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Characterization of Metallic Materials: Microstructure, Forming, and Heat Treatment

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Metals and Alloys".

Deadline for manuscript submissions: closed (20 February 2024) | Viewed by 15784

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Industrial Materials and Process R&D Department, Korea Institute of Industrial Technology (KITECH), Incheon 21999, Republic of Korea
Interests: metals and alloys; thermodynamic calculation; phase diagram; solidification; metal oxidation
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Guest Editor
Industrial Materials and Process R&D Department, Korea Institute of Industrial Technology, Incheon, Republic of Korea
Interests: alloy; magnesium alloys; thermooxidation; oxidation

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Guest Editor
Industrial Materials and Process R&D Department, Korea Institute of Industrial Technology, Incheon, Republic of Korea
Interests: materials; material characterization; mechanical properties; materials engineering; alloys

Special Issue Information

Dear Colleagues,

This Special Issue features research and review articles on characterization of metallic materials in various material behaviors such as solidification, forming, and heat treatment. This issue focuses on all characterization methods, including all forms of microscopy (transmission electron microscope, scanning electron microscope, etc.) and analytical techniques on microstructure, interface, surface, etc. Studies focusing on analysis using computational science are also welcome. Recent studies dealing with the behavior of materials in various phenomena (solidification, phase transformation, oxidation, diffusion, deformation and so on) that can occur in processes such as casting, plastic working, and heat treatment are suitable for publication in this issue. This Special Issue will provide materials scientists with up-to-date information explaining the behavior of many types of metallic materials using novel approaches. This issue covers all kinds of metallic materials

Dr. Seong-Ho Ha
Prof. Dr. Shae-Kwang Kim
Dr. Hyun-Kyu Lim
Guest Editors

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Keywords

  • metals and alloys
  • microstructure characterization
  • microscopy
  • solidification
  • forming
  • heat treatment

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Published Papers (15 papers)

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Research

12 pages, 5474 KiB  
Communication
Towards Understanding {10-11}-{10-12} Secondary Twinning Behaviors in AZ31 Magnesium Alloy during Fatigue Deformation
by Yunxiang You, Li Tan, Yuqin Yan, Tao Zhou, Pengfei Yang, Jian Tu and Zhiming Zhou
Materials 2024, 17(7), 1594; https://doi.org/10.3390/ma17071594 - 31 Mar 2024
Viewed by 696
Abstract
Tensile-compression fatigue deformation tests were conducted on AZ31 magnesium alloy at room temperature. Electron backscatter diffraction (EBSD) scanning electron microscopy was used to scan the microstructure near the fatigue fracture surface. It was found that lamellar {10-11}-{10-12} secondary twins (STs) appeared inside primary [...] Read more.
Tensile-compression fatigue deformation tests were conducted on AZ31 magnesium alloy at room temperature. Electron backscatter diffraction (EBSD) scanning electron microscopy was used to scan the microstructure near the fatigue fracture surface. It was found that lamellar {10-11}-{10-12} secondary twins (STs) appeared inside primary {10-11} contraction twins (CTs), with a morphology similar to the previously discovered {10-12}-{10-12} STs. However, through detailed misorientation calibration, it was determined that this type of secondary twin is {10-11}-{10-12} ST. Through calculation and analysis, it was found that the matrix was under compressive stress in the normal direction (ND) during fatigue deformation, which was beneficial for the activation of primary {10-11} CTs. The local strain accommodation was evaluated based on the geometric compatibility parameter (m’) combined with the Schmid factor (SF) of the slip system, leading us to propose and discuss the possible formation mechanism of this secondary twin. The analysis results indicate that when the local strain caused by basal slip at the twin boundaries cannot be well transmitted, {10-11}-{10-12} STs are activated to coordinate the strain, and different loading directions lead to different formation mechanisms. Moreover, from the microstructure characterization near the entire fracture surface, we surmise that the presence of such secondary twins is not common. Full article
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16 pages, 13348 KiB  
Article
Corrosion Behavior of Homogenized and Extruded 1100 Aluminum Alloy in Acidic Salt Spray
by Yuchao Zhao, Qiang Lu, Qudong Wang, Dezhi Li, Feng Li and Yuzhao Luo
Materials 2024, 17(6), 1279; https://doi.org/10.3390/ma17061279 - 10 Mar 2024
Viewed by 919
Abstract
The 1100 aluminum alloy has been widely used in many industrial fields due to its high specific strength, fracture toughness, excellent thermal conductivity, and corrosion resistance. In this study, the corrosion behavior of the homogenized and hot-extruded 1100 aluminum alloy in acid salt [...] Read more.
The 1100 aluminum alloy has been widely used in many industrial fields due to its high specific strength, fracture toughness, excellent thermal conductivity, and corrosion resistance. In this study, the corrosion behavior of the homogenized and hot-extruded 1100 aluminum alloy in acid salt spray environment for different time was studied. The microstructure of the 1100 aluminum alloy before and after corrosion was characterized by an optical microscope (OM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and a laser scanning confocal microscope (LSCM). The difference in corrosion resistance between the homogenized and extruded 1100 aluminum alloy was analyzed via the electrochemical method. The results indicate that after hot extrusion at 400 °C, the microstructure of the 1100 aluminum alloy changes from an equiaxed crystal structure with (111) preferentially distributed in a fibrous structure with (220) preferentially distributed. There was no obvious dynamic recrystallization occurring during extrusion, and the second-phase particles containing Al-Fe-Si were coarse and unevenly distributed. With the increase in corrosion time, corrosion pits appeared on the surface of the 1100 aluminum alloy, and a corrosion product layer was formed on the surface of the homogenized 1100 aluminum alloy, which reduced the corrosion rate. After 96 h of corrosion, the CPR of the extruded samples was 0.619 mm/a, and that of the homogenized samples was 0.442 mm/a. The corrosion resistance of the extruded 1100 aluminum alloy was affected by the microstructure and the second phase, and no protective layer of corrosion products was formed on the surface, resulting in a faster corrosion rate and deeper corrosion pits. Full article
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11 pages, 6381 KiB  
Article
Impact of Electromagnetic Stirring Roller Arrangement Pattern on Magnetic Field Simulation and Solidification Structure of PW800 Steel in the Second Cooling Zone
by Zhixiang Xiao, Guifang Zhang, Daiwei Liu and Chenhui Wu
Materials 2024, 17(5), 1038; https://doi.org/10.3390/ma17051038 - 23 Feb 2024
Viewed by 633
Abstract
Strand electromagnetic stirring (S-EMS), a technique applied in the secondary cooling zone, enhances the solidification structure of casting slabs. This study examines how the arrangement pattern of electromagnetic stirring rollers—face-to-face, side-to-side or up-down misalignment produces this enhancement. It uses simulations to analyze the [...] Read more.
Strand electromagnetic stirring (S-EMS), a technique applied in the secondary cooling zone, enhances the solidification structure of casting slabs. This study examines how the arrangement pattern of electromagnetic stirring rollers—face-to-face, side-to-side or up-down misalignment produces this enhancement. It uses simulations to analyze the electromagnetic field distribution in these configurations. The findings demonstrate that: (1) The magnetic flux density distribution in the casting slab is related to the arrangement pattern of the electromagnetic stirring rollers. (2) The face-to-face arrangement produces the largest and most concentrated electromagnetic force compared to the other two arrangement patterns. (3) S-EMS can effectively improve the equiaxed grain ratio of casting slabs. Before and after EMS is turned on, casting slabs’ average equiaxed grain ratio goes up from 8% to 33%. Full article
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14 pages, 5863 KiB  
Article
Simulation and Experimental Study on the Effect of Superheat on Solidification Microstructure Evolution of Billet in Continuous Casting
by Nan Tian, Guifang Zhang, Peng Yan, Pengchao Li, Zhenhua Feng and Xiaoliang Wang
Materials 2024, 17(3), 682; https://doi.org/10.3390/ma17030682 - 31 Jan 2024
Cited by 1 | Viewed by 906
Abstract
The control of the solidification structure of a casting billet is directly correlated with the quality of steel. Variations in superheat can influence the transition from columnar crystals to equiaxed crystals during the solidification process, subsequently impacting the final solidification structure of the [...] Read more.
The control of the solidification structure of a casting billet is directly correlated with the quality of steel. Variations in superheat can influence the transition from columnar crystals to equiaxed crystals during the solidification process, subsequently impacting the final solidification structure of the billet. In this study, a model of microstructure evolution during billet solidification was established by combining simulation and experiment, and the dendrite growth microstructure evolution during billet solidification under different superheat was studied. The results show that when the superheat is 60 K, the complete solidification time of the casting billet from the end of the 50 mm section is 252 s, when the superheat is 40 K, the complete solidification time of the casting billet is 250 s, and when the superheat is 20 K, the complete solidification time of the casting billet is 245 s. When the superheat is 20 K, the proportion of the equiaxed crystal region is higher—the highest value is 53.35%—and the average grain radius is 0.84556 mm. The proportion of the equiaxed crystal region decreases with the increase of superheat. When the superheat is 60 K, the proportion of the equiaxed crystal region is the lowest—the lowest value is 46.27%—and the average grain radius is 1.07653 mm. Proper reduction of superheat can obviously reduce the size of equiaxed crystal, expand the area of equiaxed crystal and improve the quality of casting billet. Full article
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18 pages, 7938 KiB  
Article
The Construction of a Lattice Image and Dislocation Analysis in High-Resolution Characterizations Based on Diffraction Extinctions
by Kun Ni, Hanyu Wang, Qianying Guo, Zumin Wang, Wenxi Liu and Yuan Huang
Materials 2024, 17(3), 555; https://doi.org/10.3390/ma17030555 - 24 Jan 2024
Viewed by 1007
Abstract
This paper introduces a method for high-resolution lattice image reconstruction and dislocation analysis based on diffraction extinction. The approach primarily involves locating extinction spots in the Fourier transform spectrum (reciprocal space) and constructing corresponding diffraction wave functions. By the coherent combination of diffraction [...] Read more.
This paper introduces a method for high-resolution lattice image reconstruction and dislocation analysis based on diffraction extinction. The approach primarily involves locating extinction spots in the Fourier transform spectrum (reciprocal space) and constructing corresponding diffraction wave functions. By the coherent combination of diffraction and transmission waves, the lattice image of the extinction planes is reconstructed. This lattice image is then used for dislocation localization, enabling the observation and analysis of crystal planes that exhibit electron diffraction extinction effects and atomic jump arrangements during high-resolution transmission electron microscopy (HRTEM) characterization. Furthermore, due to the method’s effectiveness in localizing dislocations, it offers a unique advantage when analyzing high-resolution images with relatively poor quality. The feasibility of this method is theoretically demonstrated in this paper. Additionally, the method was successfully applied to observed edge dislocations, such as 1/6[211], 1/6[211], and 1/2[011], which are not easily observable in conventional HRTEM characterization processes, in electro-deposited Cu thin films. The Burgers vectors were determined. Moreover, this paper also attempted to observe screw dislocations that are challenging to observe in high-resolution transmission electron microscopy. By shifting a pair of diffraction extinction spots and superimposing the reconstructed images before and after the shift, screw dislocations with a Burgers vector of 1/2[011] were successfully observed in electro-deposited Cu thin films. Full article
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12 pages, 5236 KiB  
Article
Investigation of Solidification Heat Transfer in Slab Continuous Casting Process Based on Different Roll Contact Calculation Methods
by Daiwei Liu, Guifang Zhang, Jianhua Zeng and Chenhui Wu
Materials 2024, 17(2), 482; https://doi.org/10.3390/ma17020482 - 19 Jan 2024
Cited by 1 | Viewed by 849
Abstract
The heat transfer of a slab is significantly influenced by roll contact during the continuous casting process. The influence of roll contact calculation methods on the predicted heat transfer results has not been previously investigated. In this work, the non-uniform solidification of the [...] Read more.
The heat transfer of a slab is significantly influenced by roll contact during the continuous casting process. The influence of roll contact calculation methods on the predicted heat transfer results has not been previously investigated. In this work, the non-uniform solidification of the wide-thick slab was studied with a 2D heat transfer model using real roll contact method (R. method) and equivalent roll contact method (E. method). The predicted slab surface temperature and shell thickness were verified with the measured results of the infrared camera and nail shooting experiments, respectively. Then, the predicted heat transfer results (including the slab surface temperature, mushy region length, and solidification end position) for the wide-thick slab with different thicknesses and different casting speeds were calculated using the E. method and R. method, and the influence of these two roll contact methods on the predicted heat transfer results was discussed for the first time. The results show that both these two roll contact methods could be applied to accurately predict the slab surface temperature without considering the transient temperature dips in the roll–slab contact regions. However, the deviation of the predicted mushy region length and solidification end position using the E. method are obvious. Compared with the R. method, the predicted mushy region length obtained using the E. method is larger and the solidification end obviously subsequently moves along the casting direction. Full article
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19 pages, 11802 KiB  
Article
Microstructural Characteristics and Material Failure Mechanism of SLM Ti-6Al-4V-Zn Alloy
by Yi-Jin Cheng, Fei-Yi Hung and Jun-Ren Zhao
Materials 2023, 16(23), 7341; https://doi.org/10.3390/ma16237341 - 25 Nov 2023
Cited by 1 | Viewed by 880
Abstract
This study focuses on the additive manufacturing technique of selective laser melting (SLM) to produce Ti-6Al-4V-Zn titanium alloy. The addition of zinc at 0.3 wt.% was investigated to improve the strength and ductility of SLM Ti-6Al-4V alloys. The microstructure and mechanical properties were [...] Read more.
This study focuses on the additive manufacturing technique of selective laser melting (SLM) to produce Ti-6Al-4V-Zn titanium alloy. The addition of zinc at 0.3 wt.% was investigated to improve the strength and ductility of SLM Ti-6Al-4V alloys. The microstructure and mechanical properties were analyzed using different vacuum heat treatment processes, with the 800-4-FC specimen exhibiting the most favorable overall mechanical properties. Additionally, zinc serves as a stabilizing element for the β phase, enhancing the resistance to particle erosion and corrosion impedance of Ti-6Al-4V-Zn alloy. Furthermore, the incorporation of trace amounts of Zn imparts improved impact toughness and stabilized high-temperature tensile mechanical properties to SLM Ti-6Al-4V-Zn alloy. The data obtained serve as valuable references for the application of SLM-64Ti. Full article
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14 pages, 9534 KiB  
Article
Phase Stability and Slag-Induced Destabilization in MnO2 and CeO2-Doped Calcia-Stabilized Zirconia
by Hwanseok Lee, Hee-Seon Lee, Seonghoon Kim, Kanghee Jo, Ilguk Jo and Heesoo Lee
Materials 2023, 16(22), 7240; https://doi.org/10.3390/ma16227240 - 20 Nov 2023
Viewed by 791
Abstract
MnO2 and CeO2 were doped to improve the corrosion resistance of CSZ (calcia-stabilized zirconia), and we studied the phase formation, mechanical properties, and corrosion resistance by molten mold flux. The volume fraction of the monoclinic phase gradually decreased as the amount [...] Read more.
MnO2 and CeO2 were doped to improve the corrosion resistance of CSZ (calcia-stabilized zirconia), and we studied the phase formation, mechanical properties, and corrosion resistance by molten mold flux. The volume fraction of the monoclinic phase gradually decreased as the amount of MnO2 doping increased. The splitting phenomenon of the t(101) peak was observed in 2Mn_CSZ, and in 4Mn_CSZ, it was completely split, forming a cubic phase. The relative density increased and the monoclinic phase decreased as the doping amount increased, leading to an increase in Vickers hardness and flexural strength. However, in 3Mn_CSZ and 4Mn_CSZ, where cubic phase formation occurred, the tetragonal phase decreased, leading to a reduction in these properties. MnO2-doped CSZ exhibited a larger fraction of the monoclinic phase compared to the original CSZ after the corrosion test, indicating worsened corrosion resistance. These results are attributed to the predominant presence of Mn3+ and Mn2+ forms, rather than the Mn4+ form, which has a smaller basicity difference with SiO2, and due to the low melting point. The monoclinic phase fraction decreased as the doping amount of CeO2 increased in CeO2-doped CSZ, but the rate of decrease was lower compared to MnO2-doped CSZ. The monoclinic phase decreased as the doping amount increased, but the Vickers hardness and flexural strength showed a decreasing trend due to the low relative density. The destabilization behavior of Ca in SEM-EDS images before and after corrosion was difficult to identify due to the presence of Ca in the slag, and the destabilization behavior of Ce due to slag after corrosion was not observed. In the XRD data of the specimen surface after the corrosion test, the fraction of the monoclinic phase increased compared to before the test but showed a lower monoclinic phase fraction compared to CSZ. It is believed that CeO2 has superior corrosion resistance compared to CaO because Ce predominantly exists in the form of Ce4+, which has a smaller difference in basicity within the zirconia lattice. Full article
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23 pages, 15007 KiB  
Article
Effect of High Temperature and Thermal Cycle of 4043 Al Alloy Manufactured through Continuous Casting Direct Rolling
by Bo-Chin Huang and Fei-Yi Hung
Materials 2023, 16(22), 7176; https://doi.org/10.3390/ma16227176 - 15 Nov 2023
Cited by 1 | Viewed by 1043
Abstract
CCDR 4043 Al alloys are an outstanding candidate for producing mechanical components for automotive or aircraft engines. Two experimental environments—sustained high temperature and repeated heating–cooling—were simulated in the laboratory to replicate the actual operating conditions of engine components. This research investigated the microstructural [...] Read more.
CCDR 4043 Al alloys are an outstanding candidate for producing mechanical components for automotive or aircraft engines. Two experimental environments—sustained high temperature and repeated heating–cooling—were simulated in the laboratory to replicate the actual operating conditions of engine components. This research investigated the microstructural evolution, mechanical properties, and fracture characteristics of the 4043 Al alloy manufactured through the continuous casting direct rolling (CCDR) process under different post-processing conditions. The CCDR process combines continuous casting, billet heating, and subsequent continuous rolling in a single equipment of production line, enabling the mass production of Al alloy in a cost-effective and energy-efficient manner. In the present work, the 4043 alloy was subjected to two environmental conditions: a sustained high-temperature environment (control group) and a cyclic heating–cooling environment (experimental group). The maximum temperature was set to 200 °C in the experiment. The experimental results show that, in a sustained high temperature working environment, the strength and elongation of the CCDR 4043 Al alloy tend to be stable. The overall effect involves the Al matrix softening and the spheroidization of eutectic Si caused by prolonged exposure to high temperature. This can enhance its ductility while retaining a certain level of mechanical strength. Comparatively, in the working environment of cyclic heating–cooling (thermal cycle), the direction of Si diffusion was different in each cycle, thus leading to the formation of an irregular Ai–Si eutectic structure containing precipitated Si particles of different sizes. The two compositions of Al and Si with very different thermal expansion coefficients may induce defects at the sharp points of Si particles under repeated heating–cooling, thereby reducing the strength and ductility of the material. The results of this work can confirm that the fracture behavior of 4043 Al alloys is obviously controlled by the morphology of the precipitated eutectic Si. In addition, CCDR 4043 Al alloys are not suitable to be used in working environments with a thermal cycle. In practical applications, it is necessary to add traces of special elements or to employ other methods to achieve the purpose of spheroidizing the precipitated eutectic Si and Al–Fe–Si phases to avoid the deterioration of strength and ductility under cyclic heating. To date, no other literature has explored the changes in the microstructure and mechanical properties of CCDR 4043 Al alloys across various time scales under the aforementioned working environments. In summary, the findings provide valuable insights into the effect of thermal conditions on the properties and behavior of CCDR 4043 Al alloys, offering potential applications for it in various engineering fields, such as the automotive and aerospace industries. Full article
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17 pages, 4223 KiB  
Article
Impact of Mn Alloying on Phase Stabilities, Magnetic Properties and Electronic Structures in Fe
by Hao Yang, Jin-Han Yang, Ying Zhao, Han Ma, Yanzhong Tian, Minghui Cai, Shuai Tang, Yandong Liu, Xiang Zhao, Hai-Le Yan and Liang Zuo
Materials 2023, 16(20), 6679; https://doi.org/10.3390/ma16206679 - 13 Oct 2023
Cited by 1 | Viewed by 803
Abstract
Impacts of Mn alloying on lattice stabilities, magnetic properties, electronic structures of the bcc and fcc phases and the fcc→bcc phase transition in Fe16xMnx (x = 0, 1 and 2) alloys are studied by first-principles calculations. Results show [...] Read more.
Impacts of Mn alloying on lattice stabilities, magnetic properties, electronic structures of the bcc and fcc phases and the fcc→bcc phase transition in Fe16xMnx (x = 0, 1 and 2) alloys are studied by first-principles calculations. Results show that the doped Mn atom prefers ferromagnetic and antiferromagnetic interaction with the host Fe atoms in the bcc and fcc phases, respectively. In these two phases, the magnetic moment of Mn is smaller and larger than Fe, respectively. The local moment of Fe is decided by the Fe-Mn distance in the bcc phase, whereas in the fcc phase, it is determined by spatial orientation with Mn. In the different phases, Mn prefers different site occupations, which can be understood from the electronic density of states near Fermi energy, implying a possibility of element redistribution during phase transition. The driving force of phase transition decreases with Mn alloying. Both destabilized bcc phase and stabilized fcc phase contribute to the inhibited phase transition, but the latter plays a dominant role. Antiferromagnetism is recognized as the key reason for the enhanced stability of the fcc phase by Mn alloying. Full article
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10 pages, 4242 KiB  
Article
Prediction of Grain Size in a High Cobalt Nickel-Based Superalloy
by Jingzhe Wang, Siyu Zhang, Liang Jiang, Shesh Srivatsa and Zaiwang Huang
Materials 2023, 16(17), 5776; https://doi.org/10.3390/ma16175776 - 23 Aug 2023
Viewed by 922
Abstract
With the advancement in computational approaches and experimental, simulation, and modeling tools in recent decades, a trial-and-validation method is attracting more attention in the materials community. The development of powder metallurgy Ni-based superalloys is a vivid example that relies on simulation and experiments [...] Read more.
With the advancement in computational approaches and experimental, simulation, and modeling tools in recent decades, a trial-and-validation method is attracting more attention in the materials community. The development of powder metallurgy Ni-based superalloys is a vivid example that relies on simulation and experiments to produce desired microstructure and properties in a tightly controlled manner. In this research, we show an integrated approach to predicting the grain size of industrial forgings starting from lab-scale cylindrical compression by employing modeling and experimental validation. (a) Cylindrical compression tests to obtain accurate flow stress data and the hot working processing window; (b) double-cone tests of laboratory scale validation; (c) sub-scale forgings for further validation under production conditions; and (d) application and validation on full-scale industrial forgings. The procedure uses modeling and simulation to predict metal flow, strain, strain rate, temperature, and the resulting grain size as a function of thermo-mechanical processing conditions. The models are calibrated with experimental data until the accuracy of the modeling predictions is at an acceptable level, which is defined as the accuracy at which the results can be used to design and evaluate industrial forgings. Full article
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13 pages, 6202 KiB  
Article
Influences of Fe Content and Cold Drawing Strain on the Microstructure and Properties of Powder Metallurgy Cu-Fe Alloy Wire
by Xiaobo Yuan, Ping Zhang, Jianxiang Wang, Biaobiao Yang and Yunping Li
Materials 2023, 16(14), 5180; https://doi.org/10.3390/ma16145180 - 23 Jul 2023
Cited by 5 | Viewed by 1517
Abstract
To study the effects of Fe content and cold drawing strain on the microstructure and properties, Cu-Fe alloys were prepared via powder metallurgy and hot extrusion. Scanning electron microscopy was applied to observe the Fe phase, and the ultimate tensile strength was investigated [...] Read more.
To study the effects of Fe content and cold drawing strain on the microstructure and properties, Cu-Fe alloys were prepared via powder metallurgy and hot extrusion. Scanning electron microscopy was applied to observe the Fe phase, and the ultimate tensile strength was investigated using a universal material testing machine. Alloying with an Fe content below 10 wt.% formed a spherically dispersed Fe phase via the conventional nucleation and growth mechanism, whereas a higher Fe content formed a water-droplet-like Fe phase via the spinodal decomposition mechanism in the as-extruded Cu-Fe alloy. Further cold drawing induced the fiber structure of the Fe phase (fiber strengthening), which could not be destroyed by subsequent annealing. As the Fe content increased, the strength increased but the electrical conductivity decreased; as the cold drawing strain increased, both the strength and the electrical conductivity roughly increased, but the elongation roughly decreased. After thermal–mechanical processing, the electrical conductivity and strength of the Cu-40Fe alloy could reach 51% IACS and 1.14 GPa, respectively. This study can provide insight into the design of high-performance Cu-Fe alloys by tailoring the size and morphology of the Fe phase. Full article
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14 pages, 7656 KiB  
Article
Investigating the Influence of Mg Content Variations on Microstructures, Heat-Treatment, and Mechanical Properties of Al-Cu-Mg Alloys
by Abdul Wahid Shah, Seong-Ho Ha, Jabir Ali Siddique, Bong-Hwan Kim, Young-Ok Yoon, Hyun-Kyu Lim and Shae K. Kim
Materials 2023, 16(12), 4384; https://doi.org/10.3390/ma16124384 - 14 Jun 2023
Cited by 2 | Viewed by 1115
Abstract
The objective of this study was to examine the impact of varying magnesium levels in the α-Al + S + T region of the Al-Cu-Mg ternary phase diagram on the solidification process, microstructure development, tensile properties, and precipitation hardening of Al-Cu-Mg-Ti alloys. The [...] Read more.
The objective of this study was to examine the impact of varying magnesium levels in the α-Al + S + T region of the Al-Cu-Mg ternary phase diagram on the solidification process, microstructure development, tensile properties, and precipitation hardening of Al-Cu-Mg-Ti alloys. The outcomes indicate that alloys with 3% and 5% Mg solidified with the formation of binary eutectic α-Al-Al2CuMg (S) phases, whereas in the alloy with 7% Mg, the solidification process ended with the formation of eutectic α-Al-Mg32(Al, Cu)49 (T) phases. Additionally, a significant number of T precipitates were noticed inside the granular α-Al grains in all alloys. In the as-cast condition, the 5% Mg-added alloy showed the best combination of yield strength (153 MPa) and elongation (2.5%). Upon T6 heat treatment, both tensile strength and elongation increased. The 7% Mg-added alloy had the best results, with a yield strength of 193 MPa and an elongation of 3.4%. DSC analysis revealed that the increased tensile strength observed after the aging treatment was associated with the formation of solute clusters and S″/S′ phases. Full article
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15 pages, 5776 KiB  
Article
Microstructural Considerations of a Multi-Pass Rolled Ti-Nb-Ta-Zr Alloy
by Doina Răducanu, Anna Nocivin, Vasile Dănuț Cojocaru, Nicolae Șerban, Nicoleta Zărnescu-Ivan, Raluca Elena Irimescu and Bogdan Mihai Gălbinașu
Materials 2023, 16(8), 3208; https://doi.org/10.3390/ma16083208 - 19 Apr 2023
Cited by 1 | Viewed by 1242
Abstract
The microstructural characteristic evolution was investigated during thermomechanical processing of Ti-29Nb-9Ta-10Zr (wt %) alloy, which consisted of, in a first stage, in a Multi-Pass Rolling with increasing thickness reduction of 20%, 40%, 60%, 80%, and 90%; in step two, the multi-pass rolled sample [...] Read more.
The microstructural characteristic evolution was investigated during thermomechanical processing of Ti-29Nb-9Ta-10Zr (wt %) alloy, which consisted of, in a first stage, in a Multi-Pass Rolling with increasing thickness reduction of 20%, 40%, 60%, 80%, and 90%; in step two, the multi-pass rolled sample with the highest thickness reduction (90%) was subjected to a series of three variants of static short recrystallization and then to a final similar aging. The objective was to evaluate the microstructural features evolution during thermomechanical processing (phase’s nature, morphology, dimensions, and crystallographic characteristics) and to find the optimal heat treatment variant for refinement of the alloy granulation until ultrafine/nanometric level for a promising combination of mechanical properties. The microstructural features were investigated by X-ray diffraction and SEM techniques through which the presence of two phases was recorded: the β-Ti phase and the α″-Ti martensitic phase. The corresponding cell parameters, dimensions of the coherent crystallite and the micro-deformations at the crystalline network level for both recorded phases were determined. The majority β-Ti phase underwent a strong refinement during the Multi-Pass Rolling process until ultrafine/nano grain dimension (about 9.8 nm), with subsequent slow growing during recrystallization and aging treatments, hindered by the presence of sub-micron α″-Ti phase dispersed inside β-Ti grains. An analysis concerning the possible deformation mechanisms was performed. Full article
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13 pages, 5997 KiB  
Article
Microstructure Evolution and Mechanical Properties of Al–Cu–Mg Alloys with Si Addition
by Abdul Wahid Shah, Seong-Ho Ha, Jabir Ali Siddique, Bong-Hwan Kim, Young-Ok Yoon, Hyun-Kyu Lim and Shae K. Kim
Materials 2023, 16(7), 2783; https://doi.org/10.3390/ma16072783 - 30 Mar 2023
Cited by 3 | Viewed by 1430
Abstract
The aim of this study was to investigate the impact of the addition of a minor quantity of Si on the microstructure evolution, heat treatment response, and mechanical properties of the Al–4.5Cu–0.15Ti–3.0Mg alloy. The microstructure analysis of the base alloy revealed the presence [...] Read more.
The aim of this study was to investigate the impact of the addition of a minor quantity of Si on the microstructure evolution, heat treatment response, and mechanical properties of the Al–4.5Cu–0.15Ti–3.0Mg alloy. The microstructure analysis of the base alloy revealed the presence of α-Al grains, eutectic α-Al-Al2CuMg (S) phases, and Mg32(Al, Cu)49 (T) phases within the Al grains. In contrast, the Si-added alloy featured the eutectic α-Al-Mg2Si phases, eutectic α-Al-S-Mg2Si, and Ti-Si-based intermetallic compounds in addition to the aforementioned phases. The study found that the Si-added alloy had a greater quantity of T phase in comparison to the base alloy, which was attributed to the promotion of T phase precipitation facilitated by the inclusion of Si. Additionally, Si facilitated the formation of S phase during aging treatment, thereby accelerating the precipitation-hardening response of the Si-added alloy. The as-cast temper of the base alloy displayed a yield strength of roughly 153 MPa, which increased to 170 MPa in the Si-added alloy. As a result of the aging treatment, both alloys exhibited a notable increase in tensile strength, which was ascribed to the precipitation of S phases. In the T6 temper, the base alloy exhibited a yield strength of 270 MPa, while the Si-added alloy exhibited a significantly higher yield strength of 324 MPa. This novel Si-added alloy demonstrated superior tensile properties compared to many commercially available high-Mg-added Al–Cu–Mg alloys, making it a potential replacement for such alloys in various applications within the aerospace and automotive industries. Full article
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