Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
Hideharu Nakashima Last modified date:2020.01.06

Professor / Structural Material Science / Department of Advanced Materials Science and Engineering / Faculty of Engineering Sciences


Presentations
1. M. Mitsuhara, S. Yamasaki, H. Nakashima, K. Hagihara, T. Fujii, Microscopic observation of formation process of kink bands in Mg-Zn-Y alloy with LPSO phase, Mini-symposium: ”Elastic defects and structures. Modeling and experiments”, 2019.12.
2. S. Yamasaki, M. Mitsuhara, H. Nakashima, Creep behavior of ferritic heat resistant steel added with nitrogen, EPRI-123 HiMAT International Conference on Advances in High Temperature Materials, 2019.10.
3. M. Mitsuhara, S. Yamasaki, R. Arakane, R. Takao, H. Nakashima, Growth behavior of M23C6 carbides in high-Cr ferritic heat-resistant steels, EPRI-123 HiMAT International Conference on Advances in High Temperature Materials, 2019.10.
4. H. Nakashima, S. Yamasaki, M. Soushima, M. Mitsuhara, K. Hagihara, T. Fujii, Premonitory symptoms of kink deformation in Mg-Zn-Y alloy with LPSO phase, MFS 日露セミナー, 2019.09.
5. H. Nakashima, M. Mitsuhara, Materials for the sustainable development, International Conference on Sustainable Innovation, ICoSI 2019, 2019.07.
6. W. Li, S. Yamasaki, M. Mitsuhara, H. Nakashima, In-situ EBSD characterization of deformation behavior of primary alpha phase in Ti-6Al-4V, The 14th World Conference on Titanium,, 2019.06.
7. Influences of precipitates on creep fracture morphology of Ni-base Alloy 617.
8. Measurement of electron deflection in transmission electron microscopy observation of ferromagnetic materials.
9. Study of electron tomography observation conditions for magnetic materials.
10. S. Hata, Y. Shimada, T. Kajihara, K. Ikeda, H. Nakashima, K. Higashikawa, M. Inoue, T. Kiss, A. Matsumoto, H. Kitaguchi, H. Kumakura, T. Doi, J. H. Kim, S. X. Dou, Strategy of microstructural observation for the development of superconducting materials, 2013 MRS Spring Meeting & Exhibit, 2013.04.
11. S. Hata, R. Akiyoshi, M. Shimizu, M. Mitsuhara, K. Ikeda, H. Nakashima, Optimizing tilt-series data acquisition in dislocation tomography observations: methods and applications, 2013 TMS Annual Meeting & Exhibition, 2013.03.
12. Ryosuke IMAMURA, Satoshi HATA, Ken-ichi IKEDA, Hideharu NAKASHIMA, Shinji YAMAMOTO, Toshihiro TSUCHIYAMA, Daichi AKAMA, Satoshi MOROOKA, Mitsuhiro MURAYAMA, Deformation of Cu precipitates in cold-rolled Fe-Cu alloy, 14th Cross Straits Symposium on Energy and Environmental Science and Technology (CSS-EEST14), 2013.02.
13. T. Kajihara, Y. Shimada, S. Hata, K. Ikeda, H. Nakashima, A. Matsumoto, T. Mochiku, H. Kitaguchi, T. Doi, Formation of Bi,Pb-2223 and microstructural evolution in Pb-Ca-Cu deposited Bi-2212(001) single crystal by heat treatment, 25th International Symposium on Superconductivity, 2012.12.
14. S. Hata, Y. Shimada, T. Kajihara, K. Ikeda, H. Nakashima, A. Matsumoto, H. Kitaguchi, H. Kumakura, T. Doi, A. Yamamoto, J. Shimoyama, K. Kishio, K. Higashikawa, M. Inoue, T. Kiss, Recent findings in microstructural characters of superconducting wires and tapes, 25th International Symposium on Superconductivity, 2012.12.
15. S. Hata, R. Akiyoshi, M. Mitsuhara, K. Ikeda, Y. Miyajima, H. Nakashima, M. Kato, Electron tomography observations of dislocations near a symmetric tilt boundary in a deformed Mo bicrystal, The 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials (ISAEM-2012), 2012.11.
16. Ryutaro Akiyoshi, Ken-ichi Ikeda, Satoshi Hata, Hideharu Nakashima, Influence of precipitation morphology on tensile deformation behavior on Al-Mg-Si-Sc-Zr alloy, The 9th International Symposium on NOVEL CARBON RESOURCES SCIENCES, 2012.11.
17. T. Kiss, K. Higashikawa, A. Matsekh, M. Inoue, H. Tobita, M. Yoshizumi, T. Izumi, Y. Iijima, T. Saitoh, R. Yoshida, T. Kato, T. Hirayama, T. Kajihara, S. Hata, H. Nakashima, Multi-scale and multi-physics analysis of REBa2Cu3O7-δ coated conductors, Applied Superconductivity Conference 2012, 2012.10.
18. Y. Shimada, Y. Kubota, S. Hata, K. Ikeda, H. Nakashima, T. Doi, T. Fujiyoshi, Influences of microstructure on critical current properties in MgB2/Al film, Applied Superconductivity Conference 2012, 2012.10.
19. S. Hata, Y. Kubota, Y. Shimada, Y. Hishinuma, K. Ikeda, H. Nakashima, A. Kikuchi, Microstructural observation of MgB2 wires fabricated by low-temperature in-situ processes with Mg2Cu addition, Applied Superconductivity Conference 2012, 2012.10.
20. Junjie Shen, Kenichi Ikeda, Satoshi Hata, Hideharu Nakashima, A new deformation region and how low do you go? - "intrinsic deformation limit", Chinese Materials Congress 2012, CMC 2012, 2012.07, The creep deformation in pure aluminum was investigated using helicoid spring samples at room temperature, 298 K, and σ < 1.19 MPa. It was found that the stress exponent is n = 0, which means the creep behavior in this region is independent on applied stress but some physical properties of materials. The creep behavior was suggested to be controlled by surface diffusion based on the strongly effect of surface area on creep behavior only in this creep region (n = 0). The threshold creep rate, th ∑th, called "intrinsic deformation limit", decided by surface diffusion was suggested. This discovery provided a new perspective to understand the extremely slow deformation in the nature..
21. J. J. Shen, K. Ikeda, Satoshi Hata, Hideharu Nakashima, Room temperature creep and substructure formation in pure aluminum at ultra-low strain rates, TMS 2011 - 140th Annual Meeting and Exhibition, 2011.02, The creep behavior in pure aluminum has been investigated by helicoid spring creep tests at strain rates, ε, lower than 10-10 s -1 and room temperature, 298 K. It was found that the creep behavior at the very low ε depends strongly on grain sizes and impurity concentrations: in high-purity aluminum (5 N Al) with an average grain size of 24 μm, the stress exponent was n ∼ 1; while, when the average grain size was larger than 1600 μm, the stress exponent was n ∼ 5. Microstructural observation shows the formation of large dislocation cells, 10 μm. On the other hand, in commercial low-purity aluminum (2 N Al) with the average grain size of 25 μm, the stress exponent was n = 2. Microstructural observations revealed dislocations emitted from grain boundaries and the formation of lattice dislocation cells. To evaluate creep deformation mechanisms of the pure aluminum, stress change tests were conducted during creep tests. It was revealed that the deformation in the range of the stress exponent, n ∼ 5, was controlled by recovery driven by internal stress, σi, because instantaneous strains at stress increment were larger than that at stress reduction. While the deformation behaviors in the ranges of the stress exponents, n ∼ 1 and n = 2, were in viscous manner, because instantaneous strains at stress increment and reduction were in the same level. Based on those experimental results, the creep mechanisms have been discussed..
22. Hiroyuki Omura, Tatsuki Yonemaru, Jo Asada, Hideharu Nakashima, Weight saving in small engine and vehicle component by utilization of die cast creep resistant alloys, 2009.01, Magnesium alloys have been used and developed in applications for various motorcycle components and others such as cylinder head cover, crankcase and oil pan due to light weight, high specific strength and recycles ability. However, many of those alloys suffer from inferior die cast ability and high temperature properties, such as creep resistant. Ryobi limited has developed the creep resistant alloy in order to be utilized for the various motorcycle components and so forth. The properties of new die cast creep resistant alloy have been introduced. The targets for development of the properties of new alloy are the same creep resistant as aluminum die cast alloys and the same diecastability as ASTM magnesium alloys, such as AZ91D or AM60B alloys. Specific approaches of development with several types of evaluation have been performed for the purpose of fulfillment of this goal. This paper summarized the more detail of the mechanical properties, high temperature properties and die cast ability of new alloy..
23. H. Matsuo, Masatoshi Mitsuhara, K. Ikeda, Satoshi Hata, Hideharu Nakashima, Electron microscopy analysis of crack propagation behavior of alumina, Materials Science and Technology Conference and Exhibition, MS and T'08, 2008.10, Macroscopic features of crack propagation behavior in polycrystalline alumina (poly-alumina) and alumina single crystals (single-alumina) were analyzed by scanning electron microscopic electron back-scattered diffraction (SEM-EBSD) analysis. It was revealed that the intergranular fracture behavior is independent on grain boundary characters. When the cracks are propagated in the grains of poly- or single-alumina, zigzag cracks were produced. The zigzag cracks are composed of fracture surfaces formed along the cleavage planes. Microscopic features of fracture surfaces formed in a single-alumina were observed in detail by electron tomography combined with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). It was by visualized that the zigzag cracks were composed of flat and uneven fracture surfaces at a nm scale. The flat fracture surfaces and uneven ones were nearly parallel to the cleavage plane, {11̄02}, and the basal plane, {0001}, respectively..
24. Seiichiro Ii, Motoki Hishida, Naoki Takata, Ken Ichi Ikeda, Hideharu Nakashima, Nobuhiro Tsuji, Grain boundary structures of ARB processed aluminum, 4th International Conference on Nanomaterials by Severe Plastic Deformation, 2008.08, Grain boundary structures in the commercial purity aluminum (1100A1) highly deformed by the accumulative roll bonding (ARB) process was observed by using conventional transmission electron microscopy (CTEM) and high resolution transmission electron microscopy (HRTEM). In the low angle grain boundary with a tilt angle (2θ) of 2.1° consisted of the periodic dislocations array, the interval of those dislocations could be explained by the dislocation model for grain boundary. However, the dense dislocation region locally existed at the vicinity of the low angle boundary. On the other hand, we also observed the high angle grain boundary of which the common axis and 2θ was 〈110〉 and 125.9°, 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 129.52° around 〈110〉 and the additional dislocations to compensate the difference of the actual and geometrically coincided one..
25. H. Matsuo, K. Ikeda, Satoshi Hata, Hideharu Nakashima, Stress-induced phase transformation in the vicinity of Vickers indentations in 10mol% CeO2 doped tetragonal ZrO2 polycrystal, 12th International Conference on Martensitic Transformations, ICOMAT-08, 2008.06, The stress-induced martensitic phase transformation from a tetragonal (t) phase to a monoclinic (m) phase in a CeO2 doped tetragonal polycrystal (Ce-TZP) was investigated from the view pints of characters of lattice correspondences (LCs) between tand m-phases and morphology of m-phase. Electron back scattering diffraction (EBSD) analysis in the vicinity of Vickers indentations in Ce-TZP reveled that there were three LCs, named LCA (type A), LCB (type B) and LCC (type C), where fractions of the three LCs were 12%, 8% and 80%, respectively. Morphology of m-phase showing each of the three LCs were observed by transmission electron microscopy (TEM). A single variant of mphase with lamellar plate-shaped morphology (m-plates) was formed near the Vickers indentations. In contrast, two variants of m-phases with twin relationships (m-twins) were formed far from the Vickers indentations. The infinitesimal-deformation theory was adopted to calculate scalar magnitude of internal stress within the m-plates and m-twins for each type of the LCs. Irrespective of morphology of the m-phase, the internal stress field for type C is a tensile stress field. Regardless of the type of LCs, absolute values of internal stress in the m-plates are higher than those in the mtwins..
26. Masatoshi Mitsuhara, Yu Yoshida, Ken Ichi Ikeda, Hideharu Nakashima, Takashi Wakai, Effects of addition of V and NB on Ω in high CR ferritic steels, 6th Pacific Rim International Conference on Advanced Materials and Processing, PRICM 6, 2007.11, Creep tests and microstructural observations in several high Cr ferritic steels bearing V and Nb were carried out in order to investigate effects of addition of V and Nb on Ω, which is a coefficient of Ω method. Creep strength was improved with increasing the V content and was slightly lowered by increasing the Nb content. Ω in all the steels bearing V or Nb was lager than that in fundamental steel. The dependence of Ω on the amount of additions was different between V and Nb. In steels bearing V, Ω became larger with increasing V content. In steels bearing Nb, Ω became smaller. These results revealed that Ω corresponds to the creep strength, indicating that the value of Ω can be estimated using the strengthening effects of the additive element..
27. Masatoshi Mitsuhara, Yu Yoshida, Ken Ichi Ikeda, Hideharu Nakashima, Takashi Wakai, Effect of vanadium and niobium on creep strength in 10% chromium R steel analyzed by STEM-EDS, 2007 ASME Pressure Vessels and Piping Conference - 8th International Conference on Creep and Fatigue at Elevated Temperatures, PVP-2007/CREEP8, 2007.07, The effect of vanadium and niobium on creep strengthening was studied in 10% chromium steels. Eleven kinds of samples which varied the additive amounts of vanadium and niobium were prepared. From the creep deformation behavior of them, the threshold stresses were estimated. The distribution maps of precipitates were obtained by STEM-EDS. In a steel with added 0.06% vanadium where no particles were observed in the lath, creep strength was slightly increased, indicating that it was not strengthened by a particle hardening effect in the lath. Lump-shaped precipitates and film-shaped precipitates including chromium and vanadium, which were observed on lath boundaries in the steel with added vanadium, are expected to inhibit the lath boundaries from migrating. This inhibition is the mechanism of the improvement in the steel with added vanadium. In the case of steels with added niobium, creep strength was found to be increased by dispersion hardening due to fine precipitates in the lath. The threshold stress was quantitatively estimated depending on the particle spacing. The estimated threshold stress corresponded to the one obtained by the creep deformation behavior. These results revealed that vanadium and niobium each have a role in improving creep strength. In steels with added both vanadium and niobium, the effect on creep strength was expressed by the sum of the effects due to each element, which were the retardation of the lath boundary migrations and the pinning of the dislocations in the lath..
28. Hiroyuki Hayakawa, Satoshi Nakashima, Junichi Kusumoto, Daisuke Terada, Fuyuki Yoshida, Hideharu Nakashima, Evaluation of creep deformation mechanism of heat resistant steel by stress change test, 2007 ASME Pressure Vessels and Piping Conference - 8th International Conference on Creep and Fatigue at Elevated Temperatures, PVP-2007/CREEP8, 2007.07, In order to evaluate creep deformation mechanism of heat resistant steels, stress change tests were conducted during creep tests. In this study, it was confirmed that the dislocation behavior during the creep tests was in viscous manner, because no instantaneous plastic strain was observed at stress increments. Transient behavior was observed after stress changes for all kinds of steel in this work. Mobility of dislocation was evaluated by the observed backward creep behavior after stress reduction. Internal stress was evaluated by the change of creep rate in stress increment, and mobile dislocation density was evaluated with the estimated mobility of dislocation and the change of creep rate in stress increment. It was found that the variation of mobile dislocation density during creep deformation showed the same tendency as the variation of creep rate. Therefore mobile dislocation density is the dominant factor that influences the creep rate variation in creep deformation of heat resistant steels investigated in this work. The mobility of dislocation showed a good correlation with 1/T and it is related with the amount of solute Mo that is a solution strengthening element. Microstructure of crept specimens was observed by TEM to discuss the validation of these results..
29. Naoki Takata, Ken Ichi Ikeda, Hideharu Nakashima, Nobuhiro Tsuji, In-situ EBSP analysis of grain boundary migration during recrystallization in pure aluminum foils, 3rd International Conference on Recrystallization and Grain Growth, ReX GG III, 2007.06, Grain boundary mobility in preferential growth of cube grains ({100}〈001〉) was evaluated by in-situ electron back scattering diffraction pattern (EBSP) analysis in order to clarify the fundamental mechanism of primary recrystallization in pure aluminum foils of 99.9% purity thermo-mechanically processed in the industrial production route for aluminum foils for electrolytic capacitors. We have carried out the continuous EBSP measurements during recrystallization of the aluminum foils heated to various temperatures in the chamber of scanning electron microscopy (SEM). We have succeeded in dynamic observation of the preferential growth of cube grains by the in-situ EBSP analysis. The in-situ EBSP analysis could reveal the migration rate of grain boundaries surrounding the cube grains. It was clarified that the proportional relation between migration rate and annealing time was satisfied. The stored energy providing the driving force for the grain boundary migration during primary recrystallization could be estimated from the misorientation within the deformed grains. The mobility of the grain boundary could be evaluated using the measured grain boundary migration rate and stored energy. Then the activation energy could be estimated by the in-situ EBSP analysis at various temperatures ranging from 270°C to 310°C. The obtained activation energy was 124 kJ/mol, which approximately corresponded to that for the diffusion of impurity such as iron or silicon in aluminum. This suggested that the rate-determining process of the grain boundary migration of cube grains was impurity diffusion in the pure aluminum foils..
30. Ken Ichi Ikeda, Takahiro Yoshihara, Naoki Takata, Hideharu Nakashima, Relation between ridging and texture components in Al-Mg-Si alloy, 3rd International Conference on Recrystallization and Grain Growth, ReX GG III, 2007.06, Al-Mg-Si alloy is the suitable material for the automotive body application. However, it is found that a rope-like profile (ridging) develops when the Al-Mg-Si alloy sheet is stretched along the transverse direction. In this study, in order to clarify the formation process of ridging developed in Al-Mg-Si alloy, the relation between ridging and texture components of the sheet was investigated by 3D profile microscope and SEM/EBSD method. It was found that the ridging developed remarkably in the hot-rolled (at higher temperature) and annealed sheets. In ridging sample, there was the band of cube oriented grains (cube band). It was also found that the region of cube band corresponded to the ridges and valleys which caused a rope-like profile in the sheets. It could be thought that the difference of plastic deformability between cube-oriented grains and other oriented grains led to the development of ridging. This assumption is supported by the lower Taylor factor of cube oriented grains than other oriented grains. From these results, it was concluded that the development of ridging was strongly affected by the distribution of cube oriented grains..
31. Naoki Takata, Kousuke Yamada, Ken Ich Ikeda, Fuyuki Yoshida, Hideharu Nakashima, Nobuhiro Tsuji, Annealing behavior and recrystallized texture in ARB processed copper, 3rd International Conference on Nanomaterials by Severe Plastics Deformation, NanoSPD3, 2006.12, The recrystallization behavior and texture development in copper accumulative roll-bonding (ARB) processed by various cycles (2, 4 and 6 cycle) were studied by differential scanning calorimetry (DSC) analysis and SEM/EBSP method. The exothermic peaks caused by recrystallization appeared at 210 - 253°C in each sample. The peak positions shifted to lower temperature as the number of ARB cycles increased. This result indicated that the evolution of finer microstracture with increasing number of the ARB cycles enhanced the occurrence of recrystallization at lower temperature. The stored energy calculated from the DSC curve of the ARB processed copper increased with the increasing strains. During an annealing, the preferential growth of cube-oriented grains ({100}〈001〉) occurred in each sample. The recystallization behavior of ARB processed copper having low stacking fault energies was distinguished from that of so-called "recovery type" materials, i.e. aluminum and low carbon steels, which shows rather continuous changes in microstructure during annealing. The accumulated strains provided the driving force for the preferential growth, which was the same mechanism as the preferential growth in normally rolled copper. The sharpest cube texture developed in ARB processed copper by 4 cycles. The difference of cube texture development between 2 cycles and 4 cycles was caused by the distribution of cube-oriented regions which corresponded to the nucleation sites of recrystallized grains before annealing. More nanocystalline layers in the vicinity of bonded interfaces were distributed in ARB processed copper by 6 cycles than 4cycles. The nanocystalline structure could grow faster than the cube-oriented grains and led to the inhibition of sharp cube texture in the ARB processed copper by 6 cycles..
32. Ken Ichi Ikeda, Naoki Takata, Kousuke Yamada, Fuyuki Yoshida, Hideharu Nakashima, Nobuhiro Tsuji, Grain boundary structure in ARB processed copper, 3rd International Conference on Nanomaterials by Severe Plastics Deformation, NanoSPD3, 2006.12, Grain boundary structures in the Accumulative roll-bonding (ARB) processed copper (ARB-Cu) have been studied. The grain boundary structures were observed by high-resolution transmission electron microscopy (HRTEM). In order to clarify the difference between the grain boundaries in ARB-Cu and equilibrium boundaries, calculated atomic structure of symmetric tilt grain boundaries with <110> common axis <110> symmetric tilt grain boundary; <110> STGB) in Cu were used. The near 14° boundary in the ARB-Cu could be described by the dislocation model, but the dense dislocation region existed near the grain boundary. The high angle boundaries in ARB-Cu could be described by the structural units which were obtained by molecular dynamics (MD) simulation. Furthermore, in the 2 cycles and 6 cycles ARB-Cu (2cARB-Cu and 6cARB-Cu), the deformation twin boundaries could be observed and described by the structural unit. Therefore, it was concluded that the grain boundary structure in the ARB-Cu was not much different from the normal equilibrium grain boundary and explained by conventional dislocation and structural unit models..
33. Dong Wang, Seiichiro Ii, Ken Ichi Ikeda, Hideharu Nakashima, Hiroshi Nakashima, Photoluminescence evaluation of defects generated during temperature ramp-up process of SiGe-on-insulator virtual substrate fabrication, ICSICT-2006: 2006 8th International Conference on Solid-State and Integrated Circuit Technology, 2006.10, Defects generated during the temperature ramping process were evaluated by photoluminescence (PL) for Si/SiGe/Si-on-insulater structure, which is the typical structure for SiGe-on-insulator (SGOI) virtual substrate fabrication using the Ge condensation by dry oxidation. The free exciton peaks were clearly observed for the as grown wafers and decreased with the increase of annealing temperature. Defect-related PL signals at around 0.82, 0.88, 0.95 and 1.0 eV were observed and they also varied according to the annealing temperature and SiGe thickness. The defect-related PL signals were also correlated to dislocation-related defects by transmission electron microscopy (TEM)..