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Volume 41, Issue 11
Displaying 1-18 of 18 articles from this issue
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Shigetomo Nunomura, Kenichi Tsunakawa1977 Volume 41 Issue 11 Pages 1087-1093
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe toughness of a 7075 precipitation hardening aluminum alloy was investigated in various heat treated condition. The behaviour of 10 Å radius GP zones was made clear from the variation in electric resistance during isothermal aging at the temperatures of 50, 80 and 120°C. 50 Å radius particls were detected from an early stage of 120°C isothermal aging by the X-ray small angle scattering observation. It was assumed that the maximum hardness observed during 24 h aging at this temperature was due to 50 Å radius GP zones and η′ intermediate precipitates. No zone was observed in the specimen aged above 160°C. In the specimens aged for 24 h, the elongation in the tensile test decreased with increasing aging temperature up to 180°C, and recovered a little at 230°C. An instrumented Charpy impact bending test using the fatigue cracked specimen was made for the plane strain fracture toughness measurement. The value for the fracture characteristic, KQ, calculated from the energy to make an unit fracture surface was used instead of the effective KIC. This value was minimum at an isothermal aging temperature of 140°C in contrast to the elongation in the tensile test which was minimum in the case of 180°C aging. The fractography of tensile test specimens revealed that there were no changes corresponding to the variation of the elongation during the tensile test. The fractured surface of the test specimen accounted for the feature of the change in KQ. With respect to the toughness, prolonged aging at 80∼100°C appears to be more preferable to T6 treatment.View full abstractDownload PDF (738K) -
Kiyotsugu Ohji, Keiji Ogura, Yoshiharu Mutoh1977 Volume 41 Issue 11 Pages 1094-1101
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe processes of initiation, growth and coalescence of voids in tensile ductile fracture of 0.15% and 0.35% carbon steels were investigated with reference to the effects of compressive prestrain, pearlite colony morphology and hydrostatic pressure.
Initiation sites of voids in these steels were found to be at cracks generated in pearlite particles during deformation. In the annealed steels, the cracks began to appear at a relatively small strain level and the number of the pearlite colonies with cracks increased with deformation. Growth of these cracks into voids was rather slow until the stage just before fracture; the formation of voids was rapidly completed at this stage. Coalescence of these voids was found to be triggered and accelerated by microvoids which were nucleated at the final stage of fracture. This triggering action of the microvoids, which, in reality, was one of the most important processes in determining fracture and accordingly fracture strain of a specimen, was quite similar to that previously observed in copper.
Lamellar pearlite particles seemed to be cracked more easily when the lamellae were oriented in the direction of the tensile axis. When the pearlite particles were spheroidized, their cracking or separation from ferrite matrix was remarkably delayed. Under the hydrostatic pressure, retardation of all the foregoing processes, i.e., cracking of pearlite particles, growth of these cracks into voids, mechanical interaction of these voids and nucleation of microvoids, brought about an increase in fracture strain.View full abstractDownload PDF (1433K) -
Keizo Nishida, Harumitsu Murohashi, Tsuyoshi Yamamoto1977 Volume 41 Issue 11 Pages 1101-1106
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIron test pieces were diffusion-annealed in an evacuated silica capsule containing the powdered (100∼200 mesh) 50 wt%Sb-Fe alloy consisting of α and ε phases as an Sb vapor source for 9∼440 hr at 700∼950°C. The test pieces were then analysed with an EPMA and the penetration curves of them were obtained.
Each penetration curve was analysed by means of the Matano-Boltzmann method to obtain the chemical diffusion coefficients (\ ildeD). From these values the activation energies for diffusion (\ ildeQ) were calculated.
Surface concentration of the test pieces (αmax) at each annealing temperature coincided approximately with the solubility observed in the phase diagram of an Fe-Sb system at lower temperatures, while a significant deviation was found in solubility at higher temperatures. Fine alumina makers placed on the test pieces prior to diffusion were found always on the surfaces after annealing so that it is considered that Sb atoms diffuse predominantly in the α-phase of this system. Each penetration curve was similar to an error function curve and \ ildeD at each temperature showed a relatively small dependence upon Sb concentration. There was a gap in the Arrhenius plot owing to magnetic transformation. The activation energies for diffusion (\ ildeQ) obtained from the data at higher temperatures varied from 59.5 kcal/mol for 1 at%Sb to 52.5 kcal/mol for 4 at%Sb and that for impurity diffusion of Sb in iron (QSb*) was evaluated to be about 63 kcal/mol.View full abstractDownload PDF (585K) -
Yuetsu Murakami1977 Volume 41 Issue 11 Pages 1106-1112
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe magnetic and electric properties of Ni-Mn base polynary alloys have been measured. The specimens investigated are Ni-Mn-Me-alloys with less than about 24%Mn, where Me represents V, Nb, Ta, Cr, Mo, W and/or Fe. The permeabilities depend remarkably on chemical composition and heat treatment. The alloy of 79.38%Ni, 8.51%Mn, 5.06%Fe, 3.02%Cr and 4.03%Mo, heated at 1150°C for 3 h and cooled from 650°C to room temperature, exhibits the maximum performance. The highest value of initial permeability is 121000, obtained by the cooling rate of 240°C/h, while the cooling rate of 100°C/h yields the highest value of maximum permeability 643000. In the latter case the coercive force is 1.3 mOe, the magnetic hysteresis loss 0.92 erg/cm3/cycle (for a maximum induction of 2000 G), the saturation induction 2510G and the electric resistivity 84.7 μΩ-cm at 20°C.View full abstractDownload PDF (568K) -
Pongun Son, Tadao Sano1977 Volume 41 Issue 11 Pages 1113-1121
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA simplified derivation of an equation equivalent to that of Sauer and Freise is presented by using the integral expressions of diffusion fluxes. Thus it is clarified that Balluffi’s equation may be brought to completion by supplementing it by the generalized Matano’s equation which describes the location of the original interface when volume changes occur, and that eliminatation of the coordinate of the original interface in Balluffi’s equation leads to Sauer and Freise’s equation.
It is also shown that if one describes the interdiffusion phenomena by the total molefixed reference frame, all the equations not only become simple but also are isomorphic with those described by the ordinary laboratory-fixed reference frame with no volume change.
It is particulary emphasized that the total mole-fixed reference frame would be most adequate for the description of the interdiffusion phenomena accompanying volume changes. The Matano interfaces are also discussed in some detail.View full abstractDownload PDF (721K) -
Shigeki Sasahara, Kazuo Araki, Shigekatsu Mori, Akira Moriyama1977 Volume 41 Issue 11 Pages 1121-1129
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSKinetics of the reaction between iron and zinc in the solid state has been studied at temperatures from 220 to 360°C. Iron-zinc-coupled specimens prepared with the electrodeposition of zinc on the polished iron surface were heated in argon atmosphere at nine different temperature levels between 220 and 360°C.
Depending on the temperature range, three kinds of the growth pattern of the alloy layers were observed as follows. Within a range of 320 to 360°C, both ζ and δ1 phases grew up with the equilibrium boundary concentrations. From 280 to 310°C, a quasi-stable phase pseudo-ζ, having the concentration from stable phase ζ to δ1, was produced after some latent time and grew up as a single phase. Then this phase was separated into the stable ζ and δ1. Under the heating condition between 220 and 260°C, the pseudo-ζ phase was only observed after some latent time.
Except the ζ phase separated from the pseudo-ζ, the growth rates of the product phases of the reaction could be described by the parabolic rate law.
Based on the Al2O3 marker test, it was found that the reaction was controlled by the zinc diffusion in the product layers.
An analytical model of the reaction rate process was developed. All kinds of the growth patterns of the alloy layers observed could be explained by the model developed here and the diffusion coefficients along with other rate constants were determined.View full abstractDownload PDF (784K) -
Kanji Masui, Shigeo Maruno, Toshio Yamada1977 Volume 41 Issue 11 Pages 1130-1136
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe thermal behavior of electrodeposited Ni-P alloys containing 3.2 to 15.8 wt%P (5.9∼26.2 at%P) and the structural transformation or crystalline products associated with the exotherms were investigated by differential scanning carolimetry (DSC), X-ray diffraction and transmission electron microscopy. Moreover, in order to reveal the chemical bonding of phosphorus in the alloys, the P-Kβ soft X-ray emission spectra from the alloys, nickel phosphides (Ni3P and Ni2P) and pure red phosphorus were measured by an electron probe microanalyzer. In the alloys with 3.2≤P≤11.2 wt%, the supersaturated solid solution of P in the fcc Ni structure is transformed into a structure consisting of an aggregate mixture of Ni and Ni3P at 340∼430°C. In the alloys with 12.7≤P≤15.8 wt%, the amorphous solid converts into the metastable single phase at 280∼360°C, and upon further heating this phase is transformed into three different stable phases such as Ni3P plus Ni, Ni3P and Ni3P plus Ni5P2 according to P contents at 430∼460°C. It has been found that the microhardness increases remarkably when the heat treatment of the alloys results in the formation of Ni3P crystals. The P-Kβ X-ray emission spectra of the alloys are quite different in both shape and peak position from those of pure P and resemble gradually those of Ni3P with increasing P content. This fact suggests that phosphorus in the alloys is bonded to nickel by metallic bonds.View full abstractDownload PDF (664K) -
Kenji Matsuki, Yasuhide Ueno, Masao Yamada, Yotaro Murakami1977 Volume 41 Issue 11 Pages 1136-1144
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study of cavitation during superplastic tensile straining of an Al-Zn-Mg alloy has been made using density measurements and metallographic examinations. The main results obtained are as follows:
(1) Both void nucleation and growth processes were associated with grain boundary sliding, and nucleation probably occured at boundaries or triple junctions involving second phase particles such as ZrAl3.
(2) The increase in void volume with the elongation was characterized by three different stages. The exponent of the void volume ratio with deformation time was 1.14–1.20 in stage I and 0.48–0.54 in stage II, respectively.
(3) The final fracture in this alloy occured by void interlinkage across the specimen, which was accelerated by a process of internal necking between the cavities. The maximum fracture elongation was achieved at the highest temperature, 520°C, because the strain-rate sensitivity m and the cavity spacing increased with increasing temperature and, therefore, the rate of internal necking was reduced.View full abstractDownload PDF (1640K) -
Tohru Tanaka, Makoto Kikuchi, Ryohei Tanaka1977 Volume 41 Issue 11 Pages 1145-1153
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe precipitation morphology of Cr2N with hcp structure in 25%Cr-28%Ni-2%Mo austenitic steels containing 0.30, 0.36 and 0.63 wt% nitrogen was studied. In the steels with a 0.3% concentration level of nitrogen, only intergranular precipitates were observed. The coherent twin boundary was not a site favorable for the Cr2N precipitation. In the steel containing 0.63% nitrogen, intragranular precipitates were also observed. The intragranular precipitates of Cr2N were formed on {111} matrix planes as thin plates with a broad face of (00·1)Cr2N. The orientation relationship between the austenitic matrix and the precipitates of Cr2N was {00·1}Cr2N\varparallel{111}γ and ⟨11·0⟩Cr2N\varparallel⟨\bar110⟩γ. The growth of the Cr2N precipitates at about 700°C was accompanied by the generation of dislocations.
Density of the Cr2N precipitates on isolated dislocations was far much smaller than that of precipitates of other interstitial compounds, such as M23C6, in austenitic steels. In the cold rolled steel with 0.63% nitrogen, thin plates of Cr2N precipitated on deformation bands consisting of the planar array of dislocations. At higher aging temperatures where the recrystallization followed by the precipitation took place, the shape of the plate precipitates changed into that of the globular ones with no special orientation relationship with the recrystallized grain after the passage of through a recrystallizing interface.View full abstractDownload PDF (2246K) -
Akitoshi Ishizaka, Seiichi Iwata, Hiroshi Yamamoto1977 Volume 41 Issue 11 Pages 1154-1160
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe mechanism of the thermo-compression bonding of Au wire to Al thin film electrodes on Si semiconductor devices was studied. Because of the importance of breaking the oxide films on Al for obtaining reliable bonds, this investigation was carried out to clarify how the deformation of Au and Al at the bond interface broke the oxide film on Al and made the reaction, or the bond, between Au and Al possible.
The results obtained are as follows:
(1) Even though the plastic strain of Au wire exceeded 40% in thermo-compression bonding, very little macroscopic metal flow was observed on Al at the bond interface. This was explained by the facts that the apparent hardness of Al thin film (1 μm) was affected by the presence of the hard substrate (glass and Si) and that the Al thin film was harder than the bulk Al. This behavior of Al at the bond interface is quite different from that in the ordinary compression bonding of the bulk metals.
(2) The microscopic observation (by SEM) revealed the formation of Au-Al intermetallic compounds along the steps formed on Al by the compression of the Au wire with the traces of slip lines on its surface.
(3) The area of the exposed clean surface, where the oxide films on Al were apparently broken, was directly related to the plastic strain of the Au wire.View full abstractDownload PDF (1083K) -
Seiichi Iwata, Akitoshi Ishizaka, Hiroshi Yamamoto1977 Volume 41 Issue 11 Pages 1161-1165
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the realization of high-speed and highly reliable thermo-compression bonding of Au wire to Al electrodes, the two most important factors were found to be the deformation of Au wire, which breaks the oxide film on Al, and the surface cleanliness of Al. Furthermore, it was found that the bond time (the time during which a load is applied to the bond) could be shortened to about 20 ms (formerly about 200 ms).
The amount of deformation or strain of Au wire was measured, and compared with the bond breaking force. The latter quantity was newly introduced in this study to facilitate the evaluation of bond integrity, and was found to be directly related to the bond failure rate. The bond breaking force was found to increase with the strain, provided the surface cleanliness and the bond time were constant. At the same strain and the bond time, the Al oxide film thickness and the amount of surface contamination were the factors influencing the bond breaking force.
The bond time was found to be determined by the sum of the time required for the plastic deformation of Au and Al and that for the reaction of Au and Al, the former being much greater than the latter. In this study, by increasing the strain rate of Au by applying higher load, the bond time as short as 20 ms was realized.View full abstractDownload PDF (453K) -
Hajime Suto, Hiroshi Takezawa1977 Volume 41 Issue 11 Pages 1166-1172
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSGrain boundary segregations of VB elements (N, P, As, Sb and Bi) and S in as-quenched and tempered 0.6%C-1%Ni-1%Cr steels were investigated by means of Auger electron spectroscopy and scanning electron microscopy. Results obtained are as follows:
(1) From the observation of intergranular fracture surfaces of steels quenched from 1200°C, it was concluded that Bi and S whose solubilities in γ Fe were smaller than 0.2 at%, segregated in the form of droplets, and P, Sb, Mo, and probably N and C whose solubilities in γ Fe were 0.2 to 5%, segregated in the state of atomic adsorption. The grain boundary segregation of As whose solubility is more than several atomic per cent was not so much.
(2) Apparent concentrations of P, Sb and S on the fracture surfaces were increased by about 2, 5 and 1.5 times after tempering at 500°C for 2 h.
(3) On the intergranular fracture surfaces of tempered P and Sb-bearing steels, the segregation of N as well as Ni was observed. On the other hand, the apparent concentration of C on the fracture surface was decreased by tempering.
(4) Some data suggested that the enrichment of Ni took place in the Bi-droplet/γ-matrix interface, and that the austenite grain boundary segregation of P was promoted by alloyed Ni and was restricted by alloyed Mo. Effect of P content on the apparent concentration of Mo on austenite grainboundaries was small.
(5) Apparent P concentration on the austenite grain boundaries slightly decreases with rising temperature.View full abstractDownload PDF (797K) -
Hajime Suto, Shin-ichiro Yamana, Noriyuki Yamaguchi1977 Volume 41 Issue 11 Pages 1172-1179
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStatic and Impact tension tests have been carried out in order to investigate the effects of the aging condition and the deformation speed on the elongation per cent and reduction of area of Al-4.0%Cu and Al-12.6%Ag alloys which aged in the various stages.
The results obtained are as follows:
(1) With increasing impact velocity, the ductility generally increases in a well-known manner and the dimples formed on the fracture surface is enlarged in mean size.
(2) As-quenched specimens and those in the incipient stages of aging have a small amount of precipitates which are the source of void formation. Accordingly, the ductility of these alloys was often decreased by impact tension owing to slipping-off fracture or grain boundary brittle fracture.
(3) Grain boundary ductile fracture takes place in the static tension of fully aged or over-aged alloys by linking voids formed around grain boundary precipitates. In the impact tension, however, transgranular fracture occurs with the resulting excellent reduction in area.View full abstractDownload PDF (1176K) -
Yoichi Ishida, Shukuko Okamoto, Sei Hachisu1977 Volume 41 Issue 11 Pages 1180-1186
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSGrain boundary of polystyrene latex and gold sol crystals were observed by a light microscope. Ordered boundary structures were observed. Brownian motion of the particles in the boundary suggested that the diffusion along the boundary of metals differs largely from that in the lattice. The elementary process of the boundary diffusion was in the form of an “avalanche” involving a chain of particles. Thermally activated boundary phenomena such as diffusion, migration and sliding may be understood as physical quantities produced by the same elementary process.View full abstractDownload PDF (1426K) -
Atsushi Takei, Kazuyoshi Nii1977 Volume 41 Issue 11 Pages 1186-1193
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe Ni-20Cr alloy was oxidized at 1100°C at various oxygen partial pressures, ranging from 10−12 to 10−1 atm, which were controlled by Ar-O2 mixtures. A large difference was observed between the oxidation behavior in a high PO2 (≥10−3 atm) range and that in a low PO2 (≤10−5 atm) range. Therefore, the detailed experiments were carried out in PO2 of 10−1 and 10−5 atm, the former being typical in high PO2 and the latter in low PO2. The weight gain-time curves showed that the growth rate of scale in low PO2 lay between the parabolic and linear law, while that in high PO2 was close to the parabolic law, which indicates that the scale formed in low PO2 is less protective than that in high PO2. It was found, on the other hand, that the oxide scales formed in low PO2 were more adherent to the alloy than those formed in high PO2. In high PO2 a large amount of spalling was observed on cooling even in short time oxidation. The oxide scales formed in low PO2 was uniform in thickness and rather porous, while those formed in high PO2 was non-uniform in thickness and dense. In low PO2 there were found a number of small voids at the oxide-alloy interface, but in high PO2 large voids were found, which suggest the occurence of plastic deformation of oxide and alloy by induced stress in the growing scale. The above difference in oxidation behavior can be ascribed to the difference in growth mechanism of oxide scale due to the high and low PO2.View full abstractDownload PDF (1275K) -
Satoru Yamamoto, Takeshi Yasuda, Yotaro Murakami1977 Volume 41 Issue 11 Pages 1194-1201
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt was confirmed that graphite formed during annealng of white cast iron is nodularized by sulphur addition, and that the nodularizing effect of sulphur depends upon annealing temperature, annealing time, amount of additional sulphur, method of sulphur addition and C contents: (1) The morphology of graphite is changed with increasing annealing time from sphere to irregulr shape. (2) The nodularizing effect of sulphur shows a remarkable dependency upon the annealing temperatures. (3) The graphite-nodularization is accelerated by the increasing amount of additional sulphur. (4) Immersion of stick sulphur into melts is more effective for the nodularization of graphite than the addition of powder sulphur onto surface of melts. (5) In low carbon alloys, graphite is more easily nodularized by a small addition of sulphur.
These results can be explained by the assumption that graphite nodules are formed by the filling up of spherical cavities in the solid with graphite and these spherical cavities were due to sulphur-gas bubbles in the melt on solidification.View full abstractDownload PDF (2641K) -
Susumu Sato, Sh\={o}ju Masaki, Shiro Haruyama1977 Volume 41 Issue 11 Pages 1202-1206
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe stress of a straining copper single crystal in an acidic sulphate solution was found to be reduced by the application of anodic current and to be restored by the cessation of the current. A similar effect was observed by I. R. Kramer on straining single crystals and attributed to the removal of the high dislocation density layer (debris layer) which was formed on the surface as a result of plastic deformation. The stress reduction due to anodic current increased with decreasing strain rate and was greatly exaggerated under the cessation of straining. It was also observed that the magnitude of the stress reduction was proportional to the square of current density and decreased by stirring of solution. Furthermore, the stress reduction effect was also observed by the application of cathodic current. The present results strongly indicate that the stress reduction of straining metal due to anodic dissolution is attributed to the thermal expansion of the specimen by Joul’s heat evolved at the specimen/solution interface.View full abstractDownload PDF (377K) -
1977 Volume 41 Issue 11 Pages 1206
Published: 1977
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPlease see pdf. Wrong:Ba2O3, 532.3 eV Right:Ba2O3, 533.0 eVView full abstractDownload PDF (40K)
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