaries and correspond to the ORs with regard to only one adjacent crystallite. Full article

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13 pages, 4570 KiB

Open AccessArticle

Influence of a Protective Coating on the Crystallization of an Amorphous Fe₇₈Si₁₃B₉ Alloy

by Galina Abrosimova, Valentina Chirkova, Danila Matveev, Elena Pershina, Nikita Volkov and Alexandr Aronin

Metals 2023, 13(6), 1090; https://doi.org/10.3390/met13061090 - 08 Jun 2023

Cited by 2 | Viewed by 1142

Abstract

The effect of free volume on the crystallization of amorphous Fe₇₈Si₁₃B₉ ribbons was studied using ultrasonic and thermal treatments. To maintain free volume under heating, amorphous samples were coated with a special protective Ta coating. It has been [...] Read more.

The effect of free volume on the crystallization of amorphous Fe₇₈Si₁₃B₉ ribbons was studied using ultrasonic and thermal treatments. To maintain free volume under heating, amorphous samples were coated with a special protective Ta coating. It has been shown via X-ray diffraction that the fraction of the crystalline phase in the annealed coated amorphous ribbons is higher than in the corresponding uncoated samples. The use of ultrasonic treatment and the application of a protective coating lead to the formation of a larger proportion of the crystalline phase during annealing. Differences in crystallization kinetics are discussed under the assumption that the concentration of free volume in amorphous samples affects their crystallization, as well as the role of the Ta coating preventing the release of free volume to the surface during heat treatment. Full article

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13 pages, 3851 KiB

Open AccessArticle

Reorientation Mechanisms of Graphene Coated Copper {001} Surfaces

by Jian Song, Songsong Yao, Quan Li, Jiamiao Ni, Zhuoxin Yan, Kunming Yang, Guisen Liu, Yue Liu and Jian Wang

Metals 2023, 13(5), 910; https://doi.org/10.3390/met13050910 - 08 May 2023

Cited by 4 | Viewed by 1542

Abstract

Engineering the surface orientation of face-centered cubic (fcc) metals to the close-packed {111} plane can significantly enhance their oxidation resistance. However, owing to the synergetic effect of surface energy density (

\dot{γ}

) and strain energy density (

ω

), such close-packed [...] Read more.

Engineering the surface orientation of face-centered cubic (fcc) metals to the close-packed {111} plane can significantly enhance their oxidation resistance. However, owing to the synergetic effect of surface energy density (

\dot{γ}

) and strain energy density (

ω

), such close-packed surface orientation can currently only be achieved by atomic-level thin film epitaxy or monocrystallization of polycrystalline metals. In this study, we characterized the microstructures of pure copper (Cu) foil and two types of graphene-coated Cu (Gr/Cu) foils and observed a 12~14 nm thick reconstructed surface layer with the {111} orientation in the high-temperature deposited Gr/{001} Cu surface. Combining the statistical results with thermodynamic analysis, we proposed a surface melting-solidification mechanism for the reconstruction of the Cu surface from {001} orientation to {111} orientation. This process is dominated by Gr/Cu interfacial energy and is particularly promoted by high-temperature surface melting. We also validated such a mechanism by examining Cu surfaces coated by h-BN (hexagonal boron nitride) and amorphous carbon. Our findings suggest a possible strategy to enhance the surface properties of fcc metals via engineering surface crystallography. Full article

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14 pages, 1130 KiB

Open AccessArticle

Effect of Annealing on the Magnetic Properties of Co₂MnSi-Based Heusler Alloy Glass-Coated Microwires

by Mohamed Salaheldeen, Mihail Ipatov, Paula Corte-Leon, Valentina Zhukova and Arcady Zhukov

Metals 2023, 13(2), 412; https://doi.org/10.3390/met13020412 - 16 Feb 2023

Cited by 8 | Viewed by 1334

Abstract

In the current study, we concentrated on the influence of annealing on the magnetic behavior of Co₂MnSi-based Heusler microwires. We set the annealing temperature at 1023 K for 2 h, as the sample did not show any significant changes in the [...] Read more.

In the current study, we concentrated on the influence of annealing on the magnetic behavior of Co₂MnSi-based Heusler microwires. We set the annealing temperature at 1023 K for 2 h, as the sample did not show any significant changes in the magnetic properties at lower temperatures, while annealing at temperatures above 1023 K damages the glass coating. Strong in-plane magnetocrystalline anisotropy parallel to the microwire axis was evident in the magnetic behavior at room temperature for as-prepared and annealed samples. The coercivity of the annealed sample was four times higher than that of the as-prepared sample across a wide range of measuring temperatures. Both annealed and as-prepared samples exhibit quite stable coercivity behavior with temperature, which may have interesting applications. The an nealed sample did not exhibit magnetic saturation for M-H loops measured below 50 K. Sharp irreversible magnetic behavior has been detected for annealed samples at a blocking temperature of 220 K; at the same time, the blocking temperature for the as-prepared sample was 150 K. The strong internal mechanical stress induced during the fabrication of Co₂MnSi microwires in addition to the internal stress relaxation caused by the annealing induced the onset of magnetic phases resulting in unusual and irreversible magnetic behavior. Full article

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7 pages, 5769 KiB

Open AccessArticle

Influence of Neutron Irradiation on Microstructure and Mechanical Properties of Coarse- and Ultrafine-Grained Titanium Grade 2

by Pavel Zháňal, Tomáš Krajňák, Mariia Zimina, Alica Fedoriková, Ondřej Srba, Petr Harcuba, Josef Stráský and Miloš Janeček

Metals 2022, 12(12), 2180; https://doi.org/10.3390/met12122180 - 18 Dec 2022

Cited by 1 | Viewed by 1374

Abstract

The influence of neutron irradiation on the microstructure and related mechanical properties of Ti Grade 2 in coarse- and ultrafine-grained conditions was investigated. It was found that mechanical properties of the coarse-grained (CG) state were significantly affected by neutron irradiation. At room temperature [...] Read more.

The influence of neutron irradiation on the microstructure and related mechanical properties of Ti Grade 2 in coarse- and ultrafine-grained conditions was investigated. It was found that mechanical properties of the coarse-grained (CG) state were significantly affected by neutron irradiation. At room temperature (RT), the yield stress increased by more than 30%, whereas the ductility decreased by more than 50%. An even bigger difference in the mechanical properties between irradiated and non-irradiated states was observed at a temperature of 300 °C. Changes in the mechanical properties can be attributed to the high density of defect clusters/dislocation loops induced by neutron irradiation. On the other hand, the ultrafine-grained (UFG) state is more resistant to radiation damage. The mechanical properties at RT did not change upon neutron radiation, while at a temperature of 300 °C, the yield stress increased only by about 10%. Enhanced radiation resistance of the UFG state can be attributed to the presence of a high density of dislocations and dense network of high-angle grain boundaries, which act as traps for radiation-induced defects and, thus, prevent the accumulation of these defects in the microstructure. Full article

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10 pages, 2652 KiB

Open AccessArticle

Austenite Formation in the Oxidized Layer of Ultra-High-Strength 13Ni15Co10Mo Maraging Steel

by Daniela P. M. da Fonseca, Leandro G. de Carvalho, Nelson B. de Lima and Angelo F. Padilha

Metals 2022, 12(12), 2115; https://doi.org/10.3390/met12122115 - 09 Dec 2022

Cited by 2 | Viewed by 1268

Abstract

Maraging steels are precipitation hardening alloys that can achieve an ultra-high yield strength (~3 GPa), however associated with low toughness. During exposure to high temperatures, an oxidation process occurs on the surface of these steels, generally, the oxides formed are hematite and/or magnetite. [...] Read more.

Maraging steels are precipitation hardening alloys that can achieve an ultra-high yield strength (~3 GPa), however associated with low toughness. During exposure to high temperatures, an oxidation process occurs on the surface of these steels, generally, the oxides formed are hematite and/or magnetite. The aim of this study was to investigate oxidation on a maraging 13Ni15Co10Mo at annealing temperature of 900 °C. The bulk microstructure was investigated by several complementary techniques and the oxidized surface was characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD). The results showed that the bulk microstructure, at annealed condition, consists of a lath martensite with a hardness of round 400 HV. The most external and oxidized surface contains the oxides hematite, magnetite and kamiokite. Finally, the presence of austenite was detected in the first 2 μm below the surface. Chemical microanalysis indicated that the austenite is stable at room temperature in this region due a composition gradient that makes this region rich in nickel and cobalt. The composition gradient is due atom diffusion during oxides formation. Austenite near to the surface is very convenient as it could avoid crack initiation and propagation, improving toughness. Full article

(This article belongs to the Special Issue Feature Papers in Crystallography and Applications of Metallic Materials)

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