JaLCDOI 10.18926/19648
FullText URL Mem_Fac_Eng_OU_33_2_1.pdf
Author Omura, Yasuhiro| Hida, Moritaka| Sakakibara, Akira| Takemoto, Yoshito|
Abstract Molecular dynamics simulation of nickel crystal under uniaxial tensile and compressive deformation was performed for single nenocrystal model and twinned nanocrystal model composed of 1550 atoms using EAM (embedded atom method) potential with the object of investigating deformation induced phase tranformation (especially twin deformation). In the case of single nanocrystal model, the evolution and development of twin deformation, (111)[11(2)], is observed under compressive loading in [001] direction, whereas either slip or twin deformation is not recognized under tensile loading. In the case of twinned nanocrystal model, twin, (111)[11(2)], decreases and disappears under tensile loading, and develops under compressive loading, It is suggested from the difference of results between single nanocrystal model and twinned nanocrystal model that it is easy for twin to induce local deformation.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1999-04-27
Volume volume33
Issue issue2
Start Page 1
End Page 8
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309020
JaLCDOI 10.18926/19619
FullText URL Mem_Fac_Eng_OU_31_1_1.pdf
Author Sakakibara, Akira| Nakagawa, Keiyu| Hosokawa, Norio| Kanadani, Teruto|
Abstract Dependence of precipitation hardening on the distance from specimen surface and effect of the surface layer on the fatigue strength of an Al-1.2mass% Si alloy were studied by microhardness test, transmission electron microscopy and repeated tension fatigue test. Rate of age-hardening was slower in the vicinity of surface than in the interior of the specimen aged at 423K after quenching from 853K. The result of the electron microscopy was that the size ot Si precipitates formed in the vicinity of surface was smaller than in the interior of specimen aged for 6ks at 423K. This difference was considered to be caused by the effect of the surface as vacancy sinks which slowed down the growh of Si precipitates in the vicinity of the specimen surface. A specimen surface layer whose hardness was different from that of the specimen interior was formed at the vicinity of the surface when the specimen was aged at relatively low temperature such as 423K. The fatigue strength in repeated tensile test ot the specimen did not depend on whether the specimen surface layer was present or not.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1996-12-27
Volume volume31
Issue issue1
Start Page 1
End Page 3
ISSN 0475-0071
language 英語
File Version publisher
NAID 120005816788
JaLCDOI 10.18926/19604
FullText URL Mem_Fac_Eng_OU_33_1_1.pdf
Author Sakakibara, Akira| Kanadani, Teruto|
Abstract Aging of diolute Al-Ag alloys after quenching from low temperatures were studied mainly by electrical resistometry. Maximum resistivity observed in the aging curve of specimens quenched from high temeperature disappeared when the quenching temperature was lowered to 473 or 453K. When the quenching temperature was lowered further to 423K or lower, however, maximum resistivity reappeared. At the temperature lower than or equal to 423K but higher than the GP zone solvus, the alloys were not homogeneous but had clusters of solute atoms or fluctuation of solute concentration. Inhomogeneous distribution of solute atoms may affect the aging behavior after quenching from that temperature.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1998-11-30
Volume volume33
Issue issue1
Start Page 1
End Page 4
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309092
JaLCDOI 10.18926/15818
FullText URL Mem_Sch_Eng_OU_20_2_21.pdf
Author Yamada, Masuo| Ohta, Mutsuo| Sakakibara, Akira|
Abstract A series of small-angle X-ray scattering photographs with monochromated and point focussed copper Ka(1) radiation was taken of a single crystal of an Al-4mass % Cu alloy at the as-quenched state from 823K and at successive stages of ageing at 313K. The crystal was so oriented that the incident direction of the radiation was along [001] axis, and was cooled with liquid nitrogen during the exposure. The pattern of the as-quenched state was homogeneous, but each of the patterns of the aged states consisted of streaks along [100] and [010] directions and a quasi-ring around the trace of the incident beam on the film (even at the shortest ageing time. l6sec). The most intense regions were found in [100], [010] , [100] and [010] directions on the ring. With the progress of the ageing the streaks and the ring became more intense and narrower. The results can be interpreted from points of view of the formation of the GP zones parallel to {100} planes ab initio, the effect of the inter-particle interference on scattering of X-rays, and the growth of the GP zones with the ageing. Guinier radius of the GP zones at each stage can be obtained from intensity change along [110], and the values are reasonably consistent with those obtained from the cross section of the streak. The presence of multi-layer zones, besides the one-layer ones, is suggested from the humps found on several intensity curves along [100] at later stages.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1986-02-28
Volume volume20
Issue issue2
Start Page 21
End Page 33
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307538
JaLCDOI 10.18926/15808
FullText URL Mem_Sch_Eng_OU_20_1_35.pdf
Author Yamada, Masuo| Sakakibara, Akira| Ohta, Mutsuo|
Abstract Photographic method for measurement of small-angl X-ray scattering (SAXS) is improved. Intense pointfocussing incident beam is obtained by using doubly bent crystal monochromator made of aluminium single crystal. Microphotometry and the subsequent calculation to obtain profiles, Guinier and Porod radii, integrated intensities, and so on are facilitated by using microcomputer. Integrated SAXS intensities measured from an Al-Zn alloy which has been treated under the same heat treatment conditions are coincident with one another with probable errors less than ±6 % . Ratio of the integrated intensities obtained from two Al-Zn alloys of different composition is reasonable compared with the quasi-equilibrium phase diagram.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1985-11-08
Volume volume20
Issue issue1
Start Page 35
End Page 43
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307157
JaLCDOI 10.18926/15770
FullText URL Mem_Sch_Eng_OU_15_2_29.pdf
Author Ohta, Mutsuo| Kanadani, Teruto| Sakakibara, Akira| Yamada, Masuo|
Abstract Measurements of electrical resistivity and intensity of small-angle X-ray scattering and transmission electron microscopy were made on Al-Zn alloys of several compositions. G.P. zones are formed by the nucleation-and-growth mechanism above the spinodal temperature. The nucleus has a critical size for growth. This size becomes larger when aged at higher temperatures. The sizes of the G.P. zones formed by this mechanism distribute broadly, but those formed by the spinodal decomposition do closely. The spinodal temperatures estimated for Al-10.0, 12.5, 15.0, and 20.0wt % Zn alloys are ~95, ~110, ~130, and ~180℃, respectively. The critical temperatures below which G.P. zones are observed in these alloys are ~115, ~135, ~160, and ~210℃, respectively.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1981-03-30
Volume volume15
Issue issue2
Start Page 29
End Page 53
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307895
JaLCDOI 10.18926/15727
FullText URL Mem_Sch_Eng_OU_12_77.pdf
Author Ohta, Mutsuo| Kobayashi, Toshinori| Sakakibara, Akira|
Abstract The clustering phenomenon was observed when dilute Al-Zn alloys were annealed at temperatures higher than the solvus of the G.P.zones. In this report the apparent activation energy for clustering is estimated and compared with the experimental results. The estimated value of the apparent activation energy for clustering in several Al-Zn alloys comes to 0.51 eV, which is larger than the effective migration energy 0.43 eV of Zn atoms in Al-Zn alloys.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1978-02-25
Volume volume12
Start Page 77
End Page 88
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307178
JaLCDOI 10.18926/15725
FullText URL Mem_Sch_Eng_OU_12_59.pdf
Author Ohta, Mutsuo| Kanadani, Teruto| Sakakibara, Akira|
Abstract Several Al-Zn alloys containing 0.041-4.4 at % Zn were studied by means of measurements of electrical resistivity. The results obtained are as follows : (1) The electrical resistivity increases when the specimen is annealed at temperatures higher than the solvus temperature of the G.P. zones. The increase of the resistivity is due to the formation of fluctuation. (2) The electrical resistivity of the specimen containing fluctuation is dependent upon annealing temperature only and independent of quenching temperature. (3) The fluctuation is formed in very dilute alloys as 0.041 at % Zn at temperatures higher than the solvus temperature of the G.P. zones. (4) The formation energy of vacancy and the migration energy of the Zn atom in the alloys determined by the formation process of fluctuation are in good agreement with those by the formation process of G.P. zones. (5) In spite of the result (4), it seems that the fluctuation is not the same as the small G.P. zones which are observed in the early stage of aging.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1978-02-25
Volume volume12
Start Page 59
End Page 75
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307636
JaLCDOI 10.18926/15715
FullText URL Mem_Sch_Eng_OU_13_133.pdf
Author Ohta, Mutsuo| Kanadani, Teruto| Yamada, Masuo| Sakakibara, Akira|
Abstract Aging and reversion in dilute Al-Ag alloys are studied by means of the measurements of electrical resistivity. Results obtained are as follows: 1) Increase in the as-quenched resistivity is found for a low quenching temperature. This increase may be due to the fluctuation of solute concentration at the quenching temperature. 2) When the fluctuation exists in the alloy, the aging rate becomes slow and the maximum resistivity in the isothermal aging curve becomes small as the vacancyconcentration becomes low. The maximum resistivity becomes large again when the vacancy concentration becomes further lower, and finally the maximum does not appear. 3) These behaviors are explained in terms of the difference in the rate of growth of the G.P. zones in the regions of higher and lower solute concentration induced by the fluctuation and in terms of the change of this difference with vacancy concentration. 4) G.P. zones may be formed by the spinodal decomposition with indefinite surfaces at first, grown to larger ones with difinite surfaces and changed to ordered nzones in the alloy. 5) It is confirmed that G.P. zones are formed by the nucleation-and-growth mechanism also in Al-Ag alloys above the spinodal temperature.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1979-03-05
Volume volume13
Start Page 133
End Page 152
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307468
JaLCDOI 10.18926/15712
FullText URL Mem_Sch_Eng_OU_13_119.pdf
Author Ohta, Mutsuo| Yamada, Masuo| Kanadani, Teruto| Sakakibara, Akira|
Abstract The effects of the fluctuation of solute concentration on the process of aging in Al-10wt % Zn alloy were studied by measurements of the intensity of small-angle X-ray scattering and by electron microscopy. Specimen was quenched from a higher temperature(T(Ql), mainly 300℃) to an intermediate temperature (T(Q2), 110~230℃), held there for a time, quenched again into iced water and aged isothermally at 0℃ or 40℃. Results obtained are as follows: (1) When the specimen was held at T(Q2) for a sufficient time and aged at relatively high temperatue(e.g. Ihr at 125℃ and aged at 40℃), a two-step increasing of both resistivity and integrated intensity was found. (2) Each of the steps has characteristics of the formation of G.P. zones by the spinodal decomposition. (3) When the maximum resistivity(p(max)) takes a minimum, Size distribution of the G.P. zones, estimated from the difference between Guinier and Porod radii, is much broader than that at p(max) in the usual direct quenching. (4) When the holding time at T(Q2) is long enough, the size distribution at p(max) is as broad as that at p(max) in the usual case. (5) After a prolonged aging under the condition that P(max) takes minimum, G.P. zones grow markedly and become oblate ellipsoidal with a major axis of about 20nm. (6) These results are consistently understood in terms of the fluctuation of solute concentration at T(Q2) and the change in the concentration of vacancies during annealing at T(Q2). That is, it is considered that these results are due to the difference in aging behavior between the regions of relatively high concentration and the ones of low concentration induced by the fluctuation.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1979-03-05
Volume volume13
Start Page 119
End Page 132
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307931
JaLCDOI 10.18926/15709
FullText URL Mem_Sch_Eng_OU_13_95.pdf
Author Ohta, Mutsuo| Kanadani, Teruto| Yamada, Masuo| Sakakibara, Akira|
Abstract Aging process in Al-Zn alloys was studied by the measurements of the electrical resistivity when the alloy was quenched from a high temperature, about 300℃ (the first quenching temperature), to an intermediate temperature, between 110℃ and 230℃ (the second quenching temperature), held at this temperature for a time, quenched again into iced water and aged at a low temperature. Variation of the holding time at the second quenching temperature brings about the variation of the isothermal aging curves. Maximum resistivity of the isothermal aging curve, p(max) , decreases at first, passes a minimum and then increases to reach a stationary value as the holding time at the intermediate temperature increases. It is pointed out that this phenomenon is mainly due to the fluctuation of solute concentration and the vacancy concentration decreasing at the intermediate temperature.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1979-03-05
Volume volume13
Start Page 95
End Page 117
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307526
JaLCDOI 10.18926/15693
FullText URL Mem_Sch_Eng_OU_10_2_81.pdf
Author Sakakibara, Akira|
Abstract To acquire information on the interaction between oxygen molecules in solid phase, studies have been carried out on the magnetic properties of solid oxygen, oxygen-argon and oxygen-fluorine. Review of the studies on the interaction between oxygen molecules is cited. Magnetic susceptibility was measured by the Faraday method as a function of temperature from 12 K to the melting point of them. Pure oxygen both in α and β phase indicates paramagnetism corresponding to long-range antiferromagnetic order. Oxygen -argon mixtures of 92~66 mol% oxygen content indicate large susceptibility corresponding to δ phase, which can be interpreted in terms of the cluster of oxygen molecules in trimer. Small paramagnetism was found for the oxygenfluorine mixture even as dilute as 10 mol% oxygen content, which may be due to the strong antiferromagnetic interaction. This can be interpreted in terms of super-exchange interaction between oxygen molecules via fluorine molecule.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1976-01-27
Volume volume10
Issue issue2
Start Page 81
End Page 111
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307359
JaLCDOI 10.18926/15679
FullText URL Mem_Sch_Eng_OU_10_1_49.pdf
Author Ohta, Mutsuo| Kawazoe, Hisami| Sakakibara, Akira|
Abstract Binding energy between a vacancy and a Zn atom in Al was investigated by measurement of as-quenched resistivity in Al-0.021at % Zn and pure-Al, with the estimation of vacancy loss during quenching. The contribution of clusters to resistivity in Al-0.021at % Zn waa also investigated. Their results are summarized as follows: (1) The results of isothermal and isochronal annealing indicate that clusters in Al-0.021at % Zn cnuld not be detected beyond the experimental errors. (2) The model applied to estimate the vacancy loss in pure-Al has enough validity. The quantitative estimation of clusters ana the improvement in experimental conditions are greatly desired, which enable the more detailed, analysis of the data.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1975-07-01
Volume volume10
Issue issue1
Start Page 49
End Page 59
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307807
JaLCDOI 10.18926/15506
FullText URL Mem_Fac_Eng_OU_25_2_17.pdf
Author Sakakibara, Akira| Kanadani, Teruto| Kaneeda, Toshiaki| Hosokawa, Norio|
Abstract Effect of the soft surface layer that was formed on low temperature aging of Al-Zn alloy on fatigue strength was studied under repeated tensile loading. Vickers microhardness test revealed that there existed less hardened region in the vicinity of grain boundary and surface, and that the region extends 50 to 100μm from the surface inward. From the plot of the stress amplitude against the number of cycles to failure, it is concluded that the presence of less hardened surface layer strengthens fatigue resistance of the age hardened Al-Zn alloys containing 8 to 16mass % Zn under the repeated tensile loading.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1991-03-28
Volume volume25
Issue issue2
Start Page 17
End Page 23
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307685
JaLCDOI 10.18926/15503
FullText URL Mem_Fac_Eng_OU_25_2_9.pdf
Author Mikuni, Masato| Hida, Moritaka| Nishida, Norihide| Sakakibara, Akira| Yamada, Masuo|
Abstract Strains induced in the Si substrates by TiN film were observed with X-ray topography. The image of the sample with TiN film 0.45μm thick was like that of a dislocation loop observed with transmission electron microscope. The images of the samples with TiN films 1.65, and 1.9μm thick were different; blackening spreaded in the <112> and <110> direction from the ring contrast in shape of four-lobed rosette pattern. Spreading extended 1.6 times longer than the radius of the ring contrast along the <112> direction. The strain field extended 0.1μm in depth from the top surface where TiN was plated. From the topographs of bent Si beam, it was found that the blackness was almost proportional to the strain. The strains induced by TiN film locally ion-plated were smaller than those observed previously when TiN was ion-plated on the whole top surface of the substrate. Fine structures were observed in the topographs which could not be explained by the kinematical theory.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1991-03-28
Volume volume25
Issue issue2
Start Page 9
End Page 15
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307429
JaLCDOI 10.18926/15500
FullText URL Mem_Fac_Eng_OU_25_2_1.pdf
Author Okada, Hiroyuki| Hida, Moritaka| Sakakibara, Akira| Takemoto, Yoshito|
Abstract Tensile strength and elongation of cast magnesium reinforced with titanium fiber were measured by tensile test. The pull-out test of a titanium rod partially embedded in a magnesium matrix was performed to evaluate interfacial bonding strength between magnesium and titanium. It was found that when the fiber volume fraction was changed from 1% to 14%, the tensile strength was improved with increase of volume fraction, while the improvement of elongation tended to be restrained beyond the volume fraction of 10%. The interfacial strength was revealed to be strong, and this was substantiated by the scanning electron microscopy showing an excellent wettability between the titanium fiber and the magnesium matrix.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1991-03-28
Volume volume25
Issue issue2
Start Page 1
End Page 8
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307559
JaLCDOI 10.18926/15491
FullText URL Mem_Fac_Eng_OU_24_2_11.pdf
Author Sakakibara, Akira| Kanadani, Teruto|
Abstract Aging behavior of Al-0.23mass % Si alloy was studied by measurements of elecrical resistivity. Resistvity maximum was observed in the aging curves at 273K after quenching from various temperatures. Appearance of maximum and its dependence on the quenching temperature were attributed to the formation of GP zones. Even in a more dilute alloy as 0.01mass % Si, the maximum of resistivity was also recognized.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-03-29
Volume volume24
Issue issue2
Start Page 11
End Page 16
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307615
JaLCDOI 10.18926/15489
FullText URL Mem_Fac_Eng_OU_24_2_1.pdf
Author Umemoto, Masayuki| Takemoto, Yoshito| Sakakibara, Akira| Hida, Moritaka|
Abstract Fine particles of Ti-Mo alloy were prepared by evaporation. When Ti-40at % Mo alloy was evaporated on tungsten filament, fine particles of Ti contaminated with W were obtained. These particles were polyhedron in shape and 10~250nm in diameter. Average diameter and size distribution increased with pressure of argon gas (100~600 Torr). When pure Ti was placed on the Mo filament and evaporated from melt down of heated Mo filament in helium gas, fine particles of pure Ti and of Ti-Mo alloy were obtained. In this case, Ti particles were of indeterminate form and of several tens nm in diameter, and their diffraction pattern was of common α-Ti. On the other hand, composition of the Ti-Mo particles was determined to be 18at % Mo by an analysis of EDX. Structure of Ti-Mo particles could not be determined because their diameters were more than 600nm. The temperature of Mo filament, for the most part, was about 1800℃, and there pure Ti particles were produced. The temperature of the fused part of the filament was locally higher than 2600℃, and there Ti-Mo particles were produced. Fine structures of contact region among some Ti particles were observed with HRTEM.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-03-29
Volume volume24
Issue issue2
Start Page 1
End Page 9
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307765
JaLCDOI 10.18926/15484
FullText URL Mem_Fac_Eng_OU_25_1_15.pdf
Author Sakakibara, Akira| Kanadani, Teruto|
Abstract Aging of Al-lmass % Ag alloy at 273K after quenching under various conditions was studied by measurement of electrical resistivity. Scattering of the quasi-equilibrium value of resistivity (p(e)) was not random but closely related to the as-quenched value (p(o)); P(e) increased with increasing p(o)' When the quenching temperature (T(q)) was lower than or equal to 773K, the state at p(e) was controlled substantially by the concentration of quenched vacancy. On the other hand, when T(q)>823K, GP zones formed during quenching played an important role, instead of quenched vacancies, in determining the state.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-12-14
Volume volume25
Issue issue1
Start Page 15
End Page 21
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307255
JaLCDOI 10.18926/15469
FullText URL Mem_Fac_Eng_OU_23_2_1.pdf
Author Kamiyabu, Hideto| Sakakibara, Akira| Maeda, Hironobu| Hida, Moritaka|
Abstract Surface tension (γ(L)) and contact angle (θ) of gallium related to wettability on Teflon and other substrates (Al(2)O(3), SiO(2), glass, graphite, BN, AI, Ni, As etc.) were investigated. The values of Teflon were 0.70(6)N/m and 158° in pure argon atmosphere, and the ones of other substrates were listed in a table in this text. We were interested especially in the relative values, γ(L)'s, on the substrates as compared with γ(L) on Teflon substrate. Liquid Ga showed spreading wetting on pure Ni metal and adhesional wetting on Al (supposed to be covered by A1(2)O(3)) and on metallic polycrystal As. Surface tension of Ga was remarkably decreased by a kind of oxide contamination due to oxygen in air. The surface layer coated by the contamination was of amorphous state nearly same as liquid Ga. The amorphous coat caused liquid Ga rather high supercooling of △T~35K. It seems that the contamination layer (oxide fi1m) smeared the crystal nucleation sites on the free surface of liquid Ga
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1989-03-30
Volume volume23
Issue issue2
Start Page 1
End Page 8
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307294