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Volume 39, Issue 5
Displaying 1-18 of 18 articles from this issue
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Koichi Fujiwara, Yoichiro Yamaguchi1975 Volume 39 Issue 5 Pages 429-436
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe mechanism of metal adhesion and transfer between contacting metals was examined under the condition that the surface film was broken down electrically. Measurements were made on the amount of metal transfer, adhesion force and contact resistance with the crossed-rod contact configuration. The amount of metal transfer was measured by the γ-counting of transferred 198Au and 64Cu activated by thermal neutron irradiation. Under a 10 g contact load, the amount of metal transfer of Au ranged from 5×10−10 to 2×10−5 g with increase in current from 0.1 to 380 A and that of Cu ranged from 2×10−11 to 7×10−8 g. The contact voltage was estimated from contact resistance and current. The softening voltages of Au and Cu were 50 and 75 A, respectively. The melting voltage of Au was 300 A and that of Cu was not attained with the current up to 380 A. Below the softening voltage, the metal transfer of Au was the same as that above the softening voltage and that of Cu was very small. This is considered that the surface film influences metal adhesion and transfer. Above the softening voltage, the surface film was broken down completely and the metal transfer increased with contact current irrespective of Au or Cu. The adhesion forces of both Au and Cu above the softening voltage coincided satisfactorily with their tensile strengths multiplied by the real contact area. The temperature rise of the contact surface due to the Joule heat was estimated from the Vickers hardness at high temperature and contact resistance. Reasonable results were obtained and the self-diffusion caused by this temperature rise was estimated to be small enough compared with metal transfer.View full abstractDownload PDF (710K) -
Kenki Hashimoto, Tokuzo Tsujimoto1975 Volume 39 Issue 5 Pages 436-444
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy using a X-ray Guinier camera, diffraction photographs were taken for both plate and powder specimens of the alloy aged at 500∼800°C. The patterns containing side-bands were analysed and the following characters were obtained.
(1) Side-bands were observed on each side of the main diffraction line, i.e. at the diffraction angle θ±Δθ, for both of the aged plate and powder specimens. For the aged powder specimens, an additional diffraction line M1 appeared at a high-angle side of the main diffraction line, i.e. at θ+Δφ. The values of tanθ⁄Δφ for the M1 line and the values of Q(=(tanθ⁄Δθ)·h⁄(h2+K2+l2)) for the side-bands were independent of the Miller indices of the main diffraction lines.
(2) The M1 line was considered to be diffracted from the solute depleted zone which was caused by the existence of oxide film formed during quenching. It was concluded that except for the existence of the M1 line in the powder specimens, the aging process in the powder specimens does not essentially differ from that in the plate specimens.
(3) In a later stage of aging, the low-angle side-band became broadened and then splitted into a new low-angle side-band and a line of α2-phase.
(4) After an incubation period on the variation in Q, the values of Q increased in proportion to the cubic root of aging time.View full abstractDownload PDF (731K) -
Goro Omori, Shigeru Matsuo1975 Volume 39 Issue 5 Pages 444-451
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffect of plastic deformation on the precipitation process of Mg-1.3 wt%Ce alloy was investigated by electrical resistivity measurement, hardness measurement and electron microscopy.
On isochronal annealing, the critical temperature range in which a marked decrease in resistivity occurred for the deformed specimen was lower than that of the undeformed one.
On isothermal annealing at 200 and 220°C, the resistivity decreased in two stages. Following Johnson-Mehl equation, the values of 1/2 and 1.0 were obtained as the time exponents, n, for the first and second stages, respectively. Using the isothermal curves of resistivity change, the estimation of apparent activation energies for the above two stages was made. In the first stage, the activation energy increased as the precipitation proceeded, whereas it was nealy constant throughout the second stage.
On annealing at 125∼200°C, the time needed to reach the peak hardness decreased logarithmically with the amount of prior deformation within a range 0∼37% reduction. The relationship between logarithm of maximum hardness attained by annealing and the logarithm of conventional strain was shown to be linear.
Electron microscopic examination revealed that with increasing amount of deformation the equilibrium precipitates nucleated on dislocations were easily observed at shorter annealing time at moderately high temperatures. The intermediate precipitates nucleated within the matrix were observed for the alloy deformed by a few per cent reduction. It was shown that the ribbon shaped equilibrium phase grew mainly in the direction of ⟨0001⟩ and, to a lesser extent, in the direction of ⟨11\bar20⟩ of the matrix.View full abstractDownload PDF (826K) -
Goro Omori1975 Volume 39 Issue 5 Pages 451-459
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe recrystallization process of cold-rolled polycrystalline magnesium and magnesium alloys containing 0.04∼2.65 wt% of cerium was investigated by hardness measurement, the X-ray pinhole method, and optical and electron microscopy.
Primary recrystallization temperature was increased with increasing cerium content up to the maximum solid solubility. The recrystallization temperature of primary recrystallization within the compression bands and twins was lower than that in the other region. The crystallized grains in compression bands were fine compared with those in the other region. On further heating, recrystallized grains became uniform all over the specimen.
On isochronal annealing, little difference was found in the primary recrystallization temperature of Mg-1.3 wt%Ce alloy, regardless of prior precipitation treatment before final cold rolling. Decrease in hardness occurred in two stages for the alloy precipitation-treated before cold rolling, whereas it occurred in a single stage for the alloy without precipitation treatment.
The isothermal annealing curves of precipitation treated Mg-1.3 wt%Ce alloy were analyzed by the Johnson-Mehl equation. The value of 3 was obtained as the time exponent in the early stage.
The resistance to recovery and recrystallization was attributed mainly to the presence of precipitates on dislocations, and at subgrain and grain boundaries. Also, the presence of cerium atoms in solution under equilibrium seems to exert an effect, since the diffusivity of cerium in magnesium below about 550°C is smaller than that of self-diffusion of magnesium.View full abstractDownload PDF (1605K) -
Mitsunori Tsutsui, Naomasa Fujise1975 Volume 39 Issue 5 Pages 460-466
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to clarify the kinetics of hydrogen absorption in Ti during galvanostatic cathodic polarization in 4N H2SO4, the hydrogen content was determind by solid state vacuum extraction at 900°C and the surface layer was examined by means of X-rays and an ion microprobe mass analyzer. In addition, cathodic and anodic polarization behavior of Ti hydride was examined using the galvanostatic and potentiostatic methods.
The results obtained are as follows:
(1) Both the fct and fcc types of Ti hydride were formed at low c.d. but only the fcc type was formed at high c.d. The lattice constant of the fcc type was a=4.410∼4.25 Å.
(2) The rate of hydrogen absorption increased with increasing c.d. up to 20 mA/cm2, above which the rate was independent of c.d. The rate showed a larged temperature dependence. The diffusion coefficient of hydrogen in Ti was 5∼7×10−12 cm2/sec.
(3) Hydrogen in the surface layer was oxidized but internal hydrogen was stable during anodic polarization of Ti-charged hydrogen.
The unitary formation rate (R) of the TiO2 film or the reciprocal capacitance (1/C) calculated from the gradient of the E-t curve was linearly related to logi. The rate decreased with increasing hydrogen content in Ti.View full abstractDownload PDF (598K) -
Fukuji Inoko, Hiroshi Yamaji, Koichi Akizono, Genjiro Mima1975 Volume 39 Issue 5 Pages 467-476
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTensile properties of aluminum bicrystals with Σ7 coincidence boundary and the corresponding “pseudo-bicrystals” (component single crystals strained in parallel) were compared.
It has been confirmed that the presence of crystal boundary promotes the deformation of the bicrystal under the following conditions:
(1) The crystal boundary acts as the dislocation source.
(2) The value of Nij between the primary slip systems of two component crystals is large.
(3) The compatibility between the adjoing crystals is good.
(4) The forces between the dislocations on the primary slip systems of crystal A and B pull each other, so that the crystal boundary acts as dislocation sink.
(5) The interaction between the dislocations on different slip systems near a crystal boundary may soften either or both of the two crystals. For example, by its mutual action the formation of Lomer-Cottrell sessile dislocations may be disturbed.
The relation between strain and the boundary strength (the increase of the strength of bicrystal by the presence of boundary) was obtained. The maximum value obtained was about 400 g/mm2 at 5×10−2 strain in the specimen Type 3.
It was concluded that the long range stress field by the wall of parallel screw dislocations either attractive or repulsive to the approaching screw dislocations contributed to the boundary strength.
The plastic deformation was affected by the newly created dislocation network in the boundary as well as by the structure of the existing boundary.View full abstractDownload PDF (1086K) -
Takeshi Nagai, Zenzo Henmi, Takakazu Yamamoto, Shigeyasu Koda1975 Volume 39 Issue 5 Pages 477-483
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFrom the previous studies on recrystallization behavior of precipitation hardening alloys, including our previous papers, it is known that the equilibrium diagrams of the alloys in which fine particles hinder recrystallization, have very small maximum solid solubility.
In the present paper, in order to study the effect of the maximum solid solubility on recrystallization in Cu-base alloys, recrystallization behavior of Cu alloys containing 1 at% each of Zr, Cr, Cd, Ag, Co and Ni were studied by the resistometric method, tensile strength measurements and transmission electron microscopy after quenching and severe cold working. The recrystallization temperatures were obtained by tensile strength measurements.
The experimental results revealed that the recrystallization temperatures were high in the alloys of small maximum solid solubility. A possible explanation of this result is that solute atoms of small solid solubility can exist stably as fine precipitate particles, which hinder dislocation annihilation and grain boundary migration.View full abstractDownload PDF (785K) -
Kazuaki Fukamichi1975 Volume 39 Issue 5 Pages 484-488
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInvar alloys have wide applications of control devices and precision instruments such as bimetallic thermostats and standard scales. But the practical Invar alloys are all ferromagnetic and applications of these alloys are often restricted because of their ferromagnetism. Therefore, it is important to carry out research for development of magnetically insensitive Invar alloys.
Since there is no remarkable crystal anisotropy in thermal expansion in cubic alloys, it is impossible to obtain magnetically insensitive Invar alloys by metallurgical methods. Thus, any attempt to obtain such an Invar alloy should be based on the anomalous volume change resulting from the appearance of antiferromagnetism.
Cr is an antiferromagnetic metal and its physical properties around the Néel temperature such as thermal expansivity and electrical resistivity are drastically changed by the addition of solute atoms. The concentration dependence of the Néel temperature of Cr primary solid solution alloys containing a 4d transition metal or Fe indicates that the addition of Ru or Rh raises the Néel temperature, while the addition of Fe decreases it.
Taking into consideration these effects on the Néel temperature, we discovered that some Cr-Fe base ternary alloys containing a 4d transition metal show magnetically insensitive Invar characteristics.View full abstractDownload PDF (405K) -
Tadashi Takemoto, Shigenori Hori1975 Volume 39 Issue 5 Pages 488-493
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn previous work the authors reported that the aged Cu-4%Ti alloy showed high stress corrosion cracking susceptibility. Mainly the propagation of intergranular cracks led to the failure of this alloy. Only intergranular cracks were found in as-quenched specimens, but inter- and transgranular cracks were coexisted in aged specimens. In this work we attempt to clarify the cause of the formation of transgranular cracks in aged specimens, and to propose the stress corrosion cracking machanism for this alloy. Specimens were subjected to static tensile load in aqueous ammonia containing cupric complex ions. We obtained the following results: (1) The relation between the depth of stress corrosion cracks and the aging time at 450°C showed the maximum depth in the specimen aged for about 1 hr. (2) Chemical analysis of the corrosive solution after stress corrosion tests revealed that preferential dissolution of copper had occurred during stress corrosion process and that Ti was quite difficult to dissolve. (3) The stress corrosion cracking susceptibility of this alloy was tightly dependent on the growth of modulated structure during the aging process. The growth of the modulated structure leads the change of the ratio of anodic area to cathodic area of local corrosion cells, which influences the stress corrosion cracking susceptibility. Increasing in cathodic area accelates active anodic dissolution and enhances the atress corrosion cracking susceptibility.View full abstractDownload PDF (519K) -
Masaaki Fukuchi, Katsuya Watanabe1975 Volume 39 Issue 5 Pages 493-498
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effects of temperature and composition on hardness, electrical resistivity and thermoelectric power of the γ-phase were studied in relation to a covalent component of interatomic forces. From the temperature dependence of resistivity and thermoelectric power, it was possible to assume the existence of a narrow energy band of high density which seems to be related to a homopolar Al−-Al− bond. The strength of the bond appears to be affected by an introduction of compositional defects. When the composition of the γ-phase deviates from stoichiometry, the strength would be reinforced by excess aluminum but weakend by excess magnesium. The temperature of hardness-softening is relatively high, 0.72–0.79Tm, suggesting the contribution of the homopolar bond to the mechanical properties of the compound.View full abstractDownload PDF (520K) -
Kiyoshi Watanabe1975 Volume 39 Issue 5 Pages 498-502
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe magnetic moments and magnetic transformation temperatures of Mn base C1b-type compounds have been investigated in relation to the neighbouring Mn atoms, Mn-Mn interatomic distances and valence electron numbers.
The results show that the magnetic interactions of these C1b-type compounds are dependent upon the kind of neighbouring Mn atoms. The variation of the Mn-Mn interatomic distance in stoichiometric C1b-type compounds can be ascribed to the variation of the Curie temperature rather than the saturation magnetic moment per Mn atom. For various C1b- and L21-type compounds, the valence electron number per atom and the ferromagnetic and paramagnetic Curie temperatures can be represented by a characteristic curve. The Curie temperatures of C1b-type compounds NiMnSb, PtMnSb and PdMnSb in equivalence per chemical equation decrease gradually with increasing Mn-Mn interatomic distance. With increasing Mn-Mn interatomic distance, the paramagnetic Curie temperatures of CuMnSb, PdMnTe and AuMnSb which are one valence higher than the aforementioned compounds increase gradually and the magnetic properties of these compounds change from antiferromagnetic to weakly ferromagnetic.View full abstractDownload PDF (453K) -
Koichi Sugimoto, Keiji Mizutani1975 Volume 39 Issue 5 Pages 503-511
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMeasurements of internal friction and Young’s modulus have been made by a flexural vibration method in a temperature range from −196 to 160°C on three Mn-Cu (55.4–71.2%Mn) and eight Mn-Cu-Ni (69.1–75.3%Mn, 9.4–28.8%Cu, and 4.8–19.9%Ni) alloys, when aged at temperatures from 350 to 500°C after the solution-treatment at 850°C. The effects of composition, aging temperature, and aging time on the temperature behaviors of internal friction and Young’s modulus were investigated. It is found that there are in general four kinds of internal friction peaks in the aged samples; i.e., P1 and P2: low-temperature peaks at −160 and −110°C, respectively, P3: a twin-boundary relaxation peak at 10°C, and P4: a phase transformation peak at a temperature which is 20 to 30°C lower than that of the martensitic transformation in each sample. It has been confirmed that the latter two peaks are responsible for the high-damping property of the alloy. Besides, there are anomalies of the Young’s moduli at the temperature of the martensitic transformation. It is concluded that the aging treatment can raise considerably the transformation temperature in binary alloys and also in a 69Mn-26Cu-5Ni alloy, the activation energies for the aging process being about 38.4–45.4 kcal/mol. The addition of Ni by more than 10% suppressed the aging effect almost completely. A model of copper-cluster formation was proposed for the understanding of the aging mechanism and the effect of composition on the aging process was discussed.View full abstractDownload PDF (796K) -
Nobuhiko Iwao, Toshio Kainuma, Ryoji Watanabe, Takehiro Shimomura1975 Volume 39 Issue 5 Pages 512-520
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study has been made on the mechanical properties of unalloyed V and V-Ta alloys over the temperature rang from −196 to 1000°C. It was found that the serration was observed in the load-elongation curves. The temperature of serration ranged from 300 to 600°C for the unalloyed V, while in the case of the alloys two serration ranges were found, that is, the lower range from −196 to −80°C and the higher range from 400 to 700°C.
It is concluded from the microscopic observations that the low temperature serration occured only at the initial stages of deformation for the alloys is due to the deformation twinning. Transition temperature for twinning increases with the Ta content. In this temperature range, the temperature and concentration dependence of the proof stress decreases because the flow stress becomes less pronounced by deformation twinning. Twinning makes the grains finer and the resultant decrease in yield ratio, increases rupture elongation.
In the region of high temperature serration the peak of reverse temperature dependence of tensile strength (the stress increasing with rising temperature) appeared; one peak at about 400°C for unalloyed V and two peaks at about 400 and 700°C for the alloys. This may be ascribed to the dynamic strain aging that is the interaction of dislocation with interstitial impurities for the peak of about 400°C and with substitutional solid solution atoms for that of 700°C.View full abstractDownload PDF (1014K) -
Kozo Hoshino, Masao Kageyama, Shu-ichi Kageyama, Katsuhisa Sugimoto, Y ...1975 Volume 39 Issue 5 Pages 520-528
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPitting potentials and stress-corrosion lives at constant potential of Al-4%Cu alloys with various aging structures were measured in 1M-NaCl. It was found that the alloys having higher susceptibility to stress-corrosion cracking, for example, aged at 170°C for 0.1 day, showed two pitting potentials corresponding to pitting at the grain boundary and the matrix, respectively, and became susceptible to stress-corrosion cracking in the higher potential range than the pitting potential for the grain boundary. In this case, the mode of fracture was intergranular. The susceptibility of the alloys to stress-corrosion cracking was maximum in a 1M-NaCl+1 wt%-H2O2 solution when aged to attain the largest difference in pitting potential between grain boundary and matrix. The alloys solution treated or overaged, which showed the lower susceptibility to stress-corrosion cracking, had only one pitting potential which corresponded to pitting in the matrix. These alloys were subject to stress-corrosion cracking in the higher range than the pitting potential for the matrix and showed the transgranular fracture caused by pitting of the matrix.View full abstractDownload PDF (962K) -
K\={o} Soeno1975 Volume 39 Issue 5 Pages 528-535
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe precipitation process in a maraging steel containing 18%Ni, 10%Co and 5%Mo was investigated by measuring the changes in electrical resistivity at liquid nitrogen temperature and in tensile strength.
Results are interpreted in terms of two types of molybdenum-rich precipitates, a low temperature precipitate and a high temperature precipitate. The low temperature precipitate is formed at 450°C or below, and the high temperature precipitate is formed at 475°C or above. The activation energy for the high temperature precipitate is determined to be about 54 kcal/mol, which is greater than that for the low temperature precipitate, about 35 kcal/mol. A short range ordering process is also considered from resistivity decreases around 350°C in isochronal aging of the maraging steel and a similar steel without molybdenum.
The measurements of the amount and the rate of reversion show that the thermal stabilization of the low temperature precipitate takes place.
Resistivity and strength changes in isothermal aging at temperatures between 475 and 575°C are measured on the maraging steel with and without pre-aging at 425°C for 300 min, and the effects of the pre-aging on strength and precipitation rate are investigated.View full abstractDownload PDF (822K) -
Seita Sakui, Taku Sakai, Teruo Murase1975 Volume 39 Issue 5 Pages 535-543
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEquipment was constructed which enabled metalic materials to be quenched by hydrogen gas immediately after dynamic tension (\dotε=18 sec−1) at high temperatures. With this equipment the deformation behaviours of mild steel (C=0.036 wt%) were studied over the temperature range of 25°C to 1200°C. Measurements of mechanical properties and slip line observations revealed the presence of five temperature regions where mechanisms seemed to be different; (1) the low temperature deformation region between 25 and 300°C, (2) the blue brittleness region between 300 and 600°C, (3) the high temperature deformation region of the α-phase between 600°C and A1 point (723°C), (4) the α-γ mixed phase region between A1 and A3 point (\simeq895°C), and (5) the γ-phase region above A3 point.
True stress vs strain curves in region (3) showed steady state flow in the range of high strain above 40∼50%. The size of subgrains which were formed in the original grains by deformation was nearly constant in the range of high strains and also the values of microhardness and coercive force on specimens which were hot deformed and then immediately quenched were nearly constant in this range. The recrystallized-grains did not appear during hot deformation. They indicate that deformation of α-iron in region (3) is controlled by dynamic recovery.
The structural change due to dynamic recovery is considered to retard or prevent crack initiation, there by leading to increase in hot ductility. The remarkable decrease of ductility with increasing temperature in region (4) may be explained by the fact that most of deformation was concentrated in the region of the α-phase in which flow stress was lower and ductility is larger than that of the γ-phase and consequently non-uniform deformation occurred considerably.View full abstractDownload PDF (1123K) -
Satoshi Fukuda, Ky\={o}ji Tachikawa1975 Volume 39 Issue 5 Pages 544-549
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFormation of the Nb-Ga intermediate phases by the diffusion reaction and the superconducting properties of the Nb3Ga tape were studied. Six intermediate phases, i.e. NbGa3, Nb2Ga3, NbGa, Nb3Ga2, Nb2Ga and Nb3Ga were identified by anodized-oxidation and X-ray microanalysis in the diffusion specimens. The Nb3Ga tape was prepared by the following procedure. First, the Nb-Ga diffusion tape was made by diffusing gallium from the surface of the niobium substrate. The tape was sandwiched by niobium foils and then cold rolled. Finally, the laminated-tape was heat treated at a temperature between 800 and 1900°C. A high superconducting transition temperature was obtained in the Nb3Ga tape heat treated at 1800°C for a short time and then at 800°C for 50 hr. The transition of the tape showed an onset temperature of 20.5 K and a midpoint temperature of 19.2 K. The critinal current density Jc of the Nb3Ga was increased by nearly one order of magnitude by the secondary heat treatment at 800°C. Jc of 3.5×104 A/cm2 was obtained in a transverse magnetic field of 65 kOe for the Nb3Ga layer. A composite of the Cu-Ga alloy matrix and a niobium core was fabricated into a tape and then heat treated. The Nb3Ga layer, however, was not formed in the composite-processed tape.View full abstractDownload PDF (666K) -
Takasi Takezawa, Toru Yokoyama1975 Volume 39 Issue 5 Pages 550-551
Published: 1975
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (141K)
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