The emergence of ferrous-medium entropy alloys (FeMEAs) with excellent tensile properties represents a potential direction for designing alloys based on metastable engineering. In this study, an FeMEA is successfully fabricated using laser powder bed fusion (LPBF), a metal additive manufacturing technology. Tensile tests are conducted on the LPBF-processed FeMEA at room temperature and cryogenic temperatures (77 K). At 77 K, the LPBF-processed FeMEA exhibits high yield strength and excellent ultimate tensile strength through active deformation-induced martensitic transformation. Furthermore, due to the low stability of the face-centered cubic (FCC) phase of the LPBF-processed FeMEA based on nano-scale solute heterogeneity, stress-induced martensitic transformation occurs, accompanied by the appearance of a yield point phenomenon during cryogenic tensile deformation. This study elucidates the origin of the yield point phenomenon and deformation behavior of the FeMEA at 77 K.

Recent advancements in electronic devices and wireless communication technologies, particularly the rise of 5G, have raised concerns about the escalating electromagnetic pollution and its potential adverse impacts on human health and electronics. As a result, the demand for effective electromagnetic interference (EMI) shielding materials has grown significantly. Traditional materials face limitations in providing optimal solutions owing to inadequacy and low performance due to small thickness. MXene-based composite materials have emerged as promising candidates in this context owing to their exceptional electrical properties, high conductivity, and superior EMI shielding efficiency across a broad frequency range. This review examines the recent developments and advantages of MXene-based composite materials in EMI shielding applications, emphasizing their potential to address the challenges posed by electromagnetic pollution and to foster advancements in modern electronics systems and vital technologies.

This study explores the profound impact of varying oxygen content on microstructural and mechanical properties in specimens HO and LO. The higher oxygen concentration in specimen HO is found to significantly influence alpha lath sizes, resulting in a size of 0.5-1 μm, contrasting with the 1-1.5 μm size observed in specimen LO. Pore fraction, governed by oxygen concentration, is high in specimen HO, registering a value of 0.11%, whereas specimen LO exhibits a lower pore fraction (0.02%). Varied pore types in each specimen further underscore the role of oxygen concentration in shaping microstructural morphology. Despite these microstructural variations, the average hardness remains consistent at ~370 HV. This study emphasizes the pivotal role of oxygen content in influencing microstructural features, contributing to a comprehensive understanding of the intricate interplay between elemental composition and material properties.

In this study, a graphite block is fabricated using artificial graphite processing byproduct and phenolic resin as raw materials. Mechanical and electrical property changes are confirmed due to the preforming method. After fabricating preforms at 50, 100, and 150 MPa, CIP molding at 150 MPa is followed by heat treatment to prepare a graphite block. 150UP-CIP shows a 12.9% reduction in porosity compared with the 150 MPa preform. As the porosity is decreased, the bulk density, flexural strength, and shore hardness are increased by 14.9%, 102.4%, and 13.7%, respectively; and the deviation of density and electrical resistivity are decreased by 51.9% and 34.1%, respectively. Therefore, as the preforming pressure increases, the porosity decreases, and the electrical and mechanical properties improve.

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• Effect of Microstructural Change under Pressure during Isostatic Pressing on Mechanical and Electrical Properties of Isotropic Carbon Blocks
  Tae-Sub Byun, Sang-Hye Lee, Suk-Hwan Kim, Jae-Seung Roh
  Materials.2024; 17(2): 387.     CrossRef
• Effect of Pressure and Holding Time during Compression Molding on Mechanical Properties and Microstructure of Coke-Pitch Carbon Blocks
  Sun-Ung Gwon, Sang-Hye Lee, U-Sang Youn, Jae-Seung Roh
  Applied Sciences.2024; 14(2): 772.     CrossRef

Although the Ti–6Al–4V alloy has been used in the aircraft industry owing to its excellent mechanical properties and low density, the low formability of the alloy hinders broadening its applications. Recently, laser-powder bed fusion (L-PBF) has become a novel process for overcoming the limitations of the alloy (i.e., low formability), owing to the high degree of design freedom for the geometry of products having outstanding performance used in hightech applications. In this study, to investigate the effect of bulk shape on the microstructure and mechanical properties of L-PBFed Ti-6Al-4V alloys, two types of samples are fabricated using L-PBF: thick and thin samples. The thick sample exhibits lower strength and higher ductility than the thin sample owing to the larger grain size and lower residual dislocation density of the thick sample because of the heat input during the L-PBF process.

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• Cryogenic Tensile Behavior of Ferrous Medium-entropy Alloy Additively Manufactured by Laser Powder Bed Fusion
  Seungyeon Lee, Kyung Tae Kim, Ji-Hun Yu, Hyoung Seop Kim, Jae Wung Bae, Jeong Min Park
  journal of Korean Powder Metallurgy Institute.2024; 31(1): 8.     CrossRef
• Microstructural Evolution and Mechanical Properties of Ti-6Al-4V Alloy through Selective Laser Melting: Comprehensive Study on the Effect of Hot Isostatic Pressing (HIP)
  Gargi Roy, Raj Narayan Hajra, Woo Hyeok Kim, Jongwon Lee, Sangwoo Kim, Jeoung Han Kim
  journal of Korean Powder Metallurgy Institute.2024; 31(1): 1.     CrossRef
• Data-driven Approach to Explore the Contribution of Process Parameters for Laser Powder Bed Fusion of a Ti-6Al-4V Alloy
  Jeong Min Park, Jaimyun Jung, Seungyeon Lee, Haeum Park, Yeon Woo Kim, Ji-Hun Yu
  journal of Korean Powder Metallurgy Institute.2024; 31(2): 137.     CrossRef
• High-speed manufacturing-driven strength-ductility improvement of H13 tool steel fabricated by selective laser melting
  Yeon Woo Kim, Haeum Park, Young Seong Eom, Dong Gill Ahn, Kyung Tae Kim, Ji-hun Yu, Yoon Suk Choi, Jeong Min Park
  Powder Metallurgy.2023; 66(5): 582.     CrossRef

The CoCrFeMnNi high-entropy alloy (HEA), which is the most widely known HEA with a single facecentered cubic structure, has attracted significant academic attention over the past decade owing to its outstanding multifunctional performance. Recent studies have suggested that CoCrFeMnNi-type HEAs exhibit excellent printability for selective laser melting (SLM) under a wide range of process conditions. Moreover, it has been suggested that SLM can not only provide great topological freedom of design but also exhibit excellent mechanical properties by overcoming the strength–ductility trade-off via producing a hierarchical heterogeneous microstructure. In this regard, the SLM-processed CoCrFeMnNi HEA has been extensively studied to comprehensively understand the mechanisms of microstructural evolution and resulting changes in mechanical properties. In this review, recent studies on CoCrFeMnNi-type HEAs produced using SLM are discussed with respect to process-induced microstructural evolution and the relationship between hierarchical heterogeneous microstructure and mechanical properties.

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• Investigation of effects of process parameters on microstructure and fracture toughness of SLM CoCrFeMnNi
  Joseph Agyapong, Diego Mateos, Aleksander Czekanski, Solomon Boakye-Yiadom
  Journal of Alloys and Compounds.2024; 987: 173998.     CrossRef
• Cryogenic Tensile Behavior of Ferrous Medium-entropy Alloy Additively Manufactured by Laser Powder Bed Fusion
  Seungyeon Lee, Kyung Tae Kim, Ji-Hun Yu, Hyoung Seop Kim, Jae Wung Bae, Jeong Min Park
  journal of Korean Powder Metallurgy Institute.2024; 31(1): 8.     CrossRef
• Data-driven Approach to Explore the Contribution of Process Parameters for Laser Powder Bed Fusion of a Ti-6Al-4V Alloy
  Jeong Min Park, Jaimyun Jung, Seungyeon Lee, Haeum Park, Yeon Woo Kim, Ji-Hun Yu
  journal of Korean Powder Metallurgy Institute.2024; 31(2): 137.     CrossRef
• High-speed manufacturing-driven strength-ductility improvement of H13 tool steel fabricated by selective laser melting
  Yeon Woo Kim, Haeum Park, Young Seong Eom, Dong Gill Ahn, Kyung Tae Kim, Ji-hun Yu, Yoon Suk Choi, Jeong Min Park
  Powder Metallurgy.2023; 66(5): 582.     CrossRef

High-entropy alloys (HEAs) are attracting attention because of their excellent properties and functions; however, they are relatively expensive compared with commercial alloys. Therefore, various efforts have been made to reduce the cost of raw materials. In this study, MIM is attempted using coarse equiatomic CoCrFeMnNi HEA powders. The mixing ratio (powder:binder) for HEA feedstock preparation is explored using torque rheometer. The block-shaped green parts are fabricated through a metal injection molding process using feedstock. The thermal debinding conditions are explored by thermogravimetric analysis, and solvent and thermal debinding are performed. It is densified under various sintering conditions considering the melting point of the HEA. The final product, which contains a small amount of non-FCC phase, is manufactured at a sintering temperature of 1250°C.

The Ti-6Al-4V lattice structure is widely used in the aerospace industry owing to its high specific strength, specific stiffness, and energy absorption. The quality, performance, and surface roughness of the additively manufactured parts are significantly dependent on various process parameters. Therefore, it is important to study process parameter optimization for relative density and surface roughness control. Here, the part density and surface roughness are examined according to the hatching space, laser power, and scan rotation during laser-powder bed fusion (LPBF), and the optimal process parameters for LPBF are investigated. It has high density and low surface roughness in the specific process parameter ranges of hatching space (0.06–0.12 mm), laser power (225–325 W), and scan rotation (15°). In addition, to investigate the compressive behavior of the lattice structure, a finite element analysis is performed based on the homogenization method. Finite element analysis using the homogenization method indicates that the number of elements decreases from 437,710 to 27 and the analysis time decreases from 3,360 to 9 s. In addition, to verify the reliability of this method, stress–strain data from the compression test and analysis are compared.

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• Enhanced Microstructure and Wear Resistance of Ti–6Al–4V Alloy with Vanadium Carbide Coating via Directed Energy Deposition
  Ui Jun Ko, Ju Hyeong Jung, Jung Hyun Kang, Kyunsuk Choi, Jeoung Han Kim
  Materials.2024; 17(3): 733.     CrossRef
• Microstructural Evolution and Mechanical Properties of Ti-6Al-4V Alloy through Selective Laser Melting: Comprehensive Study on the Effect of Hot Isostatic Pressing (HIP)
  Gargi Roy, Raj Narayan Hajra, Woo Hyeok Kim, Jongwon Lee, Sangwoo Kim, Jeoung Han Kim
  journal of Korean Powder Metallurgy Institute.2024; 31(1): 1.     CrossRef