加藤 博之 (カトウ ヒロユキ)
工学研究院 機械・宇宙航空工学部門 機械材料システム | 准教授 |
Last Updated :2025/02/13
■研究者基本情報
プロフィール情報
- 1996-97 KU Leuven, Belgium
1998-2001 Univ. Washington, Seattle USA
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J-Global ID
■経歴
経歴
学歴
■研究活動情報
論文
- Nonlinear deflection analysis of helical spring in elastic–perfect plastic material: Application to the plastic extension of piano wire spring
Hiroyuki Kato, Hitoshi Suzuki
Mechanics of Materials, 160, 103971, 103971, Elsevier BV, 2021年09月, [査読有り], [筆頭著者]
英語, 研究論文(学術雑誌) - Four-point bending tests to reveal tension-compression flow stress asymmetry in NiTi shape memory alloy thin plate
H. Kato
Materials Science and Engineering: A, 755, 258, 266, Elsevier BV, 2019年05月, [査読有り], [筆頭著者]
研究論文(学術雑誌) - 衝撃力と慣性力が作用する一端回転支持はりの曲げ変形モデルによる木製硬式野球バットの打撃変形解析
加藤博之, 川上順悟
日本機械学会論文集, 85, 877, 19, 00169, Japan Society of Mechanical Engineers, 2019年, [査読有り], [筆頭著者]
日本語, 研究論文(学術雑誌) - Shape memory effect and superelasticity of textured NiTi alloy wire
Hiroyuki Kato, Syun Fukushima, Kazuaki Sasaki
Advanced Structured Materials, 73, 43, 50, Springer Verlag, 2017年, [査読有り], [招待有り]
英語, 論文集(書籍)内論文, Shape memory effect and superelasticity of 9% tensile strain are obtained in Ti-50.5at.%Ni textured polycrystalline wires. The strain is larger by 2% than that of the original wire. Electron backscattered diffraction is taken to study the <
111>
texture developed in the wire which is solution treated by annealing at 900 °C followed by quenching into water. The extended strain recovery occurs after cold drawing by dies and annealing at 500 °C for 1 h. - Four-point bending test of the Bauschinger effect in prestrained IF steel thin sheet
Hiroyuki Kato, Kazuaki Sasaki, T. Mori
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 642, 150, 156, ELSEVIER SCIENCE SA, 2015年08月, [査読有り]
英語, 研究論文(学術雑誌), The Bauschinger effect in a 1 mm thick sheet of interstitial free (IF) steel was examined by tensile testing (prestraining) and subsequent four-point bending. The effect was absent when the prestrain was below 4% and was present when the prestrain was above 4%. The Bauschinger effect parameter determined the elastic back stress which developed after prestraining. The occurrence of back stress coincided with the development of dislocation cell structures, observed with transmission electron microscopy. (C) 2015 Elsevier B.V. All rights reserved. - 結晶粒界三重線における弾性不適合の回位モデル (回位の有限要素モデルの応用)
細矢隆史, 加藤博之, 佐々木一彰
日本機械学会論文集, 81, 830, 15, 00317, The Japan Society of Mechanical Engineers, 2015年, [査読有り], [責任著者]
日本語, 研究論文(学術雑誌), We examined the stress concentration that would occur at grain boundary triple lines during deformation in two copper tricrystals with [011] tilt boundaries; one was a symmetrical tricrystal with respect to the loading axis and the other was an anti-symmetrical one. In principle, the finite element method can provide solutions with prescribed amount of precision for the anisotropic elasticity problem. It was shown that a close approximation was possible by means of a disclination model in elastically homogeneous material. This disclination model was numerically solved with the finite element method proposed in a previous paper (Hosoya, Kato, Sasaki, Trans. JSME, Vol.80, No.819 (2014 ). It was concluded that the disclination model is appropriate for estimating the stress concentration at the grain boundary triple lines in deformed polycrystals. - Four-point bending test of determining stress-strain curves asymmetric between tension and compression
加藤博之, 鳥取豊, 佐々木一彰
Experimental Mechanics, 54, 7, 1715, 1718, 2014年05月, [査読有り]
英語, 研究論文(学術雑誌) - Four-Point Bending Test of Determining Stress-Strain Curves Asymmetric between Tension and Compression
H. Kato, Y. Tottori, K. Sasaki
EXPERIMENTAL MECHANICS, 54, 3, 489, 492, SPRINGER, 2014年03月, [査読有り]
英語, 研究論文(学術雑誌), A method of determining both uniaxial tension and compression stress-strain curves from the result of a single four-point bending test was demonstrated. Stress-strain curves of magnesium showing tension-compression asymmetry due to twinning deformation and those of an S45C steel due to the Bauschinger effect were calculated. The Mayville-Finnie equation was modified slightly for this calculation. The calculation is sensitive to small change in the slope of bending curve, revealing an aspect of inverse problem. - Back Stress Work Hardening Confirmed by Bauschinger Effect in a TRIP Steel Using Bending Tests
Hiroyuki Kato, Richard Moat, Tsutomu Mori, Kazuaki Sasaki, Philip Withers
ISIJ INTERNATIONAL, 54, 7, 1715, 1718, IRON STEEL INST JAPAN KEIDANREN KAIKAN, 2014年, [査読有り]
英語, 研究論文(学術雑誌), Martensite formed in TRIP steels causes large work hardening. The expectation that this is due to the back stresses induced into the ferrite by the hard martensite was examined by the Bauschinger effect after room temperature tensile straining of a TRIP steel into which the martensite had been introduced by prior straining at -50 degrees C. Bending tests were employed to detect the Bauschinger effect. The tests showed that the compressive flow stress became much smaller than the tensile flow stress and confirmed the expectation. - 形状記憶合金複合はりのセルフモルフィング材料設計
安田洋平, 加藤博之, 佐々木一彰
材料, 62, 12, 779, 785, 2013年12月, [査読有り]
日本語, 研究論文(学術雑誌), As the candidate for self-morphing elements and structures, the bending of composite beams including shape memory alloy fibers or plate is examined in terms of simple beam theory. The constitutive relation describing the internal stress/strain arising from the shape memory effect of the fibers is the key point of this design
this study provides the method of dealing with the stress and strain as the initial strain or the initial stress on the basis of the experimental evidences in literatures. This simplified method has advantages in deriving the geometry and statistics of the composite beam in explicit forms useful for designing purposes. The limit of the deflection of the composite beam is determined by the yield strength of the matrix: steel, aluminum and epoxy are considered. © 2013 The Society of Materials Science, Japan. - Transformation-induced plasticity as the origin of serrated flow in an NiTi shape memory alloy
Hiroyuki Kato, Kazuaki Sasaki
International Journal of Plasticity, 50, 37, 48, 2013年11月, [査読有り]
英語, 研究論文(学術雑誌), Transformation-induced plasticity was observed in an NiTi shape memory alloy. It was found that the austenite phase of a solutionized 50.5at.% Ni-Ti alloy shows a serrated stress-strain curve in a narrow range of 311-328 K, just below the temperature at which the deformation mechanism of the austenite phase changes from that of stress-induced martensitic transformation in the low temperature ranges to slip at high temperatures (329 K). Microstructure observation and thermal analysis have concluded the simultaneous occurrence of the two deformation mechanisms in the serrated flow. The interaction between the martensitic transformation and slip was investigated. © 2013 Elsevier Ltd. All rights reserved. - Clausius-Duhem inequality description of superelasticity in Ni-Ti polycrystal as a dissipative process
Yohei Yasuda, Hiroyuki Kato, Kazuaki Sasaki
SCRIPTA MATERIALIA, 66, 11, 939, 942, PERGAMON-ELSEVIER SCIENCE LTD, 2012年06月, [査読有り]
英語, 研究論文(学術雑誌), Superelasticity in Ni-Ti polycrystal is examined in terms of the second law of thermodynamics. As a consequence of the law, both the phase equilibrium and the dissipation of mechanical energy during the stress-induced martensitic transformation have been formulated simultaneously by means of the Clausius-Duhem inequality. The flow stress of superelasticity has been derived as the function of temperature. The energy dissipated in the shape memory effect is briefly discussed. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. - Avoiding error of determining the martensite finish temperature due to thermal inertia in differential scanning calorimetry: model and experiment of Ni-Ti and Cu-Al-Ni shape memory alloys
Hiroyuki Kato, Kazuaki Sasaki
JOURNAL OF MATERIALS SCIENCE, 47, 3, 1399, 1410, SPRINGER, 2012年02月, [査読有り]
英語, 研究論文(学術雑誌), It is known that the thermal effect (thermal inertia) in differential scanning calorimetry causes significant error of measuring the martensite finish temperature (Mf) in shape memory alloy, while the start temperature (Ms) is virtually unaffected. This article shows that the error can be avoided by accounting for the thermal effect quantitatively by mathematical modeling, if the kinetics of the martensitic transformation is properly prescribed. In common with two representative shape memory alloys, Cu-Al-Ni and Ni-Ti alloys, exponential decay is appropriate for expressing the kinetics. The model analysis is extended to the two methods of extrapolation which aims at excluding the thermal effect from DSC data. One is the extrapolation of the cooling rate to zero, and the other is that of the mass of sample to zero. It is shown that both extrapolations construct a temperature between the Ms and Mf. Typically, the temperature is below the Ms by one-third of the interval between the two temperatures. - Thermodynamic assessment of the stabilization effect in deformed shape memory alloy martensite
Hiroyuki Kato, Yohei Yasuda, Kazuaki Sasaki
ACTA MATERIALIA, 59, 10, 3955, 3964, PERGAMON-ELSEVIER SCIENCE LTD, 2011年06月, [査読有り]
英語, 研究論文(学術雑誌), When a martensitic shape memory alloy is deformed, the reverse transformation occurs at higher temperature than that of undeformed martensite. This is a typical case of the stabilization effect of martensite that is commonly observed in shape memory alloys. Regarding previous results measured by electric resistance and/or dilatometoric methods in NiTi and CuAlNi shape memory alloys, this study has performed calorimetric measurement in these alloys in order to re-examine the stabilization effect in terms of thermodynamics. Experimental evidence for appreciable changes in the reverse transformation temperature due to variant change of the martensite is presented. The elastic energy stored in the deformed martensite and the irreversible energy dissipated during the reverse transformation are estimated from the transformation temperatures, the stress-strain curves of the martensite and the latent heat of transformation. The temperatures of the reverse martensitic transformation have been related to these energies in explicit form. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. - Martensitic transformation and microstructure of Ti-rich Ti–Ni as-atomized powders
Tokujiro Yamamoto, Hiroyuki Kato, Yoshihiro Murakami, Hisamichi Kimura
Acta Materialia, 56, 20, 5927, 5937, PERGAMON-ELSEVIER SCIENCE LTD, 2008年12月, [査読有り]
英語, 研究論文(学術雑誌), Martensitic transformation was investigated for Ti-rich Ti-Ni gas-atomized powders as a function of powder size. The large powders clearly exhibit multiple martensitic transformations on both cooling from austenite to martensite and vice versa. With increasing powder size, the minor martensitic transformation temperatures increase and the amount of heat accompanying the minor transformation also increases. However, the main martensitic transformation temperature is almost the same, irrespective of the powder size. Microstructures of the as-atomized powders were examined to clarify why the powders exhibit the multiple martensitic transformations. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. - OBSERVATION OF LUDERS' BAND DEFORMATION DURING SUPERELASTICITY IN NITI ALLOY POLYCRYSTALS
Hiroyuki Kato, Kazuaki Sasaki, T. Mori
SMST-2007: PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON SHAPE MEMORY AND SUPERELASTIC TECHNOLOGIES, 209, +, ASM INTERNATIONAL, 2008年, [査読有り]
英語, 研究論文(国際会議プロシーディングス) - SUPERELASTICITY IN MANGANESE COPPER ALLOY SINGLE CRYSTALS
Hiroyuki Kato, Kazuaki Sasaki
SMST-2007: PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON SHAPE MEMORY AND SUPERELASTIC TECHNOLOGIES, 675, 682, ASM INTERNATIONAL, 2008年, [査読有り]
英語, 研究論文(国際会議プロシーディングス) - Model calculation of 3D-phase transformation diagram of ferromagnetic shape memory alloys
YC Liang, H Kato, M Taya
MECHANICS OF MATERIALS, 38, 5-6, 564, 570, ELSEVIER SCIENCE BV, 2006年05月, [査読有り]
英語, 研究論文(学術雑誌), A stress-magnetic field-temperature phase diagram of polycrystalline Fe-30.5%Pd ferromagnetic shape memory alloy (FSMA) is constructed based on experimental results and a thermodynamic model. The 3D-phase transformation diagram provides a key performance map in guiding us which actuation mechanism is the best for a given FSMA. According to this 3D-phase transformation diagram, the magnetic field induced transformation is found to be insignificant, while the hybrid mechanism based on the stress-induced martensitic transformation induced by the magnetic field gradient is more attractive. The NiMnGa system is also examined. (c) 2005 Elsevier Ltd. All rights reserved. - A one-dimensional modelling of constrained shape memory effect
H Kato, N Inagaki, K Sasaki
ACTA MATERIALIA, 52, 11, 3375, 3382, PERGAMON-ELSEVIER SCIENCE LTD, 2004年06月, [査読有り]
英語, 研究論文(学術雑誌), Stress is built up in a shape memory alloy if the strain recovery due to shape memory effect is blocked. This study provides a one-dimensional model for the analysis of the constrained shape memory effect. The model describes how the stress stabilizes a martensile at a temperature above the Af temperature. The condition for the martensite and austenite to reach equilibrium at that temperature has been obtained in terms of the balance between the elastic strain energy and the chemical (Helmholtz) free energy of the two phases. The stress values predicted from the model have been compared with the experimental results of a nickel-titanium shape memory alloy. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. - Phenomenological model of variant change during magnetization of martensite
Hiroyuki Kato, Kazuaki Sasaki
Philosophical Magazine Letters, 84, 5, 283, 291, 2004年05月, [査読有り]
英語, 研究論文(学術雑誌), The present study deals with the straining of ferromagnetic martensite in a magnetizing field. A phenomenological model of the movement of the interface between martensitic variants is developed for calculation of the strength of the magnetic field required for a variant change. The effect of uniaxial stress on interface movement is also examined. The results are applied to the martensite phases of NiMnGa and FePd ferromagnetic shape-memory alloys. - 界面上の有限長の層状介在物と転位の相互干渉
品川晃徳, 佐々木一彰, 加藤博之
日本金属学会誌, 68, 3, 191, 197, Japan Institute of Metals (JIM), 2004年, [査読有り]
日本語, 研究論文(学術雑誌), Interaction of an edge dislocation with a lamellar inclusion, which has a finite length and is on the interface of a bimetallic medium, is analyzed by a finite element model of an edge dislocation considering initial strain. The force exerted on the dislocation due to the elastic interaction can be numerically obtained by calculating the reduction of the potential energy, firstly proposed by Peach-Koehler. The glide and climb components of the force are computed. Contour plots for these components are presented. It is shown that, for certain combinations of material constants, the dislocation has an equilibrium position near the inclusion. Moreover, the interaction is affected by the direction of the Burgers vector with respect to the interface. - Structural change and straining in Fe-Pd polycrystals by magnetic field
T Wada, YC Liang, H Kato, T Tagawa, M Taya, T Mori
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 361, 1-2, 75, 82, ELSEVIER SCIENCE SA, 2003年11月, [査読有り]
英語, 研究論文(学術雑誌), The effect of a magnetic field on martensite structures in Fe-30 and -30.5at.% Pd has been studied using optical and electron (TEM) microscopy. No appreciable change to the martensite structure is observed with optical microscopy when a magnetic field of similar to8 x 10(5) A m(-1) is applied to a sample in the fully martensite state. The fractions of elementary martensite units (Bain correspondence variants-BCVs), existing as alternately stacked twins in a martensite plate and observed by electron microscopy, remain almost the same whether a TEM foil is under practically no magnetic field or under a field of more than similar to8 x 10(5) A m(-1). Fe-Pd is more difficult to magnetically saturate in the martensite state than in the austenite state, even though the saturation magnetization is only slightly smaller in the former state. Hysteresis in a magnetization-magnetic field relationship is small. From these observations, it is concluded that the magnetization in the martensite state is mostly achieved by rotation of the magnetization vector, with hardly any contribution from the movement of magnetic domain walls. This is reasoned using the argument that the interfaces of BCVs offer large resistance to the movement of magnetic domain walls. (C) 2003 Published by Elsevier B.V. - Energetics of variant conversion in ferromagnetic shape memory alloys by external magnetic fields
A Steuwer, T Mori, H Kato, T Wada
JOURNAL OF APPLIED PHYSICS, 94, 4, 2761, 2763, AMER INST PHYSICS, 2003年08月, [査読有り]
英語, 研究論文(学術雑誌), Using energetics, we examine the occurrence of large strains, so-called giant magnetostriction, in ferromagnetic shape memory alloys by the application of an external magnetic field. It is claimed that these strains originate from the conversion of one martensite variant to another. In this article, we attempt to show that magnetic work cannot supply the work required for the conversion of martensite variants in most cases. It is also pointed out that the latter work dissipates, while most of the magnetic work is conserved, as indicated by almost hysteresis-free magnetization curves. Therefore, simple energy conservation arguments rule out the suggested variant conversion mechanism not only quantitatively, but also qualitatively. A possible explanation for the occurrence of large strains is offered. (C) 2003 American Institute of Physics. - Straining of magnetic shape memory martensite by uniform magnetic field
H Kato, K Sasaki
SCRIPTA MATERIALIA, 48, 1, 31, 35, PERGAMON-ELSEVIER SCIENCE LTD, 2003年01月, [査読有り]
英語, 研究論文(学術雑誌), Variant change in ferromagnetic martensite associated with the exchange of magnetic domains is examined. The critical strength of magnetic field above which the variant change occurs is estimated by comparing the driving force for exchanging domain walls with the frictional stress for exchanging variants. (C) 2003 Published by Elsevier Science Ltd. on behalf of Acta Materialia Inc. - Straining of a polycrystal of Fe-Pd with martensite structure by uniaxial loading
YC Liang, T Wada, H Kato, T Tagawa, M Taya, T Mori
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 338, 1-2, 89, 96, ELSEVIER SCIENCE SA, 2002年12月, [査読有り]
英語, 研究論文(学術雑誌), This paper proposes a method to calculate the uniaxial stress-strain relationship of polycrystalline Fe-Pd, which has a martensite structure produced by cooling. Strain is caused by changes in the fractions of the three Bain corresponding variants which form the martensite structure within each grain. Internal stress and elastic energy are accumulated as straining proceeds and are caused by differences of eigenstrain (transformation strain) between differently oriented grains. The stress and elastic energy are evaluated on the basis of micromechanics. The stress acting on a grain due to surrounding grains is calculated using a mean field method. In this procedure, an averaging method is introduced, by which the mean field of grains having the same tensile direction, but having random lateral directions, are written in a closed form. The averaging method facilitates computations. It is shown that tension and compression differ in the stress-strain relationship. (C) 2002 Elsevier B.V. All rights reserved. - Martensite structure in polycrystalline Fe-Pd
H Kato, T Wada, YC Liang, T Tagawa, M Taya, T Mori
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 332, 1-2, 134, 139, ELSEVIER SCIENCE SA, 2002年07月, [査読有り]
英語, 研究論文(学術雑誌), The martensite structure in polycrystalline Fe-Pd has been examined from a mechanics and a crystallographic point of view. The structure consists of dark and bright plates, parallel to {110}. which, under no stress. exist in an equal amount. A plate has a fine structure, in which a set of twin-related variants adjoining on {110} interfaces is stacked together. That is, the dark plate contains two twin-related variants as does the bright plate. One variant in the bright plate is the same as one in the dark. The others are twin-related. In total, a grain is covered by equal amounts of three variants when transformation is completed. Straining caused by uniaxial loading is evaluated. (C) 2002 Elsevier Science B.V. All rights reserved. - Stress-induced FCC/FCT phase transformation in Fe-Pd alloy
H Kato, YC Liang, M Taya
SCRIPTA MATERIALIA, 46, 6, 471, 475, PERGAMON-ELSEVIER SCIENCE LTD, 2002年03月, [査読有り]
英語, 研究論文(学術雑誌), We report stress-induced martensitic transformation in tensile loaded Fe-30.5 at.% Pd polycrystals, mainly using optical microscopy. Reverse transformation occurs during unloading. Thermodynamic relationships between applied stress, transformation strain and the latent heat of transformation are examined. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved. - Straining of NiMnGa by stress and magnetic fields
YC Liang, H Kato, M Taya, T Mori
SCRIPTA MATERIALIA, 45, 5, 569, 574, PERGAMON-ELSEVIER SCIENCE LTD, 2001年09月, [査読有り]
英語, 研究論文(学術雑誌), This paper shows that martensitic transformation in Ni2MnGa strongly depends on stress but is insensitive to magnetic field up to 10 kG. However, stress caused by the force due to inhomogeneous magnetic field affects transformation and can induce large straining. (C) 2001 Published by Elsevier Science Ltd. on behalf of Acta Materialia Inc. - Effect of grain boundaries on the superelastic deformation of CuAlMn shape-memory bicrystals
H Kato, S Miura
SHAPE MEMORY MATERIALS AND ITS APPLICATIONS, 394-3, 205, 208, TRANS TECH PUBLICATIONS LTD, 2001年, [査読有り]
英語, 研究論文(学術雑誌), Cu-Al-Mn shape memory alloy bicrystals were grown by the Bridgman method. All the component single crystals showed superelasticity at room temperature. Superelastic shape recovery in a bicrystal having large difference of crystallographic orientation in two grains was incomplete, and plastic strain was left after unloading. Configuration of martensite variants near grain boundaries was different from the matrix, and was examined in terms of the compatibility of transformation strain at the boundaries. - Infinitesimal approach to the crystallography of martensitic transformation: Application to Ni-Ti
YC Liang, H Kato, M Taya, T Mori
SCRIPTA MATERIALIA, 43, 6, 535, 540, PERGAMON-ELSEVIER SCIENCE LTD, 2000年08月, [査読有り]
英語, 研究論文(学術雑誌) - Cyclic stress-strain response of superelastic Cu-Al-Mn alloy single crystals
H Kato, T Ozu, S Hashimoto, S Miura
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 264, 1-2, 245, 253, ELSEVIER SCIENCE SA, 1999年05月, [査読有り]
英語, 研究論文(学術雑誌), Stress-strain response of cyclic superelastic deformation was examined in Cu-20at.%Al-10at.%Mn shape memory alloy single crystals. As the superelastic deformation was repeated, the critical stress for the onset of stress-induced transformation decreased at an almost constant rate to zero by a finite number of cycles N-c. By further cycles residual martensite was accumulated until all the stress-induced martensite was left after unloading. The decrease of the stress per cycle and the number N-c depended on the direction of applied stress, i.e. tension, compression and tension-compression, and also the crystal orientation. These N-c's can be related by a linear S-N curve; log N-c decreased linearly with increasing log Delta sigma, where Delta sigma is the hysteresis-width in superelastic stress-strain curve. The observed fatigue behaviour can be understood in terms of internal stress of dislocation substructure formed during the cycles. (C) 1999 Elsevier Science S.A. All rights reserved. - High-temperature plasticity of the beta-phase in nearly-equiatomic nickel-titanium alloys
H Kato, T Yamamoto, S Hashimoto, S Miura
MATERIALS TRANSACTIONS JIM, 40, 4, 343, 350, JAPAN INST METALS, 1999年04月, [査読有り]
英語, 研究論文(学術雑誌), Plastic behaviour of the beta nickel-titanium alloys with nearly-equiatomic compositions, Ti-49.5, 50.0 and 50.5 mol%Ni, has been studied. The alloys were highly ductile due to dislocation glide at temperatures where the beta-phase was in equilibrium. The ductility became largest at the lowest temperature in the stability range of the beta-phase. The strain-rate vs. flow stress relations of easy-glide deformation in tensile testing and steady-state creep deformation satisfied the power law. Both of the deformations are associated with the dislocation glide which are likely to be controlled by the Peierls mechanism. A yield drop at the onset of plastic flow appeared only in the tensile deformation of Ti-50.5 mol%Ni, but not in Ti-49.5 and 50.0 mol%Ni alloys. Excess nickel atoms would exist as antistructure defects, which might be responsible for the yield point phenomena. - Two-way shape memory effect induced by tension training in Cu-13.4Al-4.0Ni (mass%) alloy single crystals
H Kato, R Stalmans, J Van Humbeeck
MATERIALS TRANSACTIONS JIM, 39, 3, 378, 386, JAPAN INST METALS, 1998年03月, [査読有り]
英語, 研究論文(学術雑誌), The two-way shape memory effect in CuAlNi shape memory alloy single crystals was studied. The effect was induced by cyclic tensile deformations of superelasticity and shape memory effect, and the efficiency of both methods was examined. Compared with the similar training process in the single crystals of CuZnAl alloys, the CuAlNi alloy showed much smaller changes in stress-strain behaviour and in the resulted two-way memory strain. The superelasticity training had no influence on both the stress-strain behaviour and the dilatation change. By shape memory training, the two-way memory strain increased to saturate at 0.90% after 10 cycles. Associated with this change, particular martensite variants increased its fraction and became "reproductive". However, they were not the variants that were induced during the training, and further increase in the two-way memory strain was impossible by the formation of the observed variants. It was concluded that the present training methods were not effective for the two-way memory effect in CuAlNi shape memory alloy. - Structure changes during pseudoelastic deformation of CuAlMn single crystals
J Dutkiewicz, H Kato, S Miura, U Messerschmidt, M Bartsch
ACTA MATERIALIA, 44, 11, 4597, 4609, PERGAMON-ELSEVIER SCIENCE LTD, 1996年11月, [査読有り]
英語, 研究論文(学術雑誌), Structure changes during pseudoelastic deformation of CuAlMn single crystals were investigated using in situ optical and high-voltage electron microscopy (HVEM). Several crystal orientations were investigated, from an irrational to [100] and [110] tensile axis and plane orientations in the case of thin foils. The composition of the alloy was chosen such as to obtain superelastic behavior at room temperature. Optical microstructures allowed to identify parallel plates at the beginning of the stress plateau, the number of which increased with strain. The stress/temperature phase diagram was established within the range of existence of gamma'(1) and beta'(1). During in situ HVEM deformation in the [100] direction of gamma'(1) plates nucleated on pre-existing ones. At later deformation stages 18R martensite was formed in stacks of narrow needles. The Following crystallographic relationship was observed: [001]beta(1) parallel to[010]beta'(1), gamma'(1) and [110]beta(1) parallel to[001]beta'(1), gamma'(1). A small permanent deformaticn observed after stress release was connected with the presence of residual martensite of a high random stacking fault density and consisting often of alpha'(1), gamma'(1) and beta'(1) martensite layers. During deformation in the (110) direction a larger permanent deformation and a density of dislocations was observed. Copyright (C) 1996 Acta Metallurgica Inc. - CRYSTAL ORIENTATION AND YIELD STRENGTH OF PURE MAGNESIUM CONTINUOUSLY CAST WITH A HEATED MOLD
S ONAKA, H KATO, S HASHIMOTO, S MIURA
JOURNAL OF THE JAPAN INSTITUTE OF METALS, 59, 6, 607, 611, JAPAN INST METALS, 1995年06月, [査読有り]
日本語, 研究論文(学術雑誌), Crystal orientation and yield strength are studied for a magnesium ingot continuously cast by the OCC process. The ingot consists of elongated subgrains parallel to the solidification direction. The disorientation angles between neighboring subgrains are about 2 degrees. Overall orientations of the subgrains in the ingot are well aligned and the ingot has a monocrystal-like structure. Anisotropy of plastic deformation is observed for specimens cut from the ingot, which is similar to that in magnesium monocrystals. It is found that the presence of subboundaries increases the critical resolved shear stresses for the basal-slip system. - Thermodynamical Analysis of Pseudoelasticity and Calorimetry in Shape Memory Alloys
Sei Miura, Hiroyuki Kato
Materials Science Research International, 1, 2, 67, 77, 1995年04月, [査読有り]
研究論文(学術雑誌) - Microstructural aspects of the fcc -fct. transformation during deformation in γ-Mn Cu alloy single crystals
加藤博之, 三浦
Philosophical Magazine. A., 71, 4, 781, 803, TAYLOR & FRANCIS LTD LONDON, 1995年04月, [査読有り]
英語, 研究論文(学術雑誌), The thermoelastic martensitic transformation and the stress-strain behaviour associated with the transformation in manganese-rich Mn-Cu alloys have been examined by tensile testing using single crystals grown by the Bridgman method. In the case of the deformation below the martensitic transformation temperature, twinning deformation in f.c.t. martensite has preceded dislocation glide, and the strain due to twinning showed a shape-memory effect. Regarding the continuous lattice parameter change, which can be observed in the temperature region extending over 100 K below the transformation temperature, the twinning strain decreased gradually by increasing the deformation temperature. It is shown that the shape-memory strain can be estimated by assuming the configuration of the twin-related domains of the f.c.t, martensite. Just above the transformation temperature, a stress-induced transformation has been found in the tensile testing. The characteristics of the stress-induced transformation from cubic to tetragonal structure in this alloy is discussed. - PSEUDOELASTIC DEFORMATION OF CUALMN SINGLE-CRYSTALS
J DUTKIEWICZ, M BARTSCH, S MIURA, U MESSERSCHMIDT, H KATO
JOURNAL DE PHYSIQUE IV, 5, C2, 275, 280, EDITIONS PHYSIQUE, 1995年02月, [査読有り]
英語, 研究論文(学術雑誌), Martensitic transformation associated with a tensile deformation of CuAlMn single crystals in [100] direction was studied using in-situ transmission electron microscopy. Stress/strain curves obtained during pseudoelastic deformation of microscopic samples were slightly different from bulk ones due to martensite formation in the stage of stress increase and a permanent deformation during the first cycle. Individual needles of 2H martensite were formed already in the early deformation stage. They were growing during stress increase, joining together into large plates. At later deformation stages 18R martensite was formed usuary in stacks of single plates. Following crystallographic relationship between parent and martensitic phases was observed: [001]beta(1) parallel to[010]gamma',beta' and [110]beta(1) parallel to[001]gamma',beta'. At a high stress concentration near crack tips, alpha' martensite of 3R lattice was observed. identification of martensite structure was very often not possible there, due to an extremely high random stacking faults density. - EFFECTS OF AGING ON PSEUDOELASTIC BEHAVIOR IN CU-15.0AT-PERCENT-SN ALLOY SINGLE-CRYSTALS
H KATO, N HIRATA, S MIURA
ACTA METALLURGICA ET MATERIALIA, 43, 1, 361, 369, PERGAMON-ELSEVIER SCIENCE LTD, 1995年01月, [査読有り]
英語, 研究論文(学術雑誌), The effect of aging on pseudoelasticity in a shape memory alloy was studied using single crystals of a CuSn alloy, in which the martensitic transformation behaviour is fairly susceptible to an aging treatment. The aging effect on the nucleation of martensite was investigated in the specimens aged in the parent phase. The effect on the growth of martensite was studied by strain aging during tensile testing, and also by the analysis of strain rate dependence of pseudoelasticity. The former effect is attributed to the embryo exhaustion due to the diffusion of Sn atoms, originally proposed by Kennon. On the other hand the latter is explained from the pinning of a martensite/parent interface by the diffusion of Sn atoms. - THERMODYNAMICAL ANALYSIS OF THE STRESS-INDUCED MARTENSITIC-TRANSFORMATION IN CU-15.0 AT-PERCENT SN ALLOY SINGLE-CRYSTALS
H KATO, S MIURA
ACTA METALLURGICA ET MATERIALIA, 43, 1, 351, 360, PERGAMON-ELSEVIER SCIENCE LTD, 1995年01月, [査読有り]
英語, 研究論文(学術雑誌), The stress-strain behavior associated with the martensitic transformation in the Cu-15.0 at.% Sn alloy has been examined thermodynamically. Tensile tests using single crystals showed that the successive martensite-to-martensite transformation can be induced under the applied tensile stress and is observed as a multi-stage stress-strain curve. The entropy change and the latent heat of stress-induced martensitic transformation were estimated from the calculation taking the dissipative energy of transformation into account. It will be shown that the dissipative energy contributes the decrease in the heat of the forward martensitic transformation and the increase in that of the reverse transformation. The calculated value is in good agreement with that measured by the differential scanning calorimeter. The dependence of the critical stress to induce martensite on the orientation of tensile axis has been examined, and it can be successfully explained by the orientation dependence of the mechanical driving force by the applied stress. - SUPERELASTICITY AND SHAPE-MEMORY EFFECT IN CU-23AT-PERCENT-AL-7AT-PERCENT-MN ALLOY SINGLE-CRYSTALS
H KATO, J DUTKIEWICZ, S MIURA
ACTA METALLURGICA ET MATERIALIA, 42, 4, 1359, 1365, PERGAMON-ELSEVIER SCIENCE LTD, 1994年04月, [査読有り]
英語, 研究論文(学術雑誌), Stress-strain behavior associated with the thermoelastic martensitic transformation in Cu-23at.%Al-7at.%Mn is studied using single crystals oriented the [001] direction. Shape memory effect and superelasticity are observed at a certain temperature range, and the multi-stage stress-strain curve due to successive stress-induced transformation has been found. This mechanical behavior is essentially identical to those of a Cu-Al-Ni alloy. However, owing to large dissipative force for the parent to gamma1', transformation, the stress-induced transformation which differs from that expected from the equilibrium phase diagram is observed. This results in an intermediate stress-strain behavior which has not been observed in the Cu-Al-Ni alloy. - STRESS-STRAIN BEHAVIOR AND SHAPE-MEMORY EFFECT IN POWDER-METALLURGY TINI ALLOYS
H KATO, T KOYARI, M TOKIZANE, S MIURA
ACTA METALLURGICA ET MATERIALIA, 42, 4, 1351, 1358, PERGAMON-ELSEVIER SCIENCE LTD, 1994年04月, [査読有り]
英語, 研究論文(学術雑誌), The shape memory properties of the TiNi alloy produced by a powder metallurgical method have been evaluated from tensile stress-strain curves. The contamination of the powders during atomization can be suppressed by applying the Plasma Rotating Electrode Process (P-REP), so that the compact made by Hot Isostatic Pressing (HIP) is expected to exhibit the shape memory effect identical to the typical alloy grown from melt. The fracture behavior of the P/M alloy is also studied, and the improvement of fracture strength of the P/M alloy is attempted. - SHAPE MEMORY AND SUPERELASTICITY IN POWDER METALLURGY TINI ALLOYS
S MIURA, H KATO, T KOYARI, K ISONISHI, M TOKIZANE
PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON MARTENSITIC TRANSFORMATIONS (ICOMAT-92), 887, 892, MONTEREY INST ADVANCED STUDIES, 1993年, [査読有り]
英語, 研究論文(国際会議プロシーディングス) - SHAPE MEMORY AND MECHANICAL-PROPERTIES IN POWDER-METALLURGY TINI ALLOYS
S MIURA, H KATO, T KOYARI, K ISONISHI, M TOKIZANE
MECHANICAL BEHAVIOUR OF MATERIALS-VI, VOLS 1-4, C223, C230, PERGAMON PRESS LTD, 1992年, [査読有り]
英語, 研究論文(国際会議プロシーディングス) - SHAPE MEMORY CHARACTERISTICS IN POWDER-METALLURGY TINI ALLOYS
H KATO, T KOYARI, S MIURA, K ISONISHI, M TOKIZANE
SCRIPTA METALLURGICA ET MATERIALIA, 24, 12, 2335, 2340, PERGAMON-ELSEVIER SCIENCE LTD, 1990年12月, [査読有り]
英語, 研究論文(学術雑誌)
その他活動・業績
- 道産ダケカンバの野球バットへの利用-硬式球衝突実験による衝撃変形特性の調査から
加藤博之, 秋津裕志, グリーンテクノ情報, 17, 2, 8, 12, 2021年09月
記事・総説・解説・論説等(その他) - 508 純アルミニウムのJ_
試験におけるき裂進展挙動に及ぼすサイドグループの影響(計算力学・材料力学II)
江川 博章, 加藤 博之, 佐々木 一彰, 北海道支部講演会講演概要集, 2010, 49, 125, 126, 2010年11月07日
一般社団法人日本機械学会, 日本語 - 507 応力誘起マルテンサイト変態におけるフェイスフィールドモデル(計算力学・材料力学II)
浅田 尚志, 加藤 博之, 佐々木 一彰, 北海道支部講演会講演概要集, 2010, 49, 123, 124, 2010年11月07日
一般社団法人日本機械学会, 日本語 - 415 形状記憶合金の超弾性と電気抵抗変化(材料力学III)
瀬尾 和也, 加藤 博之, 佐々木 一彰, 北海道支部講演会講演概要集, 2009, 48, 135, 136, 2009年11月28日
一般社団法人日本機械学会, 日本語 - 607 ニチノール形状記憶合金極細線の応力ひずみ挙動(機械材料とシミュレーションII)
木全 誠, 加藤 博之, 佐々木 一彰, 北海道支部講演会講演概要集, 2009, 48, 189, 190, 2009年11月28日
一般社団法人日本機械学会, 日本語 - OS1004 NiTi形状記憶合金の形状回復温度と予ひずみの関係(OS10-01 形状記憶材料の特性と応用1,OS10 形状記憶材料の特性と応用)
安田 洋平, 加藤 博之, 佐々木 一彰, M&M材料力学カンファレンス, 2008, "OS1004, 1"-"OS1004-2", 2008年09月16日
ニッケル・チタニウム形状記憶合金の線材を用いて、形状記憶効果により完全に回復する程度の予ひずみを与えた試験片において、予ひずみが形状回復温度に及ぼす効果を検討した。マルテンサイト変態の変態温度は、電気抵抗試験と熱膨張試験により測定した。両者の結果より,形状回復ひずみ範囲内の予ひずみを与えた場合でも、逆変態温度は数度上昇することを観察した。また、予ひずみが大きい程、変態ヒステレシスが小さくなり、逆変態による試験片の形状と電気抵抗値の変化が狭い温度域でシャープに起こるようになることを確認した。, 一般社団法人日本機械学会, 日本語
書籍等出版物
- Shape Memory and Superelasticity in Powder Metallurgy TiNi Alloys
Proceedings of ICOMAT-92, 1992年 - Pseudoelasticity and Shape Memory Effect in Mn- 18. 6at. % Cu Alloy Single Crystal
Proceedings of ICOMAT-92, 1992年 - Shape Memory and Mechanical Properties in Powder Metallurgy TiNi Alloys
Mechanical Behaviour of Materials. Pergamon, 1991年 - Superelasticity, Shapememory and Aging Effects in Cu-15at. % Sn alloy Single Crystals
Proc. MRAS Int'l. Mtg. on Adv. Mats., 1989年
講演・口頭発表等
- 形状記憶合金コイルばねの大変形解析
鈴木和, 加藤博之
日本機械学会北海道支部第56回講演会, 2018年10月13日, 日本語, 口頭発表(一般)
[国内会議] - NiTi形状記憶合金の超弾性機能疲労特性と形状記憶処理の関係
木内智之, 加藤博之
日本機械学会北海道支部第56回講演会, 2018年10月13日, 日本語, 口頭発表(一般)
[国内会議] - すべり変形したアルミニウム多結晶における微小荷重圧子押し込み試験
中谷友哉, 加藤博之
日本機械学会北海道支部第56回講演会, 2018年10月13日, 日本語, 口頭発表(一般)
[国内会議] - NiTi形状記憶合金繊維/アルミニウム複合材料の相変化潜熱蓄熱効果
浅野謙進, 加藤博之
日本機械学会北海道支部第56回講演会, 2018年10月13日, 日本語, 口頭発表(一般)
[国内会議] - 木製硬式野球用バットの衝撃変形特性
川上順悟, 加藤博之
日本機械学会北海道支部第56回講演会, 2018年10月13日, 日本語, 口頭発表(一般)
[国内会議] - 引っ張り/圧縮荷重下のアルミニウム板状試料における微小荷重押し込み試験
清水友太, 加藤博之
JSME Hokkaido, 2018年10月13日, 日本語, 口頭発表(一般)
[国内会議] - 触診センサーを目指した剛体球の軟物質押し込み変形解析
若竹浩志, 加藤博之
日本機械学会北海道支部第56回講演会, 2018年10月13日, 日本語, 口頭発表(一般)
[国内会議] - 離散要素法による剛体粒子集合体の接触点すべり解析
久々津諒平, 加藤博之
日本機械学会北海道支部第56回講演会, 2018年10月13日, 日本語, 口頭発表(一般)
[国内会議] - 回位の弾性特異応力場とひずみエネルギーの試料寸法依存性
加藤博之, 鳥井俊作
第3回マルチスケール材料力学シンポジウム, 2018年05月25日, 日本語, 口頭発表(一般)
[国内会議] - 形状記憶合金の熱弾性型マルテンサイト変態における変態潜熱量
加藤博之, 浅野謙進
日本金属学会H30春期大会講演会, 2018年03月21日, 日本語, 口頭発表(一般)
[国内会議]
共同研究・競争的資金等の研究課題
- 熱弾性型マルテンサイト変態における潜熱の非定常伝達と蓄熱効果
科学研究費助成事業
2019年04月01日 - 2024年03月31日
加藤 博之
4種類の形状記憶合金,ニッケルチタン(NiTi),鉄パラジウム(FePd),マンガン銅(MnCu),銅・アルミニウム・マンガン(CuAlMn)のマルテンサイト変態を光学顕微鏡により観察した。DSCで測定した潜熱は大きく異なった(MnCuそれぞれ,高温のオーステナイト相の試料の表面を機械研磨および電解研磨で平滑にして,冷却によってマルテンサイト変態を起こし,その表面起伏による光学的なコントラストを観察した。また、市販のサーマルカメラにより表面の温度分布を計測した。NiTi合金では潜熱の排熱で局所的に10Kまで上昇することを確認した。
NiTi合金の動脈カテーテルは通電加熱により開口の動作をするが,この動作を形状記憶合金ばねの伸縮で模擬した。NiTiばねを自作して通電加熱による形状記憶動作を観察し,弾塑性力学によるモデル化を試みた。形状記憶合金のばねを考える前に,定式化の一般論を公開する必要があり,ピアノ線のばねについて非線形理論を論文で公開した。
フェイズフィールド法による相変態の非平衡緩和過程の計算と潜熱の伝熱方程式を連立させて一次元問題の解を得た。この解は単一平面のマルテンサイト/母相界面の伝達を表現する。NiTi形状記憶合金の超弾性について,フェイズフィールドによる界面速度の計算を行い,実測値と比較した結果を論文としてまとめている。
形状記憶合金の潜熱蓄熱効果の応用例を三次元有限要素伝熱解析で示した。エンタルピー曲線を厳密に定義して入力することでANSYSで解析が可能となった。アルミニウムとNiTi合金ワイヤの複合材料を考案し,ファン空冷との併用を考えてパソコンのCPUのヒートシンクをモデルとし計算機実験で蓄熱効果を初めて示すことが出来た。
日本学術振興会, 基盤研究(C), 北海道大学, 19K04981 - 形状記憶素材を活用した軽量・低温強度を有する新規複合材料の開発
シーズ育成
2008年12月 - 2009年03月
加藤博之
JST, 研究代表者, 競争的資金 - 先進LSI銅配線薄膜の端部剥離強度評価法の開発
科学研究費助成事業
2001年 - 2002年
北村 隆行, 中村 友二, 梅野 宜崇, 加藤 博之
先進大規模集積回路(LSI)の配線には,電気抵抗の低減と原子マイグレーションによる破断防止のために銅が用いられている.銅配線を用いる場合には,基板への銅原子の拡散を防ぐために銅と基板の間にバリヤー層が配置されているが,.銅薄膜とバリヤー層は密着性が良くないため,端部からの剥離発生が問題となる.界面端部にはフリーエッジ効果によって応力が集中しており,これによって生ずる界面端はく離の力学的挙動を明らかにする必要があるが,これまで適切な端部剥離評価法がなかった.本研究では,破壊力学の概念を援用して,界面端部の亀裂発生試験法を考案し,力学的に正確な薄膜界面端部剥離強度評価法を開発した.剛性の高いはりによって薄膜の変形を強く拘束し,不要薄膜部分を切除することによって,薄膜の塑性変形や破壊が界面強度評価に影響を及ぼすことを防止するように工夫した試験片を用意した.この試験片に対して,ビッカース硬さ試験装置を改良した微小荷重負荷試験装置によって界面端部からの剥離試験を行い,境界要素法解析および分子動力学解析によって剥離を支配する力学量,すなわちフリーエッジ効果による応力拡大係数を評価できることを明らかにした.また,この方法によってシリコン基板上に形成したバリヤー膜(TiN)と銅薄膜の界面端からの亀裂発生強度を評価した.さらに,膜作成時に導入された内部応力を測定し,界面端剥離強度の膜厚依存性について検討した.その結果,内部応力と外部機械的負荷の重ね合わせによる端部応力が,亀裂発生の真の駆動力であることを見出した.
日本学術振興会, 基盤研究(B), 京都大学, 13555026 - 金属間化合物の中間温度および高温疲労挙動
奨励(A)
1998年04月 - 1999年03月
加藤 博之
JSPS, 研究代表者, 競争的資金 - 粉末焼結メゾ粒子ニチノール超弾性・彫塑生形状記憶合金の開発
科学研究費 試験B
1995年04月 - 1998年03月
加藤博之
JSPS, 研究代表者, 競争的資金 - 集合組織制御した微細粒二相ステンレス鋼板の超塑性
科学研究費助成事業
1998年 - 1998年
橋本 敏, 宮本 博之, 加藤 博之, 御牧 拓郎
二相ステンレス鋼は微細粒超塑性を示す代表的な金属材料であり、一般的に微細粒超塑性においては粒界すべりおよび相界面すべりが支配的な機構であることが知られている。著者らはγ(FCC)/α(BCC)ステンレス鋼異相双結晶等を用いたクリープ試験からγ/α相界面は本質的に単相粒界に比べてすべり易いことを明らかにした[1,2]。一方、単相の粒界すべりは方位関係の影響を受けることが純Zn、Al等について報告されていることから相界面すべりについてもγ相/α相の方位関係の影響を受けることが予想される。そこで本研究では異相間の方位関係分布の定性的指標となる各相の集合組織が二相ステンレス鋼板の超塑性変形挙動に及ぼす影響を明らかにすることを目的とする。本年度は第一段階として他に報告されているα(FCC)/β(BCC)Brass等の双結晶クリープの実験データも加えてFCC/BCC相界面すべり機構の理論的検討を行い[3]、さらに相界面と単相粒界における本質的なすべり易さの違いを含めた二相(FCC/BCC)鋼の変形機構を提案し[4]、これまで報告されてきた実験データにより検証をおこなった。
双結晶を用いたクリープ試験から、変形抵抗が異なるFCC相およびBCC相から構成される相界面と単相粒界におけるすべり抵抗の顕著な差異が明らかとなった。この知見より超塑性変形における相界面の役割として、相界面すべりにより超塑性ひずみの大部分を請け負う変形モデルを提案した。これは第二相が変形中に粒成長を抑制し微細組織を安定化するという従来の役割とは異なる視点から変形機構を示唆するものである。
日本学術振興会, 特定領域研究(A), 京都大学, 10122209 - 三重結晶の変形,破壊挙動に基づいた粒界設計に関する研究
科学研究費 一般(A)
1994年04月 - 1996年03月
三浦精
JSPS, 競争的資金 - 粒界上に液相粒子を含むバイおよびトライ・クリスタルの高温変形挙動
科学研究費助成事業
1996年 - 1996年
尾中 晋, 加藤 博之, 橋本 敏
多結晶中の液相粒子が大きな量の粒界すべりを起こすための付随調整機構として重要であるという指摘がなされているが,液相粒子が結晶の塑性変形に及ぼす影響や粒界上の液相粒子が粒界でのすべりや破壊におよぼす影響には不明の点が数多く存在する.そこで本研究では液相粒子を含む銅単結晶,銅双結晶(バイクリスタル)そして銅多結晶についての実験的,理論的検討を行ない,結晶粒内や結晶粒界上の液相粒子が結晶の塑性変形や結晶粒界のすべりにおよぼす影響について多方向からの考察をした.また,粒界上に液相粒子を含む三重結晶(トライクリスタル)の高温変形挙動を調査する準備として,銅基固溶体合金三重結晶の高温変形挙動におよぼす粒界三重点の影響についても考察を加えた.得られた結果をまとめると以下のようになる.
1.B_2O_3粒子が銅母相単結晶の高温変形挙動に及ぼす影響
(1)液相B_2O_3粒子は,固相SiO_2粒子と同じく母相の高温強化に有効である.
(2)固相SiO_2粒子は,液相B_2O_3粒子と同じく高温域では材料に加工硬化をもたらす原因とはならない.
2.粒界上のB_2O_3粒子が銅多結晶と双結晶の高温変形挙動に及ぼす影響
(1)粒界上の液相B_2O_3粒子は,銅多結晶の脆性的な粒界破壊の原因になる.
(2)粒界上の液相B_2O_3粒子は,粒界上の固相GeO_2粒子に比較して銅多結晶の粒界破壊をより促進する.
3.粒界三重線が三重結合の粒界破壊におよぼす影響.
三重線は中間的な温度域では粒界破壊を抑制するものの,高温域では粒界き裂の優先発生箇所になる.
日本学術振興会, 重点領域研究, 京都大学, 08242215 - TiNi形状記憶合金の高温変形
科学研究費 奨励(A)
1993年04月 - 1994年03月
加藤博之
JSPS, 研究代表者, 競争的資金 - CuAlMn形状記憶合金単結晶の超弾性と形状記憶効果
科学研究費 奨励(A)
1992年04月 - 1993年03月
加藤博之
JSPS, 研究代表者, 競争的資金 - オーステナイト・フェライト二相ステンレス鋼双結晶の界面構造と機械的性質
科学研究費助成事業
1993年 - 1993年
橋本 敏, 加藤 博之, 尾中 晋, 三浦 精
Fe-15Cr-15Ni(オーステナイト(γ)ステンレス鋼)およびFe-30Cr(フェライト(α)ステンレス鋼)単結晶から二相(γ/α)ステンレス鋼双結晶と各相の双結晶を拡散接合により作製して、その機械的性質を高温および室温で調査した結果、次のことが明らかとなった。
1.1373K、アルゴン雰囲気中で、界面に平行にSimple shear実験(初期せん断応力、τ=1.0MPa)を行なった結果、γ/α相界面のすべり速度vは約5×10^<-6>ms^<-1>であり、α、γ相の粒界すべり速度に比べて約10^2〜10^3速いことが判明した。相界面のすべり速度の応力感受性指数nはn=2となり、vα/γ=const.τ^2が実験的に求められ、これは二相ステンレス鋼の超塑性領域のn値と一致する。すべり変形後の界面の様相から相界面すべりは界面自体のすべりではなく極く近傍のsofterなα相側での粘性的な物質の流動によることが明らかとなり、harderなγ相に運動を阻止されたα相内の転位の上昇とすべり運動の繰返しによるものと結論した。以上の結果をもとにsoftとhardの相からなる二相合金多結晶の超塑性変形モデルとその構成式を提案し、従来報告されている観測結果をよく説明することを報告した。
2.種々の方位関係と界面方位を有する二相双結晶を界面と平行に室温で塑性変形し、界面での変形挙動をすべり線観察より論じた。弾性および塑性の歪の不適合性の大小、不適合性による応力の発生から界面での付加的すべりの挙動を説明できた。
日本学術振興会, 一般研究(C), 京都大学, 05650618 - Plastic deformation of intermetallic compounds
競争的資金 - Stress-strain behavior during plastic deformation of metals stress-strain behavior
競争的資金 - Stress-strain behavior of shape memory allos
競争的資金