Article
Crystallography
Ozkan Gokcekaya, Takuya Ishimoto, Tsubasa Todo, Ryoya Suganuma, Ryo Fukushima, Takayuki Narushima, Takayoshi Nakano
Summary: This study focuses on improving the quality of as-built pure Cr components to industrial level through controlling the scan length during laser powder bed fusion processing. Short scan length can enhance the density, strengthen the texture, and improve the mechanical properties of the as-built pure Cr.
Article
Optics
Wenpeng Shao, Bei He, Changyue Qiu, Zhuo Li
Summary: This study investigates the effects of hatch spacing and laser remelting on the microstructure and growth texture of IN718 superalloy fabricated using laser powder bed fusion. The study finds that increasing hatch spacing influences the growth texture and dendrite morphology, while laser remelting selects preferentially oriented grains and improves heat input.
OPTICS AND LASER TECHNOLOGY
(2022)
Article
Engineering, Manufacturing
Keyvan Safaei, Mohammadreza Nematollahi, Parisa Bayati, Fatemeh Kordizadeh, Mohsen Taheri Andani, Hossein Abedi, Behrang Poorganji, Mohammad Elahinia
Summary: There is a growing interest in additive manufacturing (AM) techniques for producing complex-shaped parts and tailoring the microstructure and properties. NiTi-based shape memory alloys (SMA) have a poor machinability and require additional treatments. The build orientation approach is used to control the crystallographic texture of LPBF-processed NiTi specimens. The study shows the significant effect of building orientation on the crystallographic texture and discusses the mechanism of this approach. The thermomechanical properties of the printed samples are assessed and correlated to the crystallographic textures.
ADDITIVE MANUFACTURING
(2022)
Article
Materials Science, Multidisciplinary
Liming Yao, Zhongmin Xiao, Zhiongsheng Hoo, Chao Tang, Jing Qiao, Yanmei Zhang
Summary: A multi-physics simulation model has been established to investigate the influence of Laser powder bed fusion parameters on the spatial composition distribution and grain growth mechanism of the single-track printed dissimilar alloys. Our study shows that alloy composition gradient isosurfaces can be used to visualize the spatial distribution of alloy composition for miscible dissimilar alloys. When the melt pool aspect ratio changes from large to small, the grain growth transitions from the temperature gradient mode to composition gradient mode and then to the mixed mode.
MATERIALS RESEARCH LETTERS
(2023)
Article
Engineering, Manufacturing
Shi-Hai Sun, Koji Hagihara, Takuya Ishimoto, Ryoya Suganuma, Yun-Fei Xue, Takayoshi Nakano
Summary: This study examines the variations in microstructure, crystallographic texture, and mechanical properties of specimens fabricated by different powder bed fusion technologies for a model material. While both EB-PBF and L-PBF can achieve cubic crystallographic textures, their formation mechanisms differ. L-PBF-built specimens exhibit better ductility but slightly lower strength compared to EB-PBF-built specimens under similar conditions.
ADDITIVE MANUFACTURING
(2021)
Article
Engineering, Manufacturing
Takuya Ishimoto, Koji Hagihara, Kenta Hisamoto, Takayoshi Nakano
Summary: Crystallographic orientation control in metal additive manufacturing is crucial for tailoring the functions of metallic parts. The stability of crystallographic texture is not widely discussed despite its importance in fabricating texture-controlled functional parts. Investigations were conducted on crystallographic texture stability under laser powder bed fusion using two methodologies.
ADDITIVE MANUFACTURING
(2021)
Article
Nanoscience & Nanotechnology
Yunhao Zhao, Fan Meng, Chuan Liu, Susheng Tan, Wei Xiong
Summary: It has been found that conducting a higher temperature homogenization process on Inconel 718 alloys can effectively remove residual stress and introduce isotropic microstructures and tensile properties, crucial for engineering applications. This method also improves the isotropic precipitation of strengthening phases during subsequent aging processes, aiding in the development of effective post-heat treatments for additively manufactured alloys.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Review
Materials Science, Multidisciplinary
Prince Valentine Cobbinah, Sae Matsunaga, Yoko Yamabe-Mitarai
Summary: This review presents the research progress in the laser powder bed fusion (LPBF) process and the control of crystallographic texture, as well as the influence of process parameters on texture and microstructural evolution, and the effects on properties.
ADVANCED ENGINEERING MATERIALS
(2023)
Review
Engineering, Manufacturing
Zhen Xiao, Wenhui Yu, Hongxun Fu, Yaoji Deng, Yongling Wu, Hongyu Zheng
Summary: This review provides an in-depth insight into laser powder bed fusion (LPBF) technology and its applications with aluminium alloys. It discusses the influence of thermal dynamics on microstructure in LPBF and summarizes the methods to refine microstructures in LPBF fabrication of various aluminium alloys. The review concludes with a summary of microstructural control and an outlook on the challenges and potential research topics in LPBF with Al alloys.
VIRTUAL AND PHYSICAL PROTOTYPING
(2023)
Article
Materials Science, Multidisciplinary
Ning Li, Ting Wang, Liang Zhang, Lixia Zhang
Summary: This study investigates the crack morphology and crystallographic orientation of a specific alloy in additive manufacturing, demonstrating the mechanisms of crack initiation and propagation. The findings highlight that solidification cracks are the most common, with the wide temperature range and grain boundaries being the main factors of cracking susceptibility. Additionally, the LPBF process has an influence on crack initiation and propagation.
MATERIALS CHARACTERIZATION
(2023)
Article
Materials Science, Coatings & Films
Hao Luo, Xiaoqiang Li, Cunliang Pan, Pengjiang He, Keli Zeng, Ke Hu, Huiyun Li, Chao Yang
Summary: This study investigated the microstructure and isothermal oxidation properties of CoNiCrAlY coating prepared by LPBF at 1100 degrees C. The coating exhibited dense, uniform, and crack-free characteristics, with a low thermal growth oxide layer growth rate during isothermal oxidation, forming Cr2O3 oxides initially and α-Al2O3 scale as well as mixed oxides on the surface with prolonged oxidation time.
SURFACE & COATINGS TECHNOLOGY
(2021)
Article
Chemistry, Multidisciplinary
Tejas Ramakrishnan, Amit Kumar, Tumulu S. Kumar, Sunyong Kwon, Jose A. Muniz-Lerma, Raynald Gauvin, Mathieu Brochu
Summary: Additive manufacturing of tungsten (W) is challenging due to its high melting point and brittleness from GB oxides. In this study, W processing through laser powder bed fusion was investigated. Parts were fabricated under argon (Ar) and nitrogen (N2) atmospheres, with crack-free samples produced under N2 atmosphere revealing increased hardness compared to samples produced under Ar atmosphere with cracks and oxide precipitates at grain boundaries. The presence of nitrogen in the samples resulted in hindrance to oxygen diffusion, reducing oxide levels at grain boundaries.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Rafael de Moura Nobre, Willy Ank de Morais, Matheus Tavares Vasques, Jhoan Guzman, Daniel Luiz Rodrigues Junior, Henrique Rodrigues Oliveira, Railson Bolsoni Falcao, Fernando Jose Gomes Landgraf
Summary: This study investigates the influence of laser power and scanning speed on microstructure and crystallographic texture formation of Nb-48Ti alloy fabricated using laser powder bed fusion process. Higher values of power and scanning speed favor an increase of near-cube-on-face texture and a reduction in Young's modulus.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Engineering, Manufacturing
I Ferretto, D. Kim, N. M. Della Ventura, M. Shahverdi, W. Lee, C. Leinenbach
Summary: The iron-based Fe-17Mn-5Si-10Cr-4Ni shape memory alloy (SMA) manufactured by laser powder bed fusion (LPBF) exhibits high strength, elongation, and ductility after annealing, as well as pronounced shape memory effect (SME) and pseudo-elasticity (PE) exceeding those of conventionally fabricated alloys. The texture generated during the LPBF process significantly influences SME and PE, with improved strain recovery observed when the loading direction is parallel to the build direction.
ADDITIVE MANUFACTURING
(2021)
Article
Materials Science, Multidisciplinary
Xiaojun Shen, Fanbo Meng, Kwang Boon Lau, Pei Wang, Christopher H. T. Lee
Summary: In this study, a strong lambda-fiber texture was achieved in Fe-3.5wt%Si electrical steel using the LPBF process. The formation of amorphous precipitates in additively manufactured Fe-Si alloy was also reported for the first time.
MATERIALS CHARACTERIZATION
(2022)
Article
Materials Science, Multidisciplinary
Jiawei Yang, Qiang Li, Junjie Li, Jinshuai Yang, Ran Zhang, Mitsuo Niinomi, Takayoshi Nakano
Summary: Cu-doped hydroxyapatite/TiO2 composite coatings were prepared using an electrochemical method, resulting in improved adhesion and antibacterial properties. These coatings showed high biocompatibility and promoted cell proliferation.
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
(2023)
Article
Nanoscience & Nanotechnology
Shunsei Takeda, Kosuke Ueki, Kyosuke Ueda, Masaaki Nakai, Takayoshi Nakano, Takayuki Narushima
Summary: This study investigates the microstructure and mechanical properties changes of the Co-20Cr-15W-10Ni alloy tube, which is used as a balloon-expandable stent after heat treatment. It is the first report on improving mechanical properties through microstructure control in CCWN alloy tubes. Optimized heat treatment conditions are proposed for the development of small-diameter stents. The strength and plastic elongation of the alloy tube increased with decreasing grain size.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Tomoki Kuroda, Haruki Masuyama, Yoshiaki Toda, Tetsuya Matsunaga, Tsutomu Ito, Makoto Watanabe, Ryosuke Ozasa, Takuya Ishimoto, Takayoshi Nakano, Masayuki Shimojo, Yoko Yamabe-Mitarai
Summary: Ti-6Al-4Nb-4Zr alloy was prepared by SLM and its microstructure evolution during SLM and heat treatments was investigated. The unique microstructure induced by SLM affected the high-temperature compressive strength and creep properties of the samples. The cooling rate determined the martensite size and grain size, which in turn influenced the compressive strength. Grain boundary sliding was the dominant creep deformation mechanism, and creep life depended on the grain size. HIP treatment improved the creep life by eliminating pores introduced by SLM.
MATERIALS TRANSACTIONS
(2023)
Article
Materials Science, Multidisciplinary
Ken Cho, Naohide Morita, Hiromasa Matsuoka, Hiroyuki Y. Yasuda, Mitsuharu Todai, Minoru Ueda, Masao Takeyama, Takayoshi Nakano
Summary: In this study, the microstructure and tensile properties of Ti-48Al-2Cr-2Nb (at%) rods fabricated by EB-PBF were investigated by changing the input energy density. It was found that a unique layered microstructure consisting of an equiaxed y grain layer and a duplex region can be formed within a certain range of energy density. The morphological changes in the layered microstructure were attributed to the variation of temperature distribution caused by increasing energy density. Furthermore, it was observed that the strength of the alloys can be improved by decreasing the width of the y band and increasing the a2/y lamellar grain in the duplex region, while the ductility of the alloys can be enhanced by increasing the width of the y band and the fraction of the equiaxed y grain in the duplex region.
MATERIALS TRANSACTIONS
(2023)
Article
Materials Science, Multidisciplinary
Soung Yeoul Ahn, Sang Guk Jeong, Eun Seong Kim, Suk Hoon Kang, Jungho Choe, Joo Young Ryu, Dae Woon Choi, Jin Seok Lee, Jung-Wook Cho, Takayoshi Nakano, Hyoung Seop Kim
Summary: Interest in recycling Zircaloy-4 scrap has grown recently due to its high melting temperature and powder reactivity challenges for metal additive manufacturing (MAM). This study successfully built Zircaloy-4 parts using laser powder bed fusion MAM for the first time while suppressing powder reactivity. The mechanical properties of the printed Zircaloy-4 were evaluated at room temperature and reactor operating temperature, showing remarkable yield strengths at both temperatures. This study serves as a starting point for safe Zircaloy-4 additive manufacturing.
METALS AND MATERIALS INTERNATIONAL
(2023)
Article
Clinical Neurology
Aira Matsugaki, Manabu Ito, Yoshiya Kobayashi, Tadaaki Matsuzaka, Ryosuke Ozasa, Takuya Ishimoto, Hiroyuki Takahashi, Ryota Watanabe, Takayuki Inoue, Katsuhiko Yokota, Yoshio Nakashima, Takashi Kaito, Seiji Okada, Takao Hanawa, Yukihiro Matsuyama, Morio Matsumoto, Hiroshi Taneichi, Takayoshi Nakano
Summary: Although autologous bone grafting is considered as an ideal source for interbody fusion, the influence of intervertebral devices should not be overlooked. Artificial spinal devices need to join the vertebrae together and rapidly recover the original function of the spine. Ordered mineralization of apatite crystals on collagen accelerates bone functionalization, and the ingrowth of an ordered collagen and apatite matrix is crucial for stable spinal function.
Article
Chemistry, Physical
Kazuhisa Sato, Shunya Takagi, Satoshi Ichikawa, Takuya Ishimoto, Takayoshi Nakano
Summary: Using transmission electron microscopy and energy-dispersive x-ray spectroscopy, we investigated the microstructure and solute segregation in the melt pool boundary of orientation-controlled 316L austenitic stainless steel produced by laser powder bed fusion. The solidification cellular microstructures were visualized by solute segregation, and Mn-Si-O inclusions were observed along the lamellar boundaries and dislocation cell walls. The widening of cellular spacing at the bottom of the melt pool boundary was attributed to the decrease in cooling rate.
Article
Materials Science, Multidisciplinary
Takashi Ishikawa, Ryoji Sahara, Kaoru Ohno, Kyosuke Ueda, Takayuki Narushima
Summary: A new structural phase of anatase TiO2 codoped with C and N with a relatively low band gap was discovered. The stability of this phase was analyzed using density functional theory calculations, which also determined the defect states under different oxygen pressure conditions or oxygen chemical potential. The band gap narrowing mechanism was further studied using the all-electron GW approach, and it was found that the band gap could be controlled by varying oxygen pressure and doping states. Under intermediate oxygen pressure, TiO2 codoped with C and N exhibited a band gap of 2.28 eV, making it a potential visible-light-response photocatalyst.
COMPUTATIONAL MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Koji Hagihara, Toko Tokunaga, Kazuki Yamamoto, Michiaki Yamasaki, Tsuyoshi Mayama, Takumi Shioyama, Yoshihito Kawamura, Takayoshi Nakano
Summary: The influence of the volume fraction of the LPSO phase on the strengthening mechanisms in Mg/LPSO two-phase extruded alloys was investigated. The increase in the LPSO phase volume fraction enhances the yield stress of the alloys, but the increase is not monotonous. There are two large gaps in the rate of increase in the yield stress, indicating changes in the strengthening mechanisms. The kink-band strengthening mechanism is effective even in alloys with a low volume fraction of the LPSO phase.
MATERIALS TRANSACTIONS
(2023)
Article
Imaging Science & Photographic Technology
Keiya Sugiura, Toshio Ogawa, Yoshitaka Adachi, Fei Sun, Asuka Suzuki, Akinori Yamanaka, Nobuo Nakada, Takuya Ishimoto, Takayoshi Nakano, Yuichiro Koizumi
Summary: A modified SliceGAN architecture was proposed for generating high-quality synthetic 3D microstructure images of TYPE 316L material manufactured through additive methods. The quality of the generated 3D images was evaluated using an auto-correlation function, and it was found that maintaining high resolution and doubling the training image size were crucial for creating more realistic synthetic 3D images. To meet this requirement, a modified 3D image generator and critic architecture were developed within the SliceGAN framework.
JOURNAL OF IMAGING
(2023)
Article
Chemistry, Physical
Lei Wang, Masayuki Okugawa, Hirokazu Konishi, Yuheng Liu, Yuichiro Koizumi, Takayoshi Nakano
Summary: This paper proposes a novel method for wear-resistant TiNi coating through Ni plating and electron beam (EB) irradiation in an in situ synthetic approach. The feasibility of forming a TiNi phase by fusing the Ni plate with the CP-Ti substrate was investigated, and the optimal conditions for TiNi phase formation were determined. It is suggested that a more uniform TiNi layer can be achieved through multi-track melting under appropriate conditions, with potential for developing TiNi coatings with shape memory effects and pseudoelasticity.
Article
Biochemistry & Molecular Biology
Kenji Tanaka, Shuma Ohara, Tadaaki Matsuzaka, Aira Matsugaki, Takuya Ishimoto, Ryosuke Ozasa, Yukiko Kuroda, Koichi Matsuo, Takayoshi Nakano
Summary: The auditory brainstem response (ABR) is commonly used to assess auditory function, but determining the ABR threshold has been a challenge. Existing methods lack accuracy, efficiency, and convenience. We proposed an improved algorithm based on mutual covariance to objectively determine the ABR threshold. This method effectively reduced the burden on experimental animals and provided more efficient and accurate results.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
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)