九州大学-研究者情報 [赤嶺大志 (助教) 総合理工学研究院物質科学部門]

赤嶺大志（あかみねひろし）

データ更新日：2024.04.02

助教　／　総合理工学研究院物質科学部門

原著論文

1.	Akira Heima, Yuri Shinohara, Hiroshi Akamine, Minoru Nishida, Tomonori Inamura, Peculiar martensitic microstructure and dislocation accumulation behavior in Ti-Ni-Cu shape memory alloys almost satisfying the triplet condition, Acta Materialia, 269, 119823, 2024.03.
2.	Masaru Itakura, Hiroki Kontani, Hiroshi Akamine, Kazumasa Fujimura, Takahiko Iriyama, Coercivity saturation in Nd-Fe-B sintered magnets treated by grain boundary diffusion process of Tb-Ni-Al alloy, Journal of Magnetism and Magnetic Materials, 10.1016/j.jmmm.2023.171698, 591, 171698, 2024.02.
3.	Zheyuan Liang, Kakeru Ninomiya, Hiroshi Akamine, Ryotaro Arai, Sumio Kise, Minoru Nishida, Maiko Nishibori, X-ray absorption spectroscopy study of the local atomic structure in a ductile Cu-Al-Mn shape memory alloy, Materialia, 10.1016/j.mtla.2023.101918, 101918, 2023.09.
4.	A. S. K. Mohammed, R. Sidharth, W. Abuzaid, H. Akamine, M. Nishida, H. Sehitoglu, Orientation Relationships in FeMnNiAl Governed by Martensitic Substructure, Shape Memory and Superelasticity, 10.1007/s40830-023-00458-6, 2023.08.
5.	Hiroshi Akamine, Alimzhan Kalbekov, Takumi Higashizono, Mitsuhiro Matsuda, Satoshi Hata, Minoru Nishida, Hydrogen-induced phase with martensitic-like characteristics in Ti-Ni shape memory alloys, Journal of Alloys and Compounds, 10.1016/j.jallcom.2023.171470, 965, 171470, 2023.07, It has been reported that functional and mechanical properties of Ti-Ni shape memory alloys could be degraded by hydrogen absorption. Many studies have indicated the formation of a hardened layer on the surface in hydrogen-absorbed Ti-Ni alloys. However, the underlying microstructural features and their impact on the functional and mechanical properties remain unclear. In the present study, ex situ and in situ electron microscopy characterizations of the high-hardness layer in a hydrogen-charged Ti-Ni alloy were performed for the first time. Electron diffraction and atomic resolution imaging revealed that the hardened layers have an orthorhombic structure with a four-layer stacking sequence and a martensitic-like crystallographic nature such as lattice correspondence including 12 variants of the orthorhombic phase against each orientation of the parent cubic (B2) phase. In situ and ex situ observations in an electron microscope confirmed that the orthorhombic phase undergoes athermal transformation upon cooling and stress- and/or strain-induced transformation upon deformation, which further characterizes the martensitic-like nature of this phase. The effect of hydrogen on the original phase transformation from the cubic (B2) to the monoclinic (B19′) structure is also discussed..
6.	M. Matsuda, N. Maeda, K. Onaka, H. Akamine, M. Nishida, Effect of Hf on the lattice invariant shear and self-accommodation of martensite in Ti–Ni–Hf alloys, Journal of Materials Science, 10.1007/s10853-023-08707-w, 58, 10896, 2023.07.
7.	H. Akamine, A. Heima, Y. Soejima, M. Mitsuhara, T. Inamura, M. Nishida, Where and when are dislocations induced by thermal cycling in Ti–Ni shape memory alloys?, Acta Materialia, 244, 118588, 2023.01, Systematic experiments were performed to determine where and when dislocations are induced during the thermal cycling of Ti–Ni shape memory alloys. The decrease in transformation temperatures upon thermal cycling became less pronounced with increasing Ni concentration, which was supported by the dislocation densities estimated from scanning transmission electron microscopy observations. The arrangement of transformation-induced dislocations after the 1st thermal cycle reproduced the self-accommodation structure of B19ʹ martensite. Three-dimensional visualization revealed that the complex spiral appearance of the dislocations after the 1st thermal cycle was attributable to the duplicated projection of relatively simple elongated dislocation loops aligned in the depth direction parallel to 〈111〉B2 along {110}B2. No dislocations were observed along the twin boundary in the initially transformed martensite, whereas there were numerous dislocations parallel to the trace of the {110}B2 planes in the martensite formed upon the 2nd thermal cycle. The results suggest that the transformation-induced dislocation loops were generated during the reverse transformation rather than the forward transformation. The possible source site of the transformation-induced dislocations is also discussed..
8.	S. Zhu, H. Akamine, Y. Nagahata, T. Tojigamori, H. Miki, Y. Zhang, T. Tokunaga, S. Iikubo, Microstructure control and its observation of rapid solidification Cu–La alloy for the development of fluoride-ion batteries, Journal of Alloys and Compounds, 930, 167447, 930, 167447, 2023.01.
9.	Francesco Della Porta, Akira Heima, Yuri Shinohara, Hiroshi Akamine, Minoru Nishida, Tomonari Inamura, Triplet condition: A new condition of supercompatibility between martensitic phases, Journal of the Mechanics and Physics of Solids, https://doi.org/10.1016/j.jmps.2022.105050, 169, 105050, 2022.09.
10.	Ryunosuke Nakamura, Hidetaka Kasai, Tomoki Fujita, Hiroshi Akamine, Satoshi Hata, and Eiji Nishibori, Critical Length for Lattice Expansion of SnO2 Nanorods and Nanosheets: Implications for Lithium-Ion Batteries, Applied Nano Materials, https://doi.org/10.1021/acsanm.1c02615, 4, 9938-9944, 2021.09.
11.	Mitsuhiro Matsuda, Kodai Kiwaki, Hiroshi Akamine, Minoru Nishida, Effect of Hf on the microstructure and martensitic transformation behavior in Ti–Pd–Hf alloy, Journal of Alloys and Compounds, https://doi.org/10.1016/j.jallcom.2022.165491, 917, 165491, 917, 165491, 2022.05.
12.	Masaru Itakura, Koichi Sugiyama, Hiroshi Akamine, Minoru Nishida, Michihide Nakamura, Tetsuhiko Mizoguchi, Takahiko Iriyama, Suppression mechanism of abnormal grain growth by Zr addition in pressless processed Nd-Fe-B sintered magnets, Journal of Alloys and Compounds, https://doi.org/10.1016/j.jallcom.2021.161244, 887, 161244, 2021.12, Microstructures of pressless processed (PLP) Nd-Fe-B sintered magnets with and without Zr addition were investigated by scanning electron microscopy and scanning/transmission electron microscopy. In the Zr-free magnet, huge polygonal abnormal grains (AGs) about 100 times larger than the normal grain size were generated by PLP sintering at 975 °C. Electron backscattered diffraction analysis revealed that the PLP sintered magnet had a biaxial oriented texture of fine Nd2Fe14B grains with the orientation of the AGs significantly deviated from the biaxial oriented grains. By adding a small amount of Zr, fine plate-like Zr-B precipitates with a long period stacking ordered structure derived from the ZrB2 phase formed on the growth surfaces of Nd2Fe14B grains with a crystallographic orientation relationship. There were two Nd-rich grain boundary (GB) phases, namely, orthorhombic Nd3(Co, Cu) and metastable CaF2-NdO2, which became liquid during sintering. The boron consumption associated with the formation of Zr-B precipitates increased the Nd-rich GB phases, resulting in a homogeneous distribution of the liquid phase around the Nd2Fe14B grains. Therefore, the addition of Zr effectively suppressed the abnormal grain growth during PLP sintering owing to the pinning effect of the Zr-B precipitates and the formation of a homogeneous liquid phase distribution..
13.	M. Egilmez, O. Batal, W. Abuzaid, Z. Salman, M. Alkhader, H. Akamine, M. Nishida, J. W. A. Robinson, Superconductivity in Ti67Zr19Nb11.5Sn2.5 shape memory alloy, Physical Review Materials, https://doi.org/10.1103/PhysRevMaterials.5.074802, 5, 074802, 2021.07, Shape memory alloys (SMAs) exhibit unique functionalities due to their superelastic and shape memory properties. The ability to program and alter their shapes following a thermomechanical stimulus makes them highly important materials for a vast number of applications in the aerospace, automotive, biomedical, and robotic sectors. Research on SMAs has largely focused on metallurgical, mechanical, structural, or phase transformation properties. Here, we investigate the electrical, magnetic, and thermodynamic properties of the biocompatible SMA, Ti67Zr19Nb11.5Sn2.5 (at. %). In particular, we report the discovery of a superconducting phase transition with a critical temperature of 4.65 K with 0 K critical magnetic fields of Hc1=13.7mT and Hc2=9.2T. From the temperature dependence of the specific heat and local magnetic field measurements using transverse field muon spin rotation, we also determine a superconducting coherence of 6 nm and a London penetration depth of 776 nm. The results are key towards the development of cryogenic electrical device applications of SMA materials..
14.	H. Akamine, M. Mitsuhara, M. Nishida, V. Samaee, D. Schryvers, G. Tsukamoto, T. Kunieda, H. Fujii, Precipitation behaviors in Ti-2.3 wt.%Cu alloy during isothermal and two-step aging, Metallurgical Materials Transactions A, https://doi.org/10.1007/s11661-021-06265-x, 52, 7, 2760-2772, 2021.07.
15.	K. Tsuzaki, M. Koyama, R. Sasaki, K. Nakafuji, K. Oie, A. Shibata, T. Gondo, H. Miyazaki, H. Akamine, M. Nishida, Novel -75°C cooling stage: Application for martensitic transformation in steel, Microscopy, 70, 250-254, 2021.04.
16.	Y. Soejima, A. Heima, H. Akamine, T. Inamura, M. Nishida, Comparison of in situ SEM and TEM observations of thermoelastic martensitic transformation in TiNi shape memory alloy, Materials Transactions, 10.2320/matertrans.MT-M2020219, 61, 11, 2107-2114, 2020.09, ©2020 The Japan Institute of Metals and Materials. To quantitatively understand the thin foil effect in in situ observations of the B2 to B19A transformation in TiNi alloy, the microstructure of the B19A martensite in thin foil and bulk specimens was compared. The transformation temperatures decreased with decreasing specimen thickness. There were large habit plane variants more than several tens of micrometers in size in the area of the specimen less than 10μm thick. The critical thicknesses for reproducing the transformation behavior in the bulk material was about 20μm based on the self-accommodation morphology and 4 μm based on the twin width ratio of the (011) type II twin..
17.	Fumiyoshi Yamashita, Yasunori Ide, Hiroshi Akamine, Kouji Ishikawa, Minoru Nishida, Effect of C/O Ratio on Phase Change and Stability of Inclusions in Ti–Ni Alloys Fabricated by a Commercial Production Process, Shape Memory and Superelasticity, 10.1007/s40830-020-00302-1, 6, 3, 354-364, 2020.09, © 2020, ASM International. The effects of carbon/oxygen concentrations in Ti-51 at.% Ni on the morphology and phase changes of inclusions in a commercial wire manufacturing process were investigated. Whereas cast material fabricated with a carbon to oxygen mass concentration ratio (C/O ratio) of 1.0–1.5 were found to contain single-phase Ti(C,O), when hot working was performed, some of the Ti(C,O) exhibited a phase change to Ti2Ni(O), and a mixed phase structure was found in specimens with a C/O ratio of less than 1.5. On the other hand, single-phase Ti(C,O) was found to remain in the wire produced from the specimens with a C/O ratio of 1.5..
18.	喜瀬純男, 赤嶺大志, 平間慧, 重松和磨, 高松凌, 西田稔, 荒木慶一, 大森俊洋, 貝沼亮介, 結晶粒界性格制御によるCu-Al-Mn超弾性合金板の耐応力腐食割れ改善, 銅と銅合金, 59, 2020.08.
19.	Wei Chen Wen, Yuta Nagatomi, Hiroshi Akamine, Keisuke Yamamoto, Dong Wang, Hiroshi Nakashima, Interface trap and border trap characterization for Al2O3/GeOx/Ge gate stacks and influence of these traps on mobility of Ge p-MOSFET, AIP Advances, 10.1063/5.0002100, 10, 6, 2020.06, © 2020 Author(s). Interface traps (ITs) and border traps (BTs) in Al2O3/GeOx/p-Ge gate stacks were characterized using deep-level transient spectroscopy. Through evaluating the gate stacks with different GeOx thicknesses, the respective BTs in Al2O3, the Al2O3/GeOx interface region, and GeOx were detected. The density of ITs (Dit) near the midgap is lower in the metal-oxide-semiconductor (MOS) capacitors with thicker GeOx, while Dit near the valence band is lower in the MOS capacitor with thinner GeOx. The density of BTs (Nbt) in Al2O3 (6-9 × 1017 cm-3) is lower than those in GeOx (∼2 × 1018 cm-3), and the highest Nbt (∼1 × 1019 cm-3) was found in the Al2O3/GeOx interface region. Ge p-channel metal-oxide-semiconductor field-effect-transistors (MOSFETs) with Al2O3/GeOx/p-Ge gate stacks were fabricated and analyzed. We confirmed that the ITs and the BTs near the valence band edge of Ge affect the effective mobility of Ge p-MOSFETs in the high-field region..
20.	Ryusei Oka, Keisuke Yamamoto, Hiroshi Akamine, Dong Wang, Hiroshi Nakashima, Shigeomi Hishiki, Keisuke Kawamura, High interfacial quality metal-oxide-semiconductor capacitor on (111) oriented 3C-SiC with Al2O3 interlayer and its internal charge analysis, Japanese Journal of Applied Physics, 10.35848/1347-4065/ab6862, 59, SG, 2020.04, © 2020 The Japan Society of Applied Physics. Metal-oxide-semiconductor (MOS) capacitors with various gate dielectrics were fabricated on (111) oriented n-type 3C-SiC. Deposited SiO2 by sputtering without an interlayer (IL) and thermally grown SiO2 show deteriorated capacitance-voltage (C-V) characteristics and high interface trap density (D it) over 1011-1012 cm-2 eV-1. By inserting an IL, C-V and leakage current characteristics are improved. In particular, an atomic layer deposited (ALD) Al2O3-IL is suitable for 3C-SiC, which successfully achieved low D it in the order of 1010 cm-2 eV-1. MOS capacitor with the same gate dielectric on n-Si shows contradictory characteristics. Structural analysis shows it is considered the flat and uniform interface at Al2O3/3C-SiC leads good electrical characteristics. The 3C-SiC MOS capacitor with Al2O3-IL showed slightly negative flatband voltage and it is induced by negative interfacial dipole generated at the Al2O3/3C-SiC interface. This 3C-SiC MOS structure can be fabricated at low process temperature (
21.	Z. N. Zhou, H. Akamine, J. Li, L. Yang, T. Higashizono, Q. D. Hu, M. Nishida, J. G. Li, Tuning martensite transformation behavior and magneto-caloric effect in Ni44Mn36In14Co6 alloy through doping the fifth element Cu, Journal of Alloys and Compounds, 10.1016/j.jallcom.2019.153150, 817, 2020.03, © 2019 Elsevier B.V. The martensite transformation (MT) behavior and magneto-caloric effect (MCE) in polycrystalline Ni44Mn36In14Co6 alloy were tuned by doping the fifth element, 2 at.% Cu. The process of heat-induced MT was observed by in-situ scanning electron microscopy and the magnetic-field-induced reversible MT was confirmed by magnetic properties test near room temperature. A large magnetization change (ΔM, 111emu/g), relatively high sensitivity to magnetic fields (3.8 K/T), a large MCE (33.7J kg−1 K−1) and the two-way magnetic-field-induced transformation were attained around the MT. The combination properties in the Ni42Mn36In14Co6Cu2 alloy are instructive for the development of high-performance magnetic refrigeration and intelligent actuator materials..
22.	Hiroshi Akamine, Yohei Soejima, Tadaaki Nakamura, Sahar Farjami, Takashi Fukuda, Tomoyuki Kakeshita, Minoru Nishida, Isothermal martensitic transformations in an aged Ni-rich Ti-Ni alloy containing coherent Ti3Ni4 particles, Materials Transactions, 2020.03, The time dependence nature of B2 (ordered cubic) to R (trigonal) and R to B19A (monoclinic) martensitic transformations in an aged Ni-rich Ti-Ni alloy was investigated by electrical resistivity measurements. Both B2 to R and R to B19A transformations exhibit time dependence nature in the aged alloy containing coherent lenticular Ti3Ni4 precipitates with an average diameter of about 110 nm. However, the successive B2-R-B19A isothermal transformation is not detected by electrical resistivity measurements. The isothermal R-B19A transformation is visualized by in situ scanning electron microscopy (SEM) observations..
23.	K. Yamamoto, K. Nakae, H. Akamine, D. Wang, H. Nkashima, M.M. Alam, K. Sawano, Z. Xue, M. Zhang, Z. Di, Conduction Type Control of Ge-on-Insulator: Combination of Smart-Cut™ and Defect Elimination, ECS Transactions, 93, 73-77, Vol. 93, pp. 73-77., 2019.10.
24.	Rina Takizawa, Hiroshi Akamine, Masaru Itakura, Minoru Nishida, Nobuhiro Katayama, Koichiro Morimoto, Influence of desorption recombination temperatures on microstructure and coercivity of HDDR-processed anisotropic Nd-Fe-B magnet powders, Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals, 10.2320/jinstmet.J2017061, 82, 4, 121-124, 2018.01, [URL], In the hydrogenation decomposition desorption recombination(HDDR)processed Nd Fe Co B Al Ga Zr magnet powders, influence of the desorption recombination(DR)temperatures on the microstructures was investigated by high resolution scanning electron microscopy and scanning transmission electron microscopy. By applying the DR treatment under high vacuum(DR Step 2)at relative low temperatures about 973 K, we can obtain the excellent texture in which the average size of Nd₂Fe₁₄B grains is refined to about 240 nm and the grain boundary(GB)phase is uniformly dispersed around the Nd₂Fe₁₄B grains. In the GB phase, furthermore, the Nd composition increases and the(Fe, Co)composition decreases drastically with decreasing the DR temperatures, and then Nd rich GB phase with more than 65 at.%Nd can be formed at 973 K. At 973 K, however, the region with unformed GB phase is remained about 10% of the specimen, which leads to deterioration of the coercivity. It was found that the gently DR treatment is very effective not only for increasing the coercivity but also for improving the squareness in demagnetization curve..
25.	Hiroshi Akamine, So Okumura, Sahar Farjami, Yasukazu Murakami, Minoru Nishida, Imaging of surface spin textures on bulk crystals by scanning electron microscopy, Scientific Reports, 10.1038/srep37265, 6, 2016.11, © The Author(s) 2016. Direct observation of magnetic microstructures is vital for advancing spintronics and other technologies. Here we report a method for imaging surface domain structures on bulk samples by scanning electron microscopy (SEM). Complex magnetic domains, referred to as the maze state in CoPt/FePt alloys, were observed at a spatial resolution of less than 100 nm by using an in-lens annular detector. The method allows for imaging almost all the domain walls in the mazy structure, whereas the visualisation of the domain walls with the classical SEM method was limited. Our method provides a simple way to analyse surface domain structures in the bulk state that can be used in combination with SEM functions such as orientation or composition analysis. Thus, the method extends applications of SEM-based magnetic imaging, and is promising for resolving various problems at the forefront of fields including physics, magnetics, materials science, engineering, and chemistry..
26.	Hiroshi Akamine, Masatoshi Mitsuhara, Minoru Nishida, Developments of coal-fired power plants: Microscopy study of Fe-Ni based heat-resistant alloy for efficiency improvement, Evergreen, 3, 2, 45-53, 2016.09, Anthropogenic emissions of greenhouse gases are one of the possible reasons for the global warming. Coal consumption is predicted to be increased over several decades due to increasing demands in some countries. In the medium-term energy strategy, coal-fired power plants thus need to be developed. For this purpose, developments of new heat-resistant alloys that can stand severe steam conditions in advanced power plants are essential. A potential alloy was studied, which revealed that hardness of the alloy is related to the distribution of precipitates. The development of the alloy is also vital to make the power plants more economically competitive..
27.	H. Akamine, K.H.W. van den Bos, N. Gauquelin, S. Farjami, S. Van Aert, D. Schryvers, M. Nishida, Determination of the atomic width of an APB in ordered CoPt using quantified HAADF-STEM, Journal of Alloys and Compounds, 10.1016/j.jallcom.2015.04.205, 644, 570-574, 2015.09.
28.	Hiroshi Akamine, Sahar Farjami, Hidetsugu Sakaguchi, Minoru Nishida, Phase-field simulation of magnetic field-induced preferential variant selection in A1-L1₀ disorder-order transformation, International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2015, PTM 2015 PTM 2015 - Proceedings of the International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2015, 425-426, 2015.06, Near-equiatomic Co-Pt, Fe-Pd and Fe-Pt alloys undergo cubic-tetragonal disorder-order transformation and form three orientation variants. It has been reported that magnetic fieldinduced preferential nucleation of one variant in the initial stage of ordering introduces preferential growth of the same variant in the later magnetic field-free stage [1]. In this study, the effect of preferential nucleation on microstructure evolution in the later stage is studied by phasefield method. The results indicate that the increase in fraction of preferential variant depends on nucleation ratio between the variants, and the stress field originated from the macroscopic shape deformation is the most possible factor affecting preferential growth in the later stage..
29.	Hidetsugu Sakaguchi, Hiroshi Akamine, Domain wall dynamics in ginzburg-landau-type equations with conservative quantities, Journal of the Physical Society of Japan, 10.7566/JPSJ.83.064006, 83, 6, 2014.06, © 2014 The Physical Society of Japan. In the Ginzburg-Landau equation, there are domain walls connecting two metastable states. The dynamics of domain walls has been intensively studied, but there remain still unsolved but crucial problems even for a single domain. We study the domain wall dynamics in three different Ginzburg-Landau-type equations satisfying conservation laws. In a modified ø4 model satisfying the law of energy conservation and the Lorentz invariance, the motion of a domain wall is accelerated and the velocity approaches its maximum. In a one-dimensional model of eutectic growth, the order parameter is conserved and a domain wall connecting a metastable uniform state and a spatially periodic pattern appears. We try to find a selection rule for the wavelength of a spatially periodic pattern. In a model equation for martensitic transformation, a domain wall connecting a uniform metastable state and a zigzag structure appears which propagates at a high velocity..
30.	Yutaro Ueda, Takeshi Daio, Tomohiro Yoshida, Hiroshi Akamine, Aki Tominaga, Toshihiro Okajima, Tsuyoshi Yoshitake, Crystalline-structural evaluations of cubic AlN thin films heteroepitaxially grown on sapphire (0001) by pulsed laser deposition, Japanese Journal of Applied Physics, 10.7567/JJAP.52.08JE03, 52, 8 PART 2, 2013.08, Cubic β-AlN thin films with different thicknesses were grown on sapphire (0001) in nitrogen atmosphere by pulsed laser deposition with sintered AlN targets, and their film structures were evaluated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that β-AlN layers with a lattice constant of 7.89 A are epitaxially grown on sapphire (0001) with a relationship of β-AlN(111)[111̄]\|\| Al2O 3(0001)[11̄00] at film thicknesses of less than 20 nm, and at larger thicknesses, polycrystalline β-AlN grains are grown on the epitaxial β-AlN layers in the Stranski-Krastanov (SK) mode. © 2013 The Japan Society of Applied Physics..
31.	Hiroshi Akamine, Sahar Farjami, Masatoshi Mitsuhara, Minoru Nishida, Takashi Fukuda, Tomoyuki Kakeshita, Electron microscopy study of preferential variant selection in CoPt alloy ordered under a magnetic field, Materials Transactions, 10.2320/matertrans.MAW201313, 54, 9, 1715-1718, 2013.08, [URL], Transmission electron microscope (TEM) and scanning transmission electron microscope (STEM) observations were carried out to investigate microstructure formation and variant selection process in L1₀-type ordered CoPt alloy upon a two-step ordering heat-treatment. The first step corresponds to nucleation process carried out under a magnetic field of 10 T and the second step represents growth process without magnetic field. After the first step of ordering, ordered domains of about 5 nm in size were observed and fraction of the preferred variant with the c-axis parallel to applied magnetic field was slightly higher than that of the other two variants. Formation of tweed microstructure along {011}L1₀ was confirmed at the initial stage of ordering. This structure is considered to be derived from the periodic alignment of interface between two ordered variants with twin relation. At the early stage of the second step of ordering, numerous micro-twins were formed through tweed microstructure and the volume fraction of the preferred variant was increased accompanying with modulation of twins, while that of other two variants was decreased. After the second step of ordering, the twins were vanished and single variant was obtained..
32.	Sausan Al-Riyami, Hiroki Gima, Hiroshi Akamine, Tsuyoshi Yoshitake, Chemical bonding of nitrogenated ultrananocrystalline diamond films deposited on titanium substrates by pulsed laser deposition, ECS Journal of Solid State Science and Technology, 10.1149/2.016311jss, 2, 11, M33-M38, 2013.08, [URL], Ultrananocrystalline diamond (UNCD)/nonhydrogenated nitrogenated amorphous carbon (a-C:N) composite (UNCD/a-C:N) films were prepared on titanium substrates in a nitrogen atmosphere by pulsed laser deposition, and their adhesion to the titanium substrates was remarkably improved as compared with those of UNCD/hydrogenated nitrogenized amorphous carbon (a-C:H:N) composite films deposited in a nitrogen and hydrogen mixture atmosphere. Their chemical bonding structures were investigated in details by X-ray photoemission and near edge X-ray absorption fine structure spectroscopies with synchrotron radiation. The UNCD/a-C:N films exhibit an obviously enhanced formation of sp2 and sp bonding such as C=N and CßN bonds. It should be contributable to the adhesion improvement. Since its formation locally disconnects sp3 bonding networks in the films, an internal stress, which is the main reason for exfoliation, should be released..
33.	K. Morimoto, N. Katayama, H. Akamine, M. Itakura, Coercivity enhancement of anisotropic Dy-free Nd-Fe-B powders by conventional HDDR process, Journal of Magnetism and Magnetic Materials, 10.1016/j.jmmm.2012.06.003, 324, 22, 3723-3726, 2012.11, Coercivity enhancement of Dy-free Nd-Fe-Co-B-Ga-Zr powders was studied using the conventional hydrogenation-decomposition-desorption-recombination (HDDR) process. It was found that the addition of Al together with the proper Nd content and the slow hydrogen desorption of the HDDR treatment can induce high coercivity in the powder. For example, the 14.0 at% Nd-2.0 at% Al powder exhibits H cJ of 1560 kA/m, B r of 1.22 T, and (BH) max of 257 kJ/m 3. The high coercivity inducement of the powder is thought to be attributed to the formation of Nd-rich phase, which continuously surrounds fine Nd 2Fe 14B grains. © 2012 Elsevier B.V..

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