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Volume 34, Issue 3
Displaying 1-18 of 18 articles from this issue
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Ryô Horiuchi, Keisuke Ishikawa1970 Volume 34 Issue 3 Pages 257-262
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe Hall-Petch relation holds good for the lower yield stress of Al-Mg polycrystalline specimens. The relation between the friction stress σ0 obtained from the above relation and the critical resolved shear stress τc of the single crystal in the wide temperature range can be expressed as
(This article is not displayable. Please see full text pdf.)
The result M≅2 is derived from the difference between the characteristics of edge- and screw-dislocations, the deformation mechanism of the initial yielding and the continuity of material at the grain boundary in Al-Mg alloys.
Therefore, the result is essentially different from those of Sachs, Taylor and Bishop and Hill. The above relation is not always valid in other metals and alloys.View full abstractDownload PDF (2010K) -
Ryô Horiuchi, Keisuke Ishikawa1970 Volume 34 Issue 3 Pages 263-268
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn Al-Mg solid solution alloys, there are found to be an abnormal temperature- and strain rate-dependence of the yield stress in the temperature range between 60° and 200°C. This paper is intended to explain the abnormal phenomenon by the dislocation theory. It is shown that the yield stress comes from the energy dissipation associated with the drift of solute atoms in the stress field of the edge dislocation.
The temperature dependent part of the yield stress may be given by the following equation:
(This article is not displayable. Please see full text pdf.)
where C0 is the effective solute concentration, ρM a moving dislocation density, D the diffusion coefficient, \dotε the strain rate and A a constant.
As a result of the analisis, the effective solute concentration is estimated to be equal to the concentration of solute-vacancy pairs, and the drift of the pairs is of a short range.
This model can be applied not only to Al-Mg alloys but also to many other alloys which have a strong interaction between a dislocation and a solute atom.View full abstractDownload PDF (1540K) -
Genjiro Mima, Tomio Minami, Junichi Sato1970 Volume 34 Issue 3 Pages 268-273
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo know the influence of grain boundaries on the structure and hardness of cold-drawn aluminum bi-crystals, the present study was performed on an aluminum bi-crystal bar which was prepared from a 99.999% purity aluminum ingot by Bridgeman’s method. Specimens were cold-drawn successively to about 98%. Shape, structure and hardness changes were investigated at various working degrees. The main experimental results obtained were as follows: Work-hardening and structure changes depend on the orientation of grains in the cold-drawn specimen. Softening of grains which depends on orientations occurs during cold-drawing. The new grain growth is different from that of the primary recrystallization. The new grains are formed the grain boundary of deformation bands and at the grain boundary of the bi-crystal.View full abstractDownload PDF (2659K) -
Mayumi Someno, Hiroshi Saito1970 Volume 34 Issue 3 Pages 273-279
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInternal friction at the frequency of 70 c/s on hydrogenated Ti-3.25%Mn and Ti-5.95%Mn alloys have been measured. A relaxation peak was observed in the temperature range −160° to −190°C. The peak temperature shifts by the heat treatment of the alloys. The peak value is proportional to the hydrogen concentration and the peak value for Ti-5.95%Mn alloy is higher than that of Ti-3.25%Mn alloy for equivalent hydrogen concentrations. The mechanism of this peak formation is suggested to be due to stress-induced diffusion of hydrogen in the beta-phase (bcc structure) of the Ti-Mn alloys. The activation energy associated with this peak is roughly suggested to be 5 kcal per g-atom. The experimental curve is much broader than the theoretical one, implying either a distribution of relaxation times or more than two relaxation phenomena.View full abstractDownload PDF (1771K) -
Toru Watanabe, Yuichi Sato, Renpei Yoda1970 Volume 34 Issue 3 Pages 279-285
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMassive eutectic γ′ and fine γ′ phases were precipitated in the cast Ni-base No. 64 alloy, but, when aged at 900°C, the precipitation of the σ phase occurr in this alloy. Furthermore, M3B2 and TiC phases precipitated by the addition of boron and carbon, respectively, and the TiC phase was partially decomposed to M23C6 by aging at 900°C. Even by the addition of about 1% carbide forming elements, such as vanadium, niobium and zirconium, mono-carbides of vanadium and niobium could not be recognized. Discontinuous precipitation of the η phase started in low-aluminum No. 64 allloy when aged at 900°C, and the grain in this alloy was covered with this precipitant after 50-hr aging. The γ′ and η phases were extracted effectively by electrolysis with 20%H3PO4 aqua solution, and other phases with 10%HCl methanol solution.View full abstractDownload PDF (2339K) -
Masao Izumiyama, Masayuki Tsuchiya, Yûnoshin Imai1970 Volume 34 Issue 3 Pages 286-291
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of cooling rate on A3 transformation temperatures of a few pure irons, iron-low carbon alloys and iron-nickel alloys have been measured at cooling rates between 100°C/sec and 60000°C/sec by using a gas quench apparatus. A3 transformation temperature of iron containing less than 0.003 wt%C falls gradually with the increase in cooling rate and continuously approaches a fixed temperature (maximum supercooled A3), but in the iron containing more than 0.006 wt%C that temperature falls discontinuously to the Ms temperature at a cooling rate of about 20000°C/sec. Maximum supercooled A3 temperatures of these irons are affected seriously by a very small amount of carbon below 0.005 wt%C and descend remarkably from about 720°C at 0.001 wt%C to about 650°C at 0.003 wt%C with increasing carbon content. A3 transformation temperatures of iron-nickel alloys descend with increasing cooling rate and fall discontinuously by about 100°C at a certain cooling rate which depends on the nickel concentration. The drop of the transformation temperatures is independent of further cooling rate. The critical cooling rate decreases from about 25000°C/sec at 1%Ni to about 2000°C/sec at 20%Ni. The Ms temperatures of these alloys are in agreement at higher nickel concentrations with those reported previously, but are displaced to a lower temperature side at lower nickel concentrations.View full abstractDownload PDF (1906K) -
Masao Izumiyama, Masayuki Tsuchiya, Yûnoshin Imai1970 Volume 34 Issue 3 Pages 291-295
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe cooling rate dependence of A3 transformation and maximum supercooled A3 temperatures have been investigated on eleven kinds of iron binary alloys by using a rapid cooling apparatus. Maximum supercooled A3 temperatures of Fe-Mn alloys show good agreement at higher manganese concentrations with those reported previously but are displaced to lower temperatures at lower manganese concentrations. Extraporation of the resulting data into zero content of the alloying element leads to the maximum supercooled A3 temperature of about 720°C for pure iron. The maximum supercooled A3 temperatures of Fe-Cr, Fe-Cu and Fe-Mo alloys descend with increasing content of each alloying element and those of Fe-Al, Fe-Ti and Fe-V alloys ascend. In Fe-Co alloys, their maximum supercooled A3 temperature ascend up to about 40%Co and are then lowered. Si, W and Nb have little effects on the maximum supercooled A3 temperature of iron. Some of the alloying elements have a different effect on the change of A3 transformation temperature of iron with concentrations in the non-equilibrium condition and in the equilibrium condition.View full abstractDownload PDF (1351K) -
Hideyuki Itô, Kyôji Tachikawa1970 Volume 34 Issue 3 Pages 296-302
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn eddy current method for detecting flaws in fine wires of Nb-Zr alloy and the influence of the flaws on the superconducting critical current Ic of the wires were investigated. The 0.25 mmφ wire was sent continuously through a small pick-up coil. The flaws on the wire, cracks and irregularly deformed cross sections can be detected sensitively by the impedance change of the coil oscillated at 300 kHz. The relation between the depth of artificially introduced cracks and the intensity of the signals was studied.
For artificial cracks, a magnetic field angular dependence of Ic was found. Ic shows maxima and minima when the applied field is parallel and perpendicular to a single crack, respectively. The anisotropy of Ic disappears after annealing at 785°C and seems to be due to an anisotropy of the sub-structure along the crack. Natural flaws decrease Ic from 10 to 50% and make the field angular dependence of Ic complicated. This seems to be due to the overlapping influence of several cracks in the natural flaw part. The decrease of Ic caused by the flaws can be recovered considerably by copper-coating.View full abstractDownload PDF (2449K) -
Kô Soeno, Masatoshi Tuchiya1970 Volume 34 Issue 3 Pages 302-307
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSNitrogen damping peaks of alpha-iron containing 1 atomic pct copper were measured with the transverse vibration of about 550 c/s, and with the torsional vibration of about 2 and 5 c/s. Besides the usual nitrogen peak of unalloyed iron, an additional peak was observed on the higher temperature side. Activation energy of the high temperature peak was determined as 19.2 kcal/mol from the peak shift. The origin of the high temperature peak is attributed to the stress-induced diffusion of nitrogen atom in the vicinity of copper atom. The half-width of the high temperature peak is broader than that of a peak having a single relaxation time. The broadening, which was not changed even in the precipitation of copper, is explained by allowing the relaxation time to have an appropriate error-functional distribution. The relation between the peak height and the nitrogen content in solution was disscused. Also the effect of copper on the solubility of nitrogen in solution equilibrated with nitride, Fe8N, was investigated. It was found that the solubility was increased with the addition of copper.View full abstractDownload PDF (1637K) -
Taro Takeyama, Heishichiro Takahashi1970 Volume 34 Issue 3 Pages 307-312
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSRows of prismatic dislocation loops in tantalum were observed by means of thin-film transmission electron microscopy. These loops generated from precipitates in the test piece furnace-cooled from 1200°C and showed to lie in the ⟨111⟩ directions. It is considered that these loops are produced by the volume difference between the matrix and precipitates and that the difference results from rapid growth of the precipitates during cooling. These rows consist of dislocation loops, thus, showing a small tapering with a distance from each precipitate. These dislocation loops are not observed in the as-quenched and aged specimen. The amount of the critical resolved shear stress to move the loop seems to be consistent with the theory of Bullough and Newman. The value agrees fairly well with that for slip.View full abstractDownload PDF (1521K) -
Katsuhisa Sugimoto, Yoshinobu Sawada, Susumu Morioka1970 Volume 34 Issue 3 Pages 312-318
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn experimental study has been carried out so as to investigate the effects of alloying elements on the pitting corrosion of aluminium. Twenty two kinds of binary aluminium alloys were prepared as the specimens and their electrochemical properties were measured in 1 N-NaCl solution.
The results obtained were summarized as follows:
(1) The shift of the pitting potential of aluminium is obviously observed in the alloys containing more than 0.6% alloying elements. Pitting potentials of binary aluminium alloys with 5∼10% alloying elements are arranged in order from noble to less noble:
Al-Cu>Al-Ni>Al-Fe, Al-Si>Al-V>Al-Mn, Al-Cr, Al-B>Al-Zr>Al-Ti>Al-Mg>Al-Be.
(2) Effects of alloying elements on the pitting dissolution rate are arranged in the decreasing order of activity: Fe>Mg>Mn>Si>Cu. This accords with the order of effects of the alloying elements on the number of pits observed for a given time.
(3) The cathodic polarization in a neutral solution of NaCl is large for the aluminium alloys containing Mn, Mg and Si, but it is very small for the alloys containing Fe and Cu. Since the pitting corrosion in the neutral solution depends upon the cathodic reactions, it is preferable to alloy the elements which makes large the cathodic polarization to increase resistivity against pitting corrosion.View full abstractDownload PDF (2110K) -
Shoji Goto, Shigeyasu Koda1970 Volume 34 Issue 3 Pages 319-326
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDilute solid solution nickel alloys containing aluminium or chromium up to 4 wt% were internally oxidized at temperatures between 900° and 1300°C for various times, and the relation between the diffusion rate of oxygen and the size and distribution of oxide particles in the internally oxidized layer was investigated.
The results obtained are as follows:
(1) In each of the alloys, the diamater and interparticle spacing of dispersed oxide particles increased with increase in temperature, and the density of particles increased with solute content.
(2) The effective diffusion coefficient of oxygen, D0, in the internally oxidized layer increased with increase in solute content, and the concentration dependency of D0 increased with temperature.
(3) The value of D0 increased with increase in the net volume of the highly diffusive region around the oxide particles in the matrix, and decreased with the volume of particles, of which the diffusion rate was extremely low in comparison with that in the matrix. Therefore, the value increased with increasing size of particles up to a critical diamater, R*, after which it decreased and became that of the matrix at another critical diamater, Rmax. Both the values of R* and Rmax decreased with increase in temperature.
(4) Analyzing the relation between D0 and the size and interparticle spacing of particles as a function of temperature and solute content, the diffusion coefficient in the interfacial layer around the particles, D0B, was found to be greater than that in the matrix D0L at 900°∼1300°C. Activation energies for D0L and D0B were analogous to the values for self-diffusion in the matrix and at large angle grain boundaries in nickel, respectively.
(5) At higher temperatures the effect of the solute content on D0 was small. This seemed to be attributable to the growth of particles, decrease in particle density, and decrease in the particle effect on D0 with increase in temperature.View full abstractDownload PDF (2347K) -
Shoji Goto, Shigeyasu Koda1970 Volume 34 Issue 3 Pages 326-332
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDilute solid solution nickel alloys containing up to 4 wt% aluminium or chromium were oxidized for various times at temperatures between 900° and 1300°C in air in order to investigate the growth rate of internal and external oxidation layers formed simultaneously.
The results obtained are as follows:
(1) Both internal and external oxidation layers grow in proportion to the square root of time. The internal oxidation layer increased and the external decreased with increasing solute content.
(2) From measurement of the thickness of internal oxidation layer and the rate of internal oxidation from the original surface, the diffusion coefficient of oxygen, D0, in the internal oxidation layer was found to increase with the solute content.
(3) The growth rate constant of the external oxidation layer, Kex, increased with the solute content. The logarithmic plot of Kex against the reciprocal of the absolute temperature showed a pronounced kink at about 1100°C and the effect of the solute content for Kex became maximum at about 1100°C. Some consideration was made on it.
(4) The internal oxidized layer was formed in preference to the external oxidized layer with increasing temperature and decreasing solute content.View full abstractDownload PDF (2272K) -
Hitoshi Nakae, Kôsuke Tagashira, Tsuyoshi Matsumidori1970 Volume 34 Issue 3 Pages 333-337
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMuch works have been done on the growth of single crystal of 3.25%Si-Fe alloy by strain-anneal method. In the present work, the growing front of single crystal was observed for investigating the mechanism of grain growth in the 3.25%Si-Fe alloy specimens with three different sulphur contents. It appeared that the matrix grains with convex boundaries to the single crystal were not easily consumed in the crystal. Their orientation differences relative to the single crystal were measured.
It was concluded that in the alloy containing a large amount of sulphur, the grains having higher misfit angles to the single crystal were more difficult to be consumed than those having lower misfit angles, whereas in the higher purity alloy, the situation was reversed. The results are in accordance with the consideration from the dislocation theory.
A further extension of the results to the secondary recrystallization in a oriented silicon iron sheet was also discussed.View full abstractDownload PDF (919K) -
Toshiyuki Suzuki1970 Volume 34 Issue 3 Pages 337-343
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe relation between the Ni content and the hardening capability of Ni-rich TiNi compounds, and the effect of heat treatment on the mechanical properties of a TiNi compound containing 54.7 at%Ni have been investigated. TiNi compounds containing more than 52 at%Ni show a considerable increase in hardness by quenching, and the maximum hardness is attained at about 54.5 at%Ni. According to the phase diagrams which are considered to be most reliable, the composition from which the hardening effect appears corresponds to the composition of the boundary between the TiNi phase and the TiNi+TiNi3 phase at lower temperatures and the composition at which the maximum value of hardness is obtained coincides with the composition of the same boundary at quenching temperature. This fact seems to suggest that the hardening capability in the Ni-rich TiNi compound is related to the existence of excess point defects which are introduced by deviation from the stoichiometric TiNi composition at the quenching temperature. The TiNi compound containing 54.7 at%Ni is hardened by quenching from temperatures above 600°C, and the hardness increases with increasing temperature. When the TiNi is quenched from 1100°C into water, the Vickers hardness of about 700 is obtained. The hardness of the quench-hardened TiNi decreases with annealing time. However, no hardening effect due to the precipitation of TiNi3 is observed. The tensile strength of the TiNi is 80 kg/mm2 in the annealed state and 100 kg/mm2 when annealed at a relatively high temperature after quenching. Although the Young’s modulus of the TiNi in the annealing state is anomalously low as compared with the values of the constituent metals, quenching from 1000°C gives a nearly 25% increase of the value.View full abstractDownload PDF (1789K) -
Kyuya Nagasaki, Shiro Haruyama, Masami Kaneko, Isao Ito1970 Volume 34 Issue 3 Pages 343-347
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn previous work, it was found that the weight loss-time relation shifted from 1/2 to 1 power of time with increasing zinc content in α-brasses. This behavior was explained with reference to the change of metallurgical structure, that is, the development of an abnormal dezincified layer.
In the present work, the effects of additives on the dezincification of α-brasses were investigated. The experiments were carried out at 800°C in vacuum (c.a. 10−5 mmHg). Ag of group 1, Al and Ga of 3, Si, Ge and Sn of group 4, Cr of group 6, Mn of group 7, and Fe, Co and Ni of group 8 in the periodic table were selected as the additive elements.
As a result, it was found that Si, Ge, Sn(4), Cr(6), and Mn(7) enhanced the rate of dezincification, while Ag(1), Al, Ga(3) and Fe, Co, Ni(8) had no effects. The concentration profiles were classified into three types; the (Si, Ge, Sn) type, the (Al, Ga, Cr, Mn) type, and the (Ag, Fe, Co, Ni) type. The grades of effects were considered with reference to those types. The weight loss was proportional to time for all the specimens, in agreement with that for 30 wt%Zn α-brass.View full abstractDownload PDF (1847K) -
Natsuo Yukawa, Moritaka Hida, Toru Imura, Masao Kawamura1970 Volume 34 Issue 3 Pages 348-355
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStructures of Cr-Ni, Cr-Fe and Cr-Co alloy particles prepared by evaporation in argon gas at low pressure were investigated by means of X-ray and electron diffraction techniques. The results obtained are summerized as follows:
(1) The particles obtained are nearly spherical with the diameter of 100∼1000 Å, having no well-defined crystal habit.
(2) In the high chromium alloys of the three alloy systems, the δ-phase of the A-15 structure is newly confirmed to occur.
The lattice parameters of the δ-phase almost coincide with that of the δ-Cr phase (a0=4.588 Å) reported by Kimoto et al.
(3) In the Cr-Ni system, the σ-phase of the β-uranium structure (D 8b) was confirmed to occur as it has been suggested theoretically.
The lattice parameter almost coincides with those of the σ-phase (in Co-Cr and Cr-Fe systems) reported hitherto.
(4) Tentative phase diagrams of Cr-Ni, Cr-Fe and Cr-Co systems were proposed from the results obtained.View full abstractDownload PDF (1734K) -
Teruo Ohashi, Riei Ichikawa1970 Volume 34 Issue 3 Pages 356-360
Published: 1970
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe structural changes with the addition of Si in the metastable solid solutions of Al-2 wt%Cr alloys which were obtained, as reported previously, by casting them in a chilled copper mold, were studied by means of X-ray lattice parameter measurements, resistmetoric and microscopic methods, etc. With increasing Si content, (a) the minimum cooling rate to produce the cellular dendritic structures of the primarily solidified Al rich α-phase could be lowered and (b) the lattice parameter increased linearly, that is, the supersaturatedly dissolved Cr in the α-phase decreased. It was shown that the mechanical properties of these alloys were improved by ternary eutectics distributed finely in the boundaries of cellular dendrites. The decomposition temperature of these alloys was about 200°C but little affected by the Si content.View full abstractDownload PDF (1947K)
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