Article
Nanoscience & Nanotechnology
J. J. Shi, S. A. Zhou, H. H. Chen, G. H. Cao, A. M. Russell, Z. J. Zhou, X. B. Qi, C. P. Li, G. F. Chen
Summary: The study found that in SLMed Inconel 718 alloy, the grain size remained stable during creep, with vertical samples having a longer creep rupture life, while stress concentration at transverse grain boundaries led to intergranular fracture failure in both building orientational samples. The anisotropy of creep behavior could not be eliminated by the present heat treatment schedule.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Engineering, Manufacturing
Young-Kyun Kim, Min-Seok Baek, Sangsun Yang, Kee-Ahn Lee
Summary: The study investigates the high-cycle fatigue properties and deformation behavior of additively manufactured equiatomic CoCrFeMnNi high-entropy alloys (HEAs), revealing their superior yield strength and high fatigue resistance. The excellent fatigue resistance of the SLM-built HEA is attributed to its unique microstructural characteristics, internal defects, and deformation twins generated during cyclic load. The un-melted powder generated during the additive manufacturing process also contributes to the HCF resistance of the SLM-built HEA.
ADDITIVE MANUFACTURING
(2021)
Article
Nanoscience & Nanotechnology
Binghua Lv, Fengtao Wang, Xiaodong Niu, Lujie Zhang, Xinhua Wu, Youbin Lai, Bo Hong, Sheng Cao
Summary: In this study, a novel in-situ formed graded microstructure in SLM stainless steel was reported, and the relationship between processing, microstructure and properties was systematically investigated. The findings showed that the volume fractions of austenite and oxide decreased with the build height, and these variations affected the mechanical properties.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Yacheng Fang, Pan Ma, Shuimiao Wei, Zhiyu Zhang, Dongye Yang, Hong Yang, Shiguang Wan, Konda Gokuldoss Prashanth, Yandong Jia
Summary: The trade-off between strength and ductility in alloys has been a persistent issue in engineering applications. Conventional techniques often sacrifice ductility to increase strength, while high entropy alloys with dual-phase structures exhibit excellent strength-ductility synergy.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Multidisciplinary
Biliang Yuan, Chuanqiang Li, Yong Dong, Yang Yang, Peng Zhang, Zhengrong Zhang
Summary: The as-printed Al0.3CoCrFeNiCu high-entropy alloy (HEA) was successfully fabricated using selective laser melting (SLM) technology. The SLM-processed HEA exhibited a simple disordered face centered cubic solid solution with excellent mechanical properties. However, the presence of defects in the SLM alloy limits its application.
MATERIALS & DESIGN
(2022)
Article
Nanoscience & Nanotechnology
H. Q. Li, F. L. Shen, H. Guo, R. Zong, X. Y. Fang, L. J. Zhang
Summary: This study explores a novel laser scanning strategy to achieve distinct dense microstructures in alloys through melting scanning and non-melting scanning, resulting in refined grains and the production of ε-martensite, which can effectively tune the mechanical properties.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
Pengfei Gu, Tengbo Qi, Lan Chen, Tong Ge, Xudong Ren
Summary: Refractory high entropy alloys (RHEAs) have excellent heat tolerance and mechanical properties, making them a promising direction for high-temperature structural materials. In this study, bulk VNbMoTaW RHEA was fabricated using selective laser melting (SLM), and the impact of laser scanning speed on its surface morphology, internal defect, microstructure, and mechanical properties was investigated. The results showed that pores and cracks were the main defects in the SLMed VNbMoTaW RHEA, with lower scanning speeds reducing the presence of pores but the manifestation of cracks remaining inevitable. The microstructure revealed the existence of a columnar dendritic structure and a cellular structure on the top surface, while the average microhardness and compressive strength of the SLMed VNbMoTaW RHEA were higher than those processed by arc-melting.
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
J. J. Shi, Z. Q. Zhou, K. Xu, G. Y. Zhou, Z. J. Zhou, C. P. Li, G. F. Chen, X. G. Lu, G. H. Cao
Summary: This study investigates the effect of heat treatment on the microstructure and small punch creep property of Inconel 718 alloy fabricated by selective laser melting (SLM). The results show that a higher temperature solution treatment can eliminate stress concentration and lead to grain transformation and recrystallization. The distribution of grain boundaries and twin boundaries affects the creep life and fracture mode.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Xiquan Jia, Zhenlin Xu, Yizhu He, Shengxuan Zhou, Xiaojie Du, Hui Zhang, Aiqin Mao
Summary: This study investigates the microstructure and oxidation behavior of the CoCrFeMnNi high-entropy alloy (HEA) prepared by selective laser melting (SLM). Annealing after the SLM process significantly improves the alloy's structure and oxidation resistance. Therefore, subsequent heat treatment plays a crucial role in enhancing the performance of the alloy.
METALS AND MATERIALS INTERNATIONAL
(2023)
Article
Chemistry, Physical
Yiyu Huang, Zhonghao Xie, Wenshu Li, Haoyu Chen, Bin Liu, Bingfeng Wang
Summary: In this study, dynamic impact experiments were conducted to investigate the dynamic mechanical properties of SLM-NiCrFeCoMo0.2 high entropy alloy (HEA) with different molten pool sizes. The results showed that SLM-NiCrFeCoMo0.2 HEA exhibited high impact energy absorption density and compressive strength at high strain rates. The relationship between molten pool structure and precipitation distribution was studied to understand the contribution of precipitation strengthening to the material's strength.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Jingbo Gao, Yuting Jin, Yongqiang Fan, Dake Xu, Lei Meng, Cong Wang, Yuanping Yu, Deliang Zhang, Fuhui Wang
Summary: In this study, a broad-spectrum antibacterial high-entropy alloy (HEA) was successfully fabricated using selective laser melting (SLM) and in-situ alloying. The SLM-fabricated HEA showed enhanced antibacterial ability compared to the conventionally fabricated HEA, making it suitable for potential applications requiring antibacterial properties.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Chemistry, Physical
Enrico Gianfranco Campari, Angelo Casagrande
Summary: The equiatomic high entropy alloy (HEA) of CrNiFeCoMn composition exhibits different microstructures and mechanical properties under different temperature conditions. At low and intermediate temperatures, the alloy behaves as a supersaturated solid solution with the presence of nitrides and σ nanostructures. However, at high temperatures, the alloy transforms into a single crystal structure with the disappearance of nitride and σ phase precipitates.
Article
Chemistry, Physical
Young-Kyun Kim, Ji-Eun Ahn, Yongwook Song, Hyunjoo Choi, Sangsun Yang, Kee-Ahn Lee
Summary: The Y2O3-reinforced equiatomic CrMnFeCoNi high-entropy alloy (HEA) matrix nanocomposite, fabricated through high-energy attrition milling and selective laser melting (SLM) additive manufacturing, exhibited superior mechanical properties with higher nanohardness compared to similar HEAs produced by casting and SLM. This suggests that dispersion hardening by Y2O3 nanoparticles can effectively improve the mechanical properties of SLM-built CrMnFeCoNi HEA matrix nanocomposites.
Article
Materials Science, Multidisciplinary
Xu-Han Gu, Tao Lu, Tao Zhang, Wei Guo, Ye Pan, Ting Dai
Summary: The anisotropy of microstructures and mechanical properties of FeCoNiCr0.5 high-entropy alloys prepared by selective laser melting was investigated. It was found that the alloy exhibited different microstructures and mechanical properties in different directions, leading to anisotropic behavior.
Article
Nanoscience & Nanotechnology
Minghong Li, Lilin Wang, Haiou Yang, Shuya Zhang, Xin Lin, Weidong Huang
Summary: Selective laser melting (SLM) has unique advantages in manufacturing oxide dispersion strengthened alloys. This study comparatively investigates the microstructure and mechanical properties of Inconel 625 alloy and Y2O3 strengthened Inconel 625 alloy prepared by SLM. The results show that the Y2O3/Inconel 625 specimen has better density, grain structure, and mechanical properties.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Gi-Su Ham, Young-Kyun Kim, Young Sang Na, Kee-Ahn Lee
Summary: The study found that the addition of Ti significantly improved the high-temperature oxidation resistance of AlCoCrFeNi high-entropy alloy, with Ti1.0 alloy showing superior performance at 1100 degrees Celsius compared to other major alloys. Observation after oxidation tests revealed that Ti1.0 alloy had localized Al2O3 spallation, accelerated BCC -> FCC phase transformation, and formation of an FCC phase layer with decreased thickness.
METALS AND MATERIALS INTERNATIONAL
(2021)
Article
Materials Science, Multidisciplinary
Young-Kyun Kim, Kyu-Sik Kim, Young-Beum Song, Jung Hyo Park, Kee-Ahn Lee
Summary: This study investigated the effect of multi-step heat treatment on the microstructure, mechanical properties, and fracture behavior of thick 15Co-12Ni secondary hardening steel. The heat-treated sample showed superior tensile strength and elongation, with the presence of nano-sized carbides positively affecting both strength and ductility. The findings also indicated good fracture toughness and ductile fracture mode, along with the correlation among microstructural evolution, deformation, and fracture mechanisms.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Ji-Eun Ahn, Young-Kyun Kim, Sang-Hoon Yoon, Kee-Ahn Lee
Summary: An equiatomic CoCrFeMnNi high entropy alloy (HEA) coating layer was successfully prepared via a cold spray process, with heat treatments employed to control its microstructure and nano-indentation properties. Fine Cr-rich precipitates were found at grain boundaries and particle boundaries after heat treatment, and deformation twins were observed to significantly affect hardness improvement.
METALS AND MATERIALS INTERNATIONAL
(2021)
Article
Engineering, Multidisciplinary
Young-Kyun Kim, Ji-Hun Yu, Hyoung Seop Kim, Kee-Ahn Lee
Summary: The study investigated the effect of carbon content on the microstructure evolution, tensile properties, and deformation mechanisms of high-entropy alloy matrix nanocomposites additively manufactured by selective laser melting. It was found that an increase in carbon content led to enhancements in strength, work hardening rate, and elongation, while also affecting the microstructural features such as nano-sized carbides and average grain sizes. Furthermore, the formation of dislocation networks and deformation twins were observed, contributing to the high back stresses and yield strengths of the samples.
COMPOSITES PART B-ENGINEERING
(2021)
Article
Materials Science, Multidisciplinary
Kyu-Sik Kim, Young-Kyun Kim, Hyeon-Jin Kim, Jeoung Han Kim, Kee-Ahn Lee
Summary: The severe plastic deformation through warm caliber-rolling significantly improved the mechanical properties of hypereutectoid steels, especially the yield strength and tensile strength. Moreover, the fatigue limit and fracture elongation were also enhanced, indicating that the 81% reduction in area sample exhibited superior comprehensive performance.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Engineering, Manufacturing
Young-Kyun Kim, Min-Seok Baek, Sangsun Yang, Kee-Ahn Lee
Summary: The study investigates the high-cycle fatigue properties and deformation behavior of additively manufactured equiatomic CoCrFeMnNi high-entropy alloys (HEAs), revealing their superior yield strength and high fatigue resistance. The excellent fatigue resistance of the SLM-built HEA is attributed to its unique microstructural characteristics, internal defects, and deformation twins generated during cyclic load. The un-melted powder generated during the additive manufacturing process also contributes to the HCF resistance of the SLM-built HEA.
ADDITIVE MANUFACTURING
(2021)
Article
Materials Science, Multidisciplinary
Jung-Uk Lee, Young-Kyun Kim, Seong-Soo Kim, Kee-Ahn Lee
Summary: This study investigates the effects of heat treatment (DA and STA) on the microstructure and mechanical properties of an Ni-Co-based superalloy manufactured using selective laser melting (SLM). The results show that the mechanical properties of the alloy are improved by changing the dislocation density and the fraction of carbide and gamma ' phase through heat treatment.
ADVANCED ENGINEERING MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Young-Kyun Kim, Kee-Ahn Lee
Summary: The study on fabricating ultra-strong pure copper using cold spray technology showed that different carrier gas species significantly influence the microstructural characteristics, mechanical properties, and deformation mechanisms. N2 and He carrier gases can achieve high yield strengths, but there are differences in the deformation microstructures and mechanisms between the two.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Young-Kyun Kim, Min-Jong Kim, Yu-Jin Hwang, Shae K. Kim, Hyun-Kyu Lim, Kee-Ahn Lee
Summary: The study investigated the effect of tailored microstructures in 0.5 wt% CaO added AZ31 on tensile, high-cycle fatigue, and fatigue crack growth properties. The findings revealed that adding CaO resulted in a significant reduction in average grain size, improved distribution and higher fraction of fine-precipitates. Improved tensile properties, increased high-cycle fatigue limit, and inhibition of fatigue crack source formation were observed in CaO-AZ31 compared to conventional AZ31.
KOREAN JOURNAL OF METALS AND MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Young-Kyun Kim, Kee-Ahn Lee
Summary: Direct energy deposition (DED) was used to additively manufacture 22-13-5 austenitic stainless steel (SS), which exhibited excellent mechanical properties and corrosion resistance. In-situ formed oxide-driven strengthening was utilized in this study. The DED-processed austenitic SS matrix nanocomposite (SSMNC) showed unique microstructural features and nano-sized precipitates, leading to high yield strength and ductility.
MATERIALS CHARACTERIZATION
(2021)
Article
Chemistry, Physical
Young-Kyun Kim, Ji-Eun Ahn, Yongwook Song, Hyunjoo Choi, Sangsun Yang, Kee-Ahn Lee
Summary: The Y2O3-reinforced equiatomic CrMnFeCoNi high-entropy alloy (HEA) matrix nanocomposite, fabricated through high-energy attrition milling and selective laser melting (SLM) additive manufacturing, exhibited superior mechanical properties with higher nanohardness compared to similar HEAs produced by casting and SLM. This suggests that dispersion hardening by Y2O3 nanoparticles can effectively improve the mechanical properties of SLM-built CrMnFeCoNi HEA matrix nanocomposites.
Article
Materials Science, Multidisciplinary
Young-Kyun Kim, Min-Chul Kim, Kee-Ahn Lee
Summary: The study introduced a new method for developing high-performance CrMnFeCoNi HEAs at cryogenic temperatures by utilizing additive manufacturing and the addition of interstitial atoms. The HEA nanocomposite fabricated using laser powder bed fusion exhibited superior mechanical properties, with excellent yield strengths, tensile strengths, and Charpy impact energies at both room temperature and cryogenic temperature.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Kyu-Sik Kim, Young-Kyun Kim, Sangsun Yang, Bonuk Koo, Kee-Ahn Lee
Summary: This study demonstrates that LPBF-built carbon-bearing high Co-Ni steels exhibit varying mechanical properties at different laser scan rates, with a relative density of up to 99.9% and excellent strength and ductility. As the laser scan rate increases, the proportions and sizes of Mo-rich carbides also increase, leading to higher compressive yield strengths in the LPBF-manufactured steels.
Article
Nanoscience & Nanotechnology
Jung-Uk Lee, Young-Kyun Kim, Seong-Moon Seo, Kee-Ahn Lee
Summary: This study demonstrates that the CM247LC alloy manufactured using the L-PBF and SLM methods has excellent mechanical properties. The microstructure and mechanical properties of the SLM-built CM247LC alloy can be improved through HIP post treatment. The study also reveals that the defect characteristics of the alloy vary significantly with different scan speeds and hatch spaces, with the optimal microstructure achieved at an intermediate scan speed.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Young-Kyun Kim, Kee-Ahn Lee
Summary: This study investigated a strategy to enhance the strength of selective laser melted carbon-containing high-entropy alloys through microstructure control. After aging treatment, the tensile strength and deformation mechanism of the alloys changed significantly, showing higher strain hardening capacity.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Engineering, Manufacturing
Przemyslaw Golebiewski, Pawel Wienclaw, Jaroslaw Cimek, Pawel Socha, Dariusz Pysz, Adam Filipkowski, Grzegorz Stepniewski, Olga Czerwinska, Ireneusz Kujawa, Ryszard Stepien, Rafal Kasztelanic, Andrzej Burgs, Ryszard Buczynski
Summary: We report the development of a 3D printing process for producing soft glass optical fibers. The process involves direct printing using a miniaturized crucible and depositing straight horizontally-oriented lines to replace traditional assembly techniques. Experimental results demonstrate good performance of the printed photonic crystal fiber preform.
ADDITIVE MANUFACTURING
(2024)