"published_papers" "Title(English)","Title(Japanese)","Author(s)(English)","Author(s)(Japanese)","Journal name(English)","Journal name(Japanese)","Volume","Number","First page","Last page","Date of publication","Peer reviewed/Not peer reviewed","Invited/Not invited","Publishing type","Language","ISSN","DOI","URL","Description(English)","Description(Japanese)" "Fatigue behavior of a Ni-Co base superalloy for turbine disc applications","Fatigue behavior of a Ni-Co base superalloy for turbine disc applications","小林信一, 長田 俊郎, 小野 嘉則, 井 誠一郎, 川岸 京子, 伊達 正芳, 大野 丈博","小林信一, 長田 俊郎, 小野 嘉則, 井 誠一郎, 川岸 京子, 伊達 正芳, 大野 丈博","Proceedings of the International Gas Turbine Congress 2019 Tokyo","Proceedings of the International Gas Turbine Congress 2019 Tokyo","","","172-1","172-4","2019","TRUE","","international_conference_proceedings","eng","","","","In this study, the crack initiation sites and crack propagation in fatigue-failed Ni-Co base superalloys, TMW-4M3, were investigated in detail. LCF lives of TMW-4M3 depended on the size of initiation site especially under low Δεtotal (0.8%). Three types of initiation sites were observed under Δεtotal =0.8%. Crystallographic facets were observed in 400℃-specimens. LCF life at 400℃ increase clearly in case where the grain size, especially as large as grain, was fine. However, the influence of grain size on LCF life at 650-725℃ was not clear unlike the case of 400℃. Blocky titanium rich carbides and particle clusters were observed in 650-725℃-specimens. These fatigue failure modes will be discussed.","" "Effect of Grain Boundary on the Plastic Deformation in Fe-C alloys","Effect of Grain Boundary on the Plastic Deformation in Fe-C alloys","Katsuya NAKANO, Kunio HAYASHI, Kengo TAKEDA, II, Seiichiro, OHMURA, Takahito","Katsuya NAKANO, Kunio HAYASHI, Kengo TAKEDA, II, Seiichiro, OHMURA, Takahito","Proceedings of The 5th International Symposium on Steel Science ","Proceedings of The 5th International Symposium on Steel Science ","","","219","222","2018-04-01","TRUE","","international_conference_proceedings","eng","","","","To investigate the effect of grain boundary and solute carbon on the plastic deformation, nanoindentation was performed on grain interior, and near grain boundaries for two types of steel, interstitial free steel (IF steel) and Fe-120 at.ppmC. Plotting of the obtained nanohardness against the inverse of square root of the distance from the indent to grain boundary shows Hall-Petch like relation. The slope of Hall-Petch like relation for IF steel is larger than that for Fe-120C, which is opposite result obtained by tensile test.","" "Effect of swirly segregation of Mo on omega phase precipitation behavior and tensile property of Ti-12Mo alloy","Effect of swirly segregation of Mo on omega phase precipitation behavior and tensile property of Ti-12Mo alloy","Satoshi Emura, Xiao Hua Min, Seiichiro Ii, Koichi Tsuchiya","Satoshi Emura, Xiao Hua Min, Seiichiro Ii, Koichi Tsuchiya","KEY ENGINEERING MATERIALS","KEY ENGINEERING MATERIALS","","","180","185","2013-05-01","TRUE","","international_conference_proceedings","eng","","10.4028/www.scientific.net/kem.551.180","","Mo is one of the important beta-phase stabilizing elements in Ti alloys, but Mo is prone to segregation. Recently, we have found swirly segregation of Mo in hot caliber rolled Ti-12~18 mass% Mo alloys. Isothermal aging of the alloys resulted in the heterogeneous precipitation of omega phase due to the swirly segregation of Mo, which led heterogeneous hardness distribution. In this study, we have investigated the effect of the swirly segregation and isothermal aging condition on room temperature tensile properties of Ti-12Mo alloy. Tensile strength has been slightly affected by the swirly segregation. However, total elongation has been extremely improved from 4~10 % to around 20 % in the samples with tensile strength of between 1000 and 1100 MPa. ","" "Microstructural Modification of Ti Alloys using Elemental Segregation","Microstructural Modification of Ti Alloys using Elemental Segregation","EMURA, Satoshi, MIN, Xiaohua, II, Seiichiro, TSUZAKI, Kaneaki, TSUCHIYA, Koichi","EMURA, Satoshi, MIN, Xiaohua, II, Seiichiro, TSUZAKI, Kaneaki, TSUCHIYA, Koichi","Proceedings of The 12th World Conference on Titanium","Proceedings of The 12th World Conference on Titanium","","","536","539","2012-06-01","TRUE","","international_conference_proceedings","eng","","","","Ti-25Al-14Nb-2Mo-1Fe alloy was hot forged and bar rolled at 1273 K. After the rolling, Nb and/or Mo rich region has distributed in a strange wavy and curled band-like structure. Using this segregation, we can obtain a locally-varied second phase precipitated microstructure. Room temperature tensile elongation value was improved from nearly 0 % to 6 %, which was attributed to this second phase precipitation manner. We also applied same kind of thermomechanical treatment on Ti-12Mo alloy, and successfully obtained same type of wavy and curled Mo segregated band-like structure. After solution treatment and aging, hard omega phase was precipitated inhomogeneously,which was due to the local variation of beta phase stability. Room temperature tensile elongation value was also improved.","" "Effect of high-pressure torsion deformation on isothermal omega phase in beta-Ti alloys","HPT加工がベータ型チタン合金の等温オメガ相に与える影響","TSUCHIYA, Koichi, FARJAMI, Susan, JIANG, Baozhen, MIN, Xiaohua, EMURA, Satoshi, II, Seiichiro","TSUCHIYA, Koichi, FARJAMI, Susan, JIANG, Baozhen, MIN, Xiaohua, EMURA, Satoshi, II, Seiichiro","Proceedings of the 12th World Conference on Titanium","Proceedings of the 12th World Conference on Titanium","","","584","587","2012-06-01","FALSE","","international_conference_proceedings","eng","","","","In the present investigation, the effect of HPT deformation on the microstructures and mechanical properties of beta-Ti alloys containing isothermal omega phase was studied. OM observations of cross-section on the HPT discs revealed numerous shear bands forms by HPT deformation. The density and thickness of the shear bands increased with increasing strain. White etching layer (WEL) appeared after 1 turn of HPT deformation and the WEL thickness increased with number of rotation. Microhardness measurements revealed that the hardness is lower inside the WEL (about 400 Hv) than the outside (about 460 Hv). The results suggest the decomposition of omega phase to beta or beta’’ phase. ","" "Experimental evaluation of local magnetic moment in 3d transi-tion metals by TEM/EELS technique","Experimental evaluation of local magnetic moment in 3d transi-tion metals by TEM/EELS technique","II, Seiichiro, MATSUNAGA Kyohei, HIRAYAMA Kyosuke, FUJII Hiromichi, TSUREKAWA Sadahiro","II, Seiichiro, MATSUNAGA Kyohei, HIRAYAMA Kyosuke, FUJII Hiromichi, TSUREKAWA Sadahiro","Conference Proceedings APMC 10 / ICONN 2012 / ACMM 22","Conference Proceedings APMC 10 / ICONN 2012 / ACMM 22","","","414-1","414-2","2012-02-01","FALSE","","international_conference_proceedings","eng","","","","Local magnetic moment in 3d transition metals such as iron, chromium and so on was experimentally evaluated from an intensity ratio of L2,3 edge obtained by TEM/EELS technique. The dependence of foil thickness on the white line ratio was also investigated. It was found that the thin foil thickness did not affect the white line ratio, although a background of the EELS spectra increased with increasing foil thickness. We also examined the relationship between the white line ratio and the magnetic moment for various 3d transition metals, and found that there was a linear relationship between them. This technique made it possible to experimentally evaluate the local magnetic moment near the grain boundary, for example, in 3d transition metals.","" "EELS measurement of local magnetic moments at grain boundaries in nickel and iron – effect of grain boundary character","EELS measurement of local magnetic moments at grain boundaries in nickel and iron – effect of grain boundary character","HIRAYAMA Kyosuke, MATSUNAGA Kyohei, II, Seiichiro, MORIZONO Yasuhiro, TSUREKAWA Sadahiro","HIRAYAMA Kyosuke, MATSUNAGA Kyohei, II, Seiichiro, MORIZONO Yasuhiro, TSUREKAWA Sadahiro","Conference Proceedings APMC 10 / ICONN 2012 / ACMM 22","Conference Proceedings APMC 10 / ICONN 2012 / ACMM 22","","","380-1","380-2","2012-02-01","FALSE","","international_conference_proceedings","eng","","","","We evaluated local magnetic moments at the grain interior and various grain boundaries in nickel and iron by electron energy loss spectroscopy (EELS). An enhancement of local magnetic moments around grain boundaries was observed with respect to the grain interior in nickel and iron. This enhancement was different according to grain boundary character: the increase in the local magnetic moments were higher at random grain boundaries than low-angle grain boundaries. On the other hand, the local magnetic moments less changed at (111)Σ3 coherent twin boundary in nickel. These results can be explained by the atomic free volume of grain boundaries, and are in good agreement with the results obtained by first-principles calculations.","" "Ductility Improvement in High Strength Ti-Mo Alloys by Transition of Deformation Mode","Ductility Improvement in High Strength Ti-Mo Alloys by Transition of Deformation Mode","MIN, Xiaohua, EMURA, Satoshi, II, Seiichiro, TSUCHIYA, Koichi, TSUZAKI, Kaneaki","MIN, Xiaohua, EMURA, Satoshi, II, Seiichiro, TSUCHIYA, Koichi, TSUZAKI, Kaneaki","Proceedings of The 12th World Conference on Titanium","Proceedings of The 12th World Conference on Titanium","","","1034","1037","2012-06-01","TRUE","","international_conference_proceedings","eng","","","","A transition of the deformation mode from the dislocation slip to the twinning was found to be an effective method for achieving a combination of high yield strength and large uniform elongation in the Ti-15Mo-5Zr and Ti-10Mo-2Fe alloys designed on the basis of the Mo equivalency. The deformation mode was dominated mainly by the dislocation slip at the initial stage of deformation and by the twinning in further deformation showing significant work hardening. This transition resulted in the coexistence of high strength and large uniform elongation. The twin formation was not uniform and was not seen in some of the grains even after the fracture. This heterogeneity is discussed based on the effects of the grain orientation and the segregation of alloying elements.","" "Hot Dynamic Densification of Materials by Utilizing Underwater Shock Wave","衝撃波を利用した材料の熱間固化成形","Ryuichi Tomoshige, Seiichiro Ii, Masahiro Fujita, Akira Chiba","Ryuichi Tomoshige, Seiichiro Ii, Masahiro Fujita, Akira Chiba","MATERIALS SCIENCE FORUM","MATERIALS SCIENCE FORUM","","","793","798","2012-01-01","TRUE","","international_conference_proceedings","eng","","10.4028/www.scientific.net/msf.706-709.793","","Hot dynamic densification method was developed by combining self-propagating high temperature synthesis (SHS) with explosively shock powder compaction technique. We aim to perform from synthesis to densification of TiB2-TiN system high temperature ceramic composites and TiB2-TiNi-Cu system functionally graded materials (FGMs) in one step. In TiN-TiB2 ceramic composites, they showed up to 95% of relative density. It was appeared by TEM observations that both the two phases joined tightly each other. The FGMs also were produced by the same technique. ","" "3D observation of isothermal omega phase in beta-Ti alloy by novel orthogonal FIB/SEM system","新型直交配置FIB/SEMによるベータチタン合金の等温オメガ相の3D観察","TSUCHIYA, Koichi, HARA, Toru, EMURA, Satoshi, MIN, Xiaohua, II, Seiichiro, TSUZAKI, Kaneaki, X.Man, K.Tanaka, A.Uemoto","TSUCHIYA, Koichi, HARA, Toru, EMURA, Satoshi, MIN, Xiaohua, II, Seiichiro, TSUZAKI, Kaneaki, X.Man, K.Tanaka, A.Uemoto","Proceedings of the 12th World Conference on Titanium","Proceedings of the 12th World Conference on Titanium","","","593","596","2012-06-01","FALSE","","international_conference_proceedings","eng","","","","The new FIB/SEM was used to observe omega phase particles in an isothermally aged Ti-15mass%Mo alloy. It was possible to observe the omega particles of less than 10 nm with a very high contrast by an in-lens secondary-electron (SE) detector. The omega particles appeared darker than the matrix in the SE images. This may be due to the lower Mo concentration in the omega phase particles than in the surrounding matrix. It was revealed that the shape of omega phase particles varies with the particle size. ","" "MICROSTRUCTURE OF BONDING INTERFACE IN EXPLOSIVELY WELDED METAL / CERAMIC CLAD","爆着法により作製した金属/セラミック クラッドにおける接合界面の微細組織","II, Seiichiro, IWAMOTO Chihiro, SATONAKA Shinobu, HOKAMOTO Kazuyuki, FUJITA Masahiro","II, Seiichiro, IWAMOTO Chihiro, SATONAKA Shinobu, HOKAMOTO Kazuyuki, FUJITA Masahiro","MATERIALS SCIENCE FORUM","MATERIALS SCIENCE FORUM","","","3775","3780","2010-01-01","TRUE","","international_conference_proceedings","eng","","","","Bonding interface in aluminum (Al) and silicon nitride (Si3N4) clad fabricated by explosive welding has been investigated by transmission electron microscopy (TEM). The nanocrystalline region was clearly observed at the interface between Al and Si3N4. Electron diffraction pattern and energy dispersive X-ray spectroscopy (EDS) measurements across the interface revealed that this nanocrystalline region consist of the only aluminum. ","" "Micro and Atomic structure of the interface in advanced materials fabricated by using high pressure with shock wave","衝撃波の利用により作製された先端材料の界面微細・原子構造","II, Seiichiro, Ryuichi TOMOSHIGE, Kazuyuki HOKAMOTO, Masahiro FUJITA","II, Seiichiro, Ryuichi TOMOSHIGE, Kazuyuki HOKAMOTO, Masahiro FUJITA","Proceeding of MC 2009","Proceeding of MC 2009","","","479","480","2009-09-01","FALSE","","international_conference_proceedings","eng","","","","爆発に伴い発生する衝撃エネルギーを利用して得られた複合材料の界面構造解析を行った.金属/セラミックスクラッド材の界面では,金属のナノ結晶化を確認することができた.これは,金属領域のの溶融・急冷凝固に伴いナノ結晶化した結果であると考えている.また,セラミックスの複合材料の粒界原子構造を調査したところ,粒界に高温強度劣化の原因となるガラス層は認められず結晶相同士が良好に接合されており,高温環境下でも特性が劣化することなく利用可能であることを示唆する結果が得られた.","" "Aging effect on martensitic transformation at cryogenic temperatures in Cu-Al-Mn alloy","Cu-Al-Mn合金における極低温のマルテンサイト変態に対する時効効果","II, Seiichiro, TSUCHIYA, Koichi, KOYANO Tamotsu","II, Seiichiro, TSUCHIYA, Koichi, KOYANO Tamotsu","ESOMAT 2009 - The 8th European Symposium on Martensitic Transformations","ESOMAT 2009 - The 8th European Symposium on Martensitic Transformations","","","02011-1","02011-4","2009-09-01","TRUE","","international_conference_proceedings","eng","","","","We have investigated the aging effect on the MT in Cu83-XAl17MnX alloys (X=10,12,14) by using differential scanning calorimeter (DSC) and electric resistivity (ER) measurements. In the Cu71Al17Mn12 aged at 373K for 0.6ks, we could find that MT occurred around 100K in ER measurement. And we also confirmed that the transformation temperatures increased with increasing of aging temperature and period, as the same of the other Cu-based shape memory alloys. In addition, an enthalpy of reverse transformation increased with increasing of only aging temperature. However, the enthalpy of reverse transformation of Cu71Al17Mn12 alloy aged at 423K for 0.6ks, whose As is 180K, was estimated about 50J/mol by DSC curve, and it was much less than that of Cu-Al-Mn alloy transformed around room temperature.","" "崇城大学における火薬を用いた先端材料合成および微細構造解析","Advanced materials synthesis and microstructural characterization using explosive at Sojo University","II, Seiichiro, Akio KIRA, Ryuichi TOMOSHIGE, Masahiro FUJITA","II, Seiichiro, Akio KIRA, Ryuichi TOMOSHIGE, Masahiro FUJITA","Materials Science Forum","Materials Science Forum","","","321","326","2008-03-01","TRUE","","international_conference_proceedings","eng","","","","In the research center for advances in impact engineering established in Sojo university, advanced materials have been synthesized by using shock wave and their microstructure has been investigated. An extremely high shock pressure and a dynamic hot compaction technique were developed, and the synthesis of the advanced materials and composites was succeeded. Transmission electron microscopy observations revealed unique microstructures of such materials obtained by our original advanced technique.","" "Grain boundary structures of ARB processed Aluminum","ARBプロセスを施したアルミニウムの粒界構造","II, Seiichiro, Motoki HISHIDA, Naoki TAKATA, Ken-ichi IKEDA, Hideharu NAKASHIMA, Nobuhiro TSUJI","II, Seiichiro, Motoki HISHIDA, Naoki TAKATA, Ken-ichi IKEDA, Hideharu NAKASHIMA, Nobuhiro TSUJI","Materials Science Forum","Materials Science Forum","","","716","721","2008-08-01","TRUE","","international_conference_proceedings","eng","","","","Grain boundary structures in the commercial purity aluminum (1100Al) highly deformed by the accumulative roll bonding (ARB) process was observed by using transmission electron microscopy. In the low angle grain boundary consisted of the periodic dislocations array, the interval of those dislocations could be explained by the dislocation model for grain boundary. On the other hand, we also observed the high angle grain boundary of which the common axis and 2θ was <110> and 125.9o, respectively. In this grain boundary, we could describe the boundary configuration in terms of the combination of the kite-shaped structure unit characterized by Σ11 coincidence boundary with the 2θ of 129.52o around <110>.",""