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Showing papers in "Materials Transactions in 2021"





Journal ArticleDOI
TL;DR: In this article, a review summarizes previous studies on the mechanism of cold-spray deposition and bonding, which can be understood as a mechanochemical phenomenon in part, and it is driven by the deformation of the particles and the resulting change in the chemical state of the particle surface, and stabilization by contact.
Abstract: Cold spray (CS) technology is a “solid-phase particle deposition process without melting”; however, it has been established as an additive manufacturing technology that can be applied beyond the framework of one field of thermal spraying. The scope of application of this technology has expanded to include ceramics and polymers. There are other solid particle deposition processes besides CS, such as aerosol deposition (AD), which differ in the material type, size, impact speed, and temperature of the target particles. We can expect that there is a common intrinsic mechanism through which solid-phase particles are joined and deposited in the solid phase. This review summarizes previous studies on the mechanism of cold-spray deposition and bonding, which can be understood as a mechanochemical phenomenon in part, and it is driven by the deformation of the particles and the resulting change in the chemical state of the particle surface, and stabilization by contact in a short time. When we understand these issues correctly, the optimal mechanical conditions (material size and collision conditions) for joining particles of various materials will be systematically understood, and it will be possible to perform different fabrication processes from thin films to additive manufacturing without melting various materials. [doi:10.2320/matertrans.T-M2021813]

10 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of electron-electron interactions on the metallic state of quasicrystals was theoretically studied and the extended Hubbard model on the Ammann-Beenker tiling was introduced.
Abstract: We theoretically study the effect of electron-electron interactions on the metallic state of quasicrystals. To address the problem, we introduce the extended Hubbard model on the Ammann-Beenker tiling as a simple theoretical model. The model is numerically solved within an inhomogeneous mean-field theory. Because of the lack of periodicity, the metallic state is nonuniform in the electron density even in the noninteracting limit. We clarify how this charge distribution pattern changes with electron-electron interactions. We find that the intersite interactions change the distribution substantially and in an electron-hole asymmetric way. We clarify the origin of these changes through the analyses in the real and perpendicular spaces. Our results offer a fundamental basis to understand the electronic states in quasicrystalline metals.

10 citations





Journal ArticleDOI
TL;DR: In this article, the classical and quantum magnetic states on an icosahedral cluster within the Heisenberg interactions of all bonds were investigated, where simulated annealing and numerical diagonalization were performed to obtain the quantum and classical ground states.
Abstract: Recent discovery of various magnetism in Tsai-type quasicrystalline approximants, in whose alloys rare-earth ions located on icosahedral apices are coupled with each other via the Ruderman--Kittel--Kasuya--Yosida interaction, opens an avenue to find novel magnetism originating from the icosahedral symmetry. Here we investigate classical and quantum magnetic states on an icosahedral cluster within the Heisenberg interactions of all bonds. Simulated annealing and numerical diagonalization are performed to obtain the classical and quantum ground states. We obtain qualitative correspondence of classical and quantum phase diagrams. Our study gives a good starting point to understand the various magnetism in not only quasicrystalline approximants but also quasicrystals.

8 citations






Journal ArticleDOI
TL;DR: In this paper, the authors presented the results of a study at the Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan and the Synchrotron Light Application Center, Saga University, Saga 840-8502.
Abstract: 1Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan 2Magnesium Research Center, Kumamoto University, Kumamoto 860-8555, Japan 3Synchrotron Light Application Center, Saga University, Saga 840-8502, Japan 4Department of Materials Science and Engineering, Kyushu University, Fukuoka 819-0395, Japan 5Department of Mechanical Engineering and Materials Science, Yokohama National University, Yokohama 240-8501, Japan 6Japan Synchrotron Radiation Research Institute, Hyogo 679-5198, Japan

Journal ArticleDOI
TL;DR: In this article, the shape of melt pool was simulated by analyzing the heat transfer using apparent heat conductivity when the penetration of laser beam through keyholes was taken into consideration because of the evaporation and accompanying convections.
Abstract: Metal additive manufacturing (AM) technologies are attracting attentions not only as a fabrication process of complicated threedimensional parts but also as microstructure controlling processes. In powder bed fusion (PBF)-type AM, crystallographic texture can be controlled by scanning strategies of energy beam. To optimize microstructures, computer simulations for predicting microstructures play very important roles. In this work, we have developed simulation programs to explain the mechanism of the crystal orientation control. First, we simulated the shape of melt pool by analyzing the heat transfer using apparent heat conductivity when the penetration of laser beam through keyholes was taken into consideration because of the evaporation and accompanying convections. It was assumed that the primary crystal growth direction can be determined by the temperature gradient, and the crystals grow keeping the growth direction as generally recognized. The shapes of simulated melt pools agree well with experimental observations. The modified cellular automaton simulations successfully reproduced two typical textures with different preferential orientations along the building directions of ©100a and ©110a when the bidirectional scanning with and without a rotation of 90°, respectively, was accomplished between the layers. [doi:10.2320/matertrans.MT-M2021009]

Journal ArticleDOI
TL;DR: AIST's Advanced Coating Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8564, Japan as mentioned in this paper, Tokyo 135-8548, Japan
Abstract: 1Graduate School, Shibaura Institute of Technology, Tokyo 135-8548, Japan 2Advanced Coating Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8564, Japan 3Shibaura Institute of Technology, Tokyo 135-8548, Japan 4Advanced Coating Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan



Journal ArticleDOI
TL;DR: In this paper, the authors proposed a method for the synthesis of structural materials based on materials processing and applied it to the design of a structural material for the construction of a bridge.
Abstract: 1Department of Mechanical Engineering, Faculty of Science and Engineering, Kindai University, Higashiosaka 577-8502, Japan 2Department of Materials Processing, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan 3Division of Materials Science and Engineering, Graduate School of Engineering, Osaka University, Suita 565-0871, Japan 4Research Center for Structural Materials, National Institute for Materials Science, Tsukuba 305-0047, Japan