著者
花田 修治 渡辺 貞夫 佐藤 敬 和泉 修
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
vol.45, no.12, pp.1279-1284, 1981 (Released:2008-04-04)
参考文献数
30
被引用文献数
5 or 0

Magnetic heads made of Sendust alloy head cores (standard chemical composition: Fe-9.6 wt%Si-5.4 wt%Al) are known to have superior magnetic properties and wear resistance. The cores are usually made by mechanical working, such as slicing and grinding since the alloy is so hard and brittle that it has been believed to be difficult to make head cores by plastic deformation. In the present work, plastic deformability of the alloys was investigated by compressive tests on Sendust single crystals at temperatures between room temperature and 1173 K and various strain rates. Main results are summarized as follows.The operative slip systems are {110}〈111〉 and {112}〈111〉 depending on compressive axis. Therefore, the von Mises criterion for a polycrystalline material to deform plastically by slip within grains is satisfied, indicating that the brittleness of Sendust alloys cannot be explained by the number of independent slip modes available. At room temperature the stress-strain curve exhibits three stages in a similar manner to Fe3Al and Fe3Si with DO3 structure.Above the temperature where yield stress decreases abruptly, the steady state deformation takes place. Under the condition of the steady state deformation, the strain rate is represented by the relationship of \dotε=Bσnexp(−Q⁄kT), where n=4.6 and Q=540 kJ/mol. These results suggest that even a polycrystalline material of Sendust alloy may be deformable under the suitable conditions.
著者
清水 謙一
出版者
公益社団法人 日本金属学会
雑誌
まてりあ (ISSN:13402625)
巻号頁・発行日
vol.37, no.8, pp.655-658, 1998-08-20 (Released:2011-08-11)
参考文献数
27
著者
星 恵理子 北田 正弘
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
vol.67, no.7, pp.336-341, 2003 (Released:2008-04-24)
参考文献数
12

The effects of Cu-containing pigments on degradation of Japanese paper have been investigated. A hand-coloured wood-block print of the late Edo era is used as a naturally aged specimen. To clarify the degradation mechanism, sheets of modern Japanese paper painted with powdered malachite are aged in an environment of 353.15 K(80°C), 65%RH. Pigments are examined with XRD. Degradation of the paper is examined with a three-dimensional fluorescence spectrometer. Cu content in the specimen is measured by ICP-AES and EDS. The Cu concentrations of the cross-sections of naturally aged specimen decrease with increasing depth. In addition, the Cu concentrations at the same depth of the artificially aged paper increase with aging. These results show that the Cu species diffuse from the right to the wrong side of the paper. Although the green pigment of wood-block print contains Cu species and As species, only the Cu species has been detected in the fiber of the degraded part of the paper. The degree of degradation of the accelerated sample painted with malachite becomes higher than that of the unpainted sample. Therefore Cu is the main species that participates in the degradation of paper. The fluorescence intensity of the papers painted with malachite decreased with increasing aging time. This result shows that diffused Cu ions make impurity levels in the band gap of cellulose.
著者
加藤 雅治
出版者
公益社団法人 日本金属学会
雑誌
まてりあ (ISSN:13402625)
巻号頁・発行日
vol.47, no.5, pp.256-261, 2008-05-01 (Released:2011-08-11)
参考文献数
7
被引用文献数
1 or 0
著者
土屋 正行 泉山 昌夫 今井 勇之進
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
vol.29, no.4, pp.427-433, 1965 (Released:2008-04-04)
参考文献数
24
被引用文献数
2 or 0

The investigation on the transformation of austenite to martensite based on the statistical thermodynamics was carried out using the iron-nitrogen binary alloys containing about 1.8 to 2.8 weight per cent nitrogen. The result of this treatment was compared with that of the iron-carbon binary alloys. The Ms point which was determined microscopically by the Greninger and Troiano method descends with the increase of the nitrogen content and attains room temperature at about 2.2 weight per cent nitrogen showing a complete austenitic structure. Ms points of the iron-nitrogen and iron-carbon alloys containing the same atomic percentage agreed with each other. The T0γ−α′ temperature (ΔFγ→α′=0) of the iron-nitrogen alloy fell nearly parallel to the change in the Ms point with increase of the nitrogen content. On the other hand, the driving force necessary for initiating the martensite transformation increased with increase of the nitrogen content. The effect of carbon on the thermodynamic properties of martensite transformation agreed with the effect of nitrogen. Stabilities of martensites and supersaturated ferrites of the nitrogen- and the carbon-iron alloys were also discussed.
著者
新里 秀平 譯田 真人 尾方 成信
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
(Released:2016-01-22)
参考文献数
25

It is well known that the mechanical strength of iron is significantly changed by alloying. However, atomistic origin and underlying mechanism are still unclear. Since the strength change with respect to solute concentration is very sensitive and highly non-linear, the way of empirical prediction may contribute little to designing the mechanical strength by alloying. In this study, we theoretically construct a model which predicts temperature, strain rate, and solute concentration dependencies on critical resolved shear stress (CRSS) and yield stress of BCC iron alloys with dilute substitutional solutes based on atomistic analysis of the dislocation-solute atom interaction. In the coarse-grained BCC polycrystalline metals, the mechanical strength and deformation are dominated by screw dislocation motion consisting of kink nucleation and migration processes. Thus, our model is based on atomistically computed activation free energies for kink nucleation and migration of screw dislocation. We eventually apply our model to Fe-Si dilute alloy system as a representative example of BCC dilute alloys, and the theoretically predicted CRSS by our model is compared with an experimental one.
著者
吉田 浩一 大中 逸雄
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
vol.61, no.4, pp.342-349, 1997 (Released:2008-04-04)
参考文献数
20

An algorithm has been developed for simulating the solidification in copper billet continuous casting based on the direct finite difference method by assuming a flow field in the melt. The simulation model considers the temperature dependent thermo-physical properties, convection heat transfer due to the movement of liquid and solid phases, latent heat of solidification and heat transfer among carbon and copper molds, billet and cooling water. The simulation results were compared with a measured sump shape, cooling curves and dendrite-arm-spacing (DAS). The sump shape was estimated from the solidification structure obtained by adding molten Sn during casting. An experimentally determined relationship between DAS and cooling rate was used in the estimation of the DAS distribution in the billet. The comparison between calculated and measured results showed a good agreement and it was found that neglecting the heat transfer into the casting direction results in a maximum error of 16.4%. It was also found that a more accurate estimation of the thickness of the solidified layer and temperature near meniscus requires more accurate information on the velocity field.
著者
國貞 雄治 坂口 紀史
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
vol.80, no.9, pp.570-574, 2016 (Released:2016-08-25)
参考文献数
24

We have investigated trapping effects of monoatomic vacancies Vmono and alloy atoms on hydrogen diffusion at Al(111) surfaces. We performed first-principles calculations based on density functional theory with generalized gradient approximation in order to obtain the hydrogen adsorption energies in the vicinity of monoatomic vacancies and alloy atoms in Al(111) subsurfaces. We considered Si, Cr, Mn, Fe, Cu, Ge, and Zn as alloy atoms. We substituted one Al atom with one monoatomic vacancy or alloy atom, which corresponds to Al0.95X0.05(111) (X=Si, Cr, Mn, Fe, Cu, Ge, Zn, Vmono) surfaces. We found that all of monoatomic vacancies and alloy atoms increase adsorption energies. We also clarified that hydrogen atoms make strong covalent bonds in Cr, Mn, Fe-alloyed Al(111) subsurfaces, while they make only weak ionic bonds in pure and Si, Cu, Ge, Zn-alloyed Al(111) subsurfaces.
著者
小川 由希子 安藤 大輔 須藤 祐司 小池 淳一
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
vol.80, no.3, pp.171-175, 2016 (Released:2016-02-25)
参考文献数
25
被引用文献数
4 or 0

Mg-20.5 at% Sc alloy with hcp (α)+bcc (β) two-phase alloy was investigated to understand the effects of aging treatment at 200℃ on microstructure, hardness and tensile properties. The Mg-Sc alloy ingot was prepared by induction melting in Ar atmosphere, and then hot rolled at 600℃ followed by cold rolling into a sheet. The rolled specimens were annealed at 600℃ to obtain α+β two-phase microstructure. Then, the annealed specimens were aged at 200℃ for various time. Vickers hardness of the α+β two-phase alloy drastically increased after a certain incubation time and then reached maximum hardness of 142.8 Hv. The incubation time of the Mg-20.5 at% Sc alloy with the α+β two-phase was longer than that of the same alloy with a β single-phase. Ultimate tensile strength (UTS) and elongation of the as-annealed specimen were 280 MPa and 28.2%, respectively. Meanwhile, the specimen aged at 200℃ for 14.4 ks showed a UTS of 357 MPa and an elongation of over 12%. The specimen aged for 18 ks showed a higher UTS of 465 MPa while keeping a better elongation of 6.9%. It was found that the age hardening of the Mg-Sc alloys were attributed to the precipitation of very fine α phase in β phase.
著者
Wang W. G. Matsugi K. Fukushima H. Sasaki G.
出版者
公益社団法人 日本金属学会
雑誌
MATERIALS TRANSACTIONS
巻号頁・発行日
vol.48, no.7, pp.1948-1954, 2007

AZ91D magnesium alloy reinforced with aluminum borate whisker (Al<SUB>18</SUB>B<SUB>4</SUB>O<SUB>33w</SUB>, denoted by ABO<SUB>w</SUB>) was fabricated by squeeze-casting. The heat treatment (T4) was carried out at 693 K in argon atmosphere for 48 and 96 hours, respectively, following water-quenched. The behaviors of interfacial reaction were studied in processes of fabrication and following heat treatment. Microstructures of interfacial reaction layers were investigated with transmission electron microscopy (TEM). Interfacial reaction layer in thickness of 5&ndash;10 nm was found in as-casted composite, and it was identified that the interfacial reaction layer was consisted of MgO. When the composite was heat-treated at 693 K for 48 hours, the surfaces of whiskers were covered with interfacial reaction layer completely and the thickness of interfacial reaction layer increased to about 20 nm. With increasing the time of heat treatment from 48 hours to 96 hours, the thickness of interfacial reaction layer on the surfaces of whiskers did not change obviously. The interfacial reaction layer was consisted of tiny MgO particles and a small quantity of MgB<SUB>2</SUB> particles. Although MgO particles played a good barrier to keep out of contacting between magnesium and whisker, the boundaries between MgO particles acted as a shortcut of magnesium atoms migration. Therefore magnesium could keep on reacting to whisker. The interfacial reaction could invade into the inner of whisker about 20 nm depth after the composite was heat-treated at 673 K for 96 hours. The surfaces of whiskers became wave-like because of interfacial reaction. An orientation relationship was found between MgO reaction layer and ABO<SUB>w</SUB>: (11\\bar1)<SUB>MgO</SUB>||(320)<SUB>ABOw</SUB> and [011]<SUB>MgO</SUB>||[001]<SUB>ABOw</SUB>. The surfaces of MgO particles were consisted of close-packed (111)<SUB>MgO</SUB> plane.
著者
釘屋 奈都子 永田 和宏 北田 正弘
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
vol.78, no.4, pp.149-158, 2014 (Released:2014-04-01)
参考文献数
14

The manufacturing technique of steel chains used for four Japanese armatures from the end of Muromachi to the Edo period has been investigated. The chains used in Kusazuri (tasset) and two types of Kote (guntlet) were composed of steel rings in round and oval shapes while those used in Kusarikatabira (chainmail) was only round. As for the former ones, round rings were connected by oval rings. The diameter of steel wire of rings was about 1 mm. The steel wire was produced from steel plate with the carbon content of 0.11 to 0.40 mass%. Steel was forge-and-welded twice to make in plate and was cut in a bar. The steel bar was drawn into standardized wires by die with the draft percentage of about 25% and annealed. Drawing of standardized wire followed by annealing was repeated several times to make a wire for armatures. The crystal grains in wires were elongated in axial direction and the aspect ratio of grain in oval rings was larger than that in round rings. A wire was rolled around a stick and cut by chisel to make rings.
著者
馬越 佑吉
出版者
公益社団法人 日本金属学会
雑誌
まてりあ (ISSN:13402625)
巻号頁・発行日
vol.51, no.5, pp.203-208, 2012 (Released:2012-12-27)
参考文献数
20
被引用文献数
1 or 0
著者
小岩 昌宏
出版者
公益社団法人 日本金属学会
雑誌
まてりあ (ISSN:13402625)
巻号頁・発行日
vol.39, no.1, pp.58-62, 2000-01-20 (Released:2011-08-11)
参考文献数
13
著者
増本 健 奈賀 正明 今井 勇之進
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
vol.34, no.2, pp.195-201, 1970 (Released:2008-04-04)
参考文献数
21
被引用文献数
1 or 0

Studies on the equilibrium between austenitic iron and nitrogen under various conditions of the maximum pressure of 920 kg/cm2 and the temperature range of 950°∼1300°C were carried out using a high temperature-high pressure equipment. It was shown that the concentration of nitrogen in austenite deviates from Sieverts’ law with increasing pressure. The cause for such discrepancy was considered thermodynamically and statistically. That is, the experimental result can reasonably be explained from the geometrical consideration that the chemical potential of a nitrogen atom in austenite with a high nitrogen content, departs remarkably from the value for the ideal random interstitial solid solution, since each interstitial atom added excludes other interstitial atoms from the seven adjacent sites. Thus, the activity of nitrogen in austenitic iron can be expressed by the following equations:(This article is not displayable. Please see full text pdf.)
著者
平山 俊成 小切間 正彦
出版者
公益社団法人 日本金属学会
雑誌
日本金属学会誌 (ISSN:00214876)
巻号頁・発行日
vol.34, no.5, pp.507-510, 1970 (Released:2008-04-04)
参考文献数
21
被引用文献数
17 or 0

In order to investigate the martensitic transformation in Fe-Cr-Ni stainless steel, the Ni equivalent has been introduced thermodynamically as a universal quantity which indicates stability of austenite with regard to chemical composition. The relation between the Ni equivalent and the amount of strain-induced martensite or athermal martensite has been studied by means of saturation flux density measurement. Furthermore, the mechanism of the formation of strain-induced martensite has been considered thermodynamically.The results obtained are summarized as follows:(1) The Ni equivalent, (Ni), in Fe-Cr-Ni stainless steel is expressed by\phantom(1)(Ni)=Ni+0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6C\ oindentwhere Ni, Cr, etc. represent weight % of these elements in the stainless steel considered.(2) The relation between the Ni equivalent and the amount of strain-induced or athermal martensite has been obtained.(3) About 75% cold rolling of Fe-Cr-Ni stainless steel has the same effect on martensitic transformation as decreasing the Ni content by 3∼5%. In this case, the difference in the free energy at room temperature between the ferrite phase and the austenite phase increases by about 113∼188 cal/mol.(4) The deduced value of the work done by transformation strain induced by the applied stress due to cold rolling is about 120∼126 cal/mol or about 192 cal/mol by compressive or tensile stress, respectively. These values agree very well with the above mentioned change of the free energy difference calculated from the variation in Ni equivalent. Therefore, under applied stress, the stored free energy required for martensitic transformation can be lowered by this work value, 120∼192 cal/mol.