All issues
Volume 37, Issue 10
Displaying 1-16 of 16 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kokuya Iwamura1973 Volume 37 Issue 10 Pages 1049-1056
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new expression of the mono-vacancy concentration in a crystal is proposed in this paper. The expression which can be derived from the basis of statistical mechanics is written in the form C1=[α1exp(ε1−μ1)⁄kT+a1]−1, where C1 is the mono-vacancy concentration, ε1 and μ1 are the formation energy of mono-vacancy at 0°K and its chemical potential, respectively, α1 is a constant and a1 is a parameter. The concentration of substitutional mon-impurities is also given in the same form. However, there is the essential difference between vacancy and impurity. The chemical potential of the former must be μ1=0 in contrast to μ1\leavevmode\hboxto 0pt=\llap\ 0 for the latter.
The expression may be understood analogically in relation to the Fermi-Dirac distribution function. The expression makes it clear that the usual expression C1=γexp[−Elf⁄kT] is applicable at low temperatures, but does not hold at high temperatures approaching the melting point. Applications of the expression are made to examine the exprimental results on thermal expansions of gold and aluminium by Simmons and Balluffi, and the difference between the formation energy of mono-vacancy of aluminium obtained from thermal expansion and that from position annihilation is also discussed.View full abstractDownload PDF (711K) -
Takefumi Horiuchi, Yoshiyuki Monju, Isamu Tatara, Nobuyuki Nagai1973 Volume 37 Issue 10 Pages 1057-1064
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of cold work on the rates of the β phase decomposition in the Ti-30 Nb-30 Zr-7 Ta superconducting alloy was investigated. T.T.T. diagrams for the cold worked specimen were determined from the changes in electrical resistivity at liquid nitrogen temperature, inicro Vickers hardness number measurement and the lattice constants determined by the X-ray powder method.
The main results are as follows:
(1) The α phase precipitation occurs by ageing at temperatures lower than 550°C and the transformation of the β phase to the β′+β″ phase at temperatures higher than 550°C. At 550°C, the β phase decomposition into the α+β′+β″ phase was found.
(2) The rates of the α phase precipitation were accelerated by cold work. On the other hand, the effect of cold work on the rates of the β phase decomposition into the β′+β″ phase was small.
(3) The ω phase precipitation was found between 450 and 700°C. The c⁄a of the ω phase is 0.620 at 550°C and 0.627 at 650°C.
(4) Electrical resistivity was decreased by the α phase precipitation but remained almost unchanged in the region of the β′+β″ phase and the α+β′+β″ phase.
(5) In the region of the β′+β″ phase and α+β′+β″ phase, the micro Vickers hardness number decreased with ageing time, but it was increased in the α phase precipitation region and then decreased by over ageing.View full abstractDownload PDF (867K) -
Hirohisa Kokon, Pongun Son, Masanobu Miyake, Tadao Sano1973 Volume 37 Issue 10 Pages 1065-1068
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSelf-diffusion coefficients of carbon in a carbide of niobium has been measured in the temperature range 1800∼2200°C, using radioactive tracer techniques. The self-diffusion coefficients can be expressed by
(This article is not displayable. Please see full text pdf.)
Comparing the present results with the chemical diffusivities obtained by the carbide layer growth method, it is shown that the relations between self-diffusivities and chemical diffusivities of carbon in the carbides of transition metals can be explained qualitatively on the assumption that carbon diffuses in the carbide by a vacancy mechanism.View full abstractDownload PDF (353K) -
Shozo Yoshioka, Mitsuo Mera, Kenji Morii1973 Volume 37 Issue 10 Pages 1068-1075
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDeformation behaviours of copper bicrystals during rolling which had been studied in a previous report were analyzed by means of finite deformation theory.
For the (101)[\bar121] and (211)[\bar111] grains, the observed shape changes in the plane of rolling, orientation changes and active slip systems were explained by this analysis: The suppression of the shear in a rolling plane of the (101)[\bar121] grain is attributed to the operation of the slip systems D2 and D5 with the amounts of shear \simeq0.3 times as much as that on the main slip systems B5 and C\bar2. The (101)[\bar121] orientation is stabilized when each pair of slip systems B5, C\bar2 and D2, D5 operates equally. In the (211)[\bar111] grain, the unequal operation of C\bar2 and D2 systems causes the shear in the rolling plane. This effect also brings about the fluctuation of orientation around the rolling direction.
The deformation behaviours of the (513)[\bar121] grain can hardly be explained by this analysis in which macroscopic homogeneous deformation has been assumed. According to this analysis, it is expected that stabilization of the orientation and suppression of the shear in the plane of rolling in the (513)[\bar121] grain should be is due to activation of the slip system D2. Nevertheless, no traces of this slip system were detected in the slip line observation using replica electron microscopy.View full abstractDownload PDF (767K) -
Kenzaburo Kumada, Akinobu Okamoto1973 Volume 37 Issue 10 Pages 1076-1081
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA phenomenon has been observed that the magnetic transformation temperature of high chromium-iron alloys aged at around 600°C shifts to a higher temperature than that of the as-solution treated alloy. To clarify the relation of this phenomenon with the 475°C embrittlement, the changes of the magnetic transformation temperature, hardness and microstracture of high-purity high chromium-iron alloys (47 wt% Cr, 52 wt% Cr and 57 wt% Cr) on aging at 475, 550, 600, 650 and 700°C were studied. The results obtained are as follows:
(1) The magnetic transformation temperature of iron-chromium alloy on aging at 600 and 650°C shifts to a higher temperature than that of the as-solution treated alloy.
(2) The reason for the fact (1) is not directly related to the precipitation and resolution of chromium compounds such as chromium carbide and nitride, and 475°C embrittlement (or a spinodal decomposition).
(3) The anomaly that suggest the spinodal decomposition was observed in thermal magnetic analysis curves in alloys aged at 550°C for 50 hr and more.View full abstractDownload PDF (1147K) -
Hajime Suto, Yutaka Tomono1973 Volume 37 Issue 10 Pages 1082-1087
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is well known that the stacking fault energy is one of the most important strengthening factors affecting the high temperature strength of FCC metals and alloys. In this paper, in order to obtain some knowledge of the temperature dependence of the stacking fault energy of the matrix in superalloys, the hot-stage studies of dislocation nodes in Fe-Cr-Ni and Co-Ni-Cr(-Mo) alloys were carried out by means of 500 kV and 200 kV electron microscopes. The results obtained are as follows: (1) The most important mechanism controlling the irreversibility of the shape of dislocation nodes during thermal cycling was considered to depend on some phenomena in which the diffusion of solute atoms took part. (2) The width of extended dislocation node was distinctly contracted by heating over about 500°C. (3) It is considered that the abnormally extended dislocation nodes observed in quenched specimens are introduced by quenching stress.View full abstractDownload PDF (1292K) -
Tetsuji Noda, Kiyokatsu Kudo, Norio Sato1973 Volume 37 Issue 10 Pages 1088-1093
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe anodic passivation films formed on iron in sodium phosphate, borate and hydroxide solutions at various pH values have been investigated by means of ellipsometry, thermogravimetry, and electrochemical analysis.
Ellipsometric measurements reveal that the film consists of an inner layer of γ-Fe2O3 and an outer layer of hydrous ferric oxide.
The thickness of the inner layer increases linearly with rising passivation potential, and the potential at which the inner layer vanishes is found to agree well with the equilibrium potential of γ-Fe2O3 formation on iron in the pH range from 1 to 12. The outer layer appears to depend on the pH and anion of the solution but its thickness is almost independent of the potential at which the film is formed. These results indicate that the overvoltage of film formation occurs in the inner layer irrespective of the solution pH.
At constant overvoltage, therefore, the inner layer thickness is constant independently of the solution pH in neutral and basic solutions where no dissolution of the film occurs. In acidic solutions, however, the inner layer becomes thin as the solution acidity increases because of increase of the rate of film dissolution. The outer layer thickness decreases with decreasing solution pH in the basic and neutral pH range and is negligibly small in acidic solution.
It is also shown that the more basic solution results in the more amount of water diffusing into the outer layer.
A film model is proposed in which the outer layer is affected by the solution pH, while the inner layer is determined only by the overvoltage of film formation.View full abstractDownload PDF (477K) -
Kazuo Nagata, Seiichi Nishikawa1973 Volume 37 Issue 10 Pages 1094-1100
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe precipitation and reversion processes of Cu-0.28 wt% Cr alloys were determined from the electrical resistivity change during step annealing of as-quenched and pre-aged samples.
The results obtained are summarized as follows:
(1) The precipitation process is separated into two parts by the reversion process taking place in the intermediate temperature region.
(2) The activation energies of the two precipitation processes were nearly equal and 1.45∼1.42 eV.
(3) The reversion of low temperature precipitates is not complete but partial.
(4) The apparent amount of reversion decreases rapidly as the pre-ageing temperature rises. At a constant pre-ageing temperature, it increases first with ageing time and then decreases after passing through its maximum point.
(5) In the case of high temperature pre-ageing for a short time, such as at 500°C and 600°C for 2 min, the reversion of low temperature precipitates is observed.
(6) The activation energy obtained from the isothermal reversion curves is about 1.83 eV, and its process seems to be described by the first order equation.View full abstractDownload PDF (638K) -
Masayuki Hasaka, Kensuke Oki, Tetsuo Eguchi1973 Volume 37 Issue 10 Pages 1101-1107
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe vacancy concentration, jump frequency of atoms and self-diffusion coefficient in Fe-Al alloys with B2 and DO3 ordering have been investigated by means of the Bragg-Williams approximation in which the interactions between atoms in the first and second nearest neighbors are taken into consideration. As the ordering proceeds, the vacancy concentration on the sublattice which favors the occupation by Fe atoms increases with the Al concentration, whereas the one which favors Al atoms decreases. The jump frequency of atoms to a neighboring vacant site depends not only upon the composition and the degrees of order of the alloy but also upon the sort of atoms and the sublattices between which the jump will take place. The self-diffusion coefficients for Fe and Al atoms are obtained in terms of those jump frequencies, and the temperature dependence of the coefficients is in qualitative agreement with the available experimental data.View full abstractDownload PDF (512K) -
Shoji Goto, Shigeyasu Koda, Shotaro Morozumi1973 Volume 37 Issue 10 Pages 1108-1114
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSamples of some Zn-Ti hyper-eutectic alloys have been unidirectionally solidified at speeds up to 150 cm/hr. The growth rates of eutectics, temperature gradients in the liquid phase during the growth, eutectic structures and solute segregation in unidirectionally solidified specimens were investigated to determine the mechanism of nucleation and growth of lamellar-or rod-eutectics. The results obtained are as follows. (1) For higher solidification rates and lower solute concentrations, the density of the TiZn15 rod, which was formed as a part of the eutectic in the nucleation stage increased. (2) During the progressive solidification stage the solidification rate increased, but the temperature gradient in the liquide phase decreased. (3) Density of the rectangular eutectic TiZn15 rod increased by branching during the growth period due to the increase of the rate of growth in the progressive solidication stage. (4) For lower solidification rates, the Zn-Ti alloys exhibited lamellar eutectic-structures for a wide range of liquid compositions. This effect is due to the steep temperature gradient in the liquid phase and a small degree of constitutional supercooling at the liquid-solid interface. However, for higher solidification rates, the structure formed, eutectic or eutectic plus dendrite, depended on the solidification rates and liquid compositions due to the growth kinetics of the dendrite and eutectic structures in a given supercooled liquid phase. (5) During the growth of eutectics with TiZn15 dendrites in higher concentration alloys, large solute segregation along the growth direction was revealed. However, during the growth of fully rod eutectics, there was no segregation even when the rod density increased by branching. (6) The λ∝R−1⁄2 relationship proposed in the Jackson model remained valid even for hyper-eutectic-composition alloys, and some considerations were made about this phenomenon.View full abstractDownload PDF (917K) -
Hideo Abe, Sumio Yamada1973 Volume 37 Issue 10 Pages 1115-1120
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn a high-purity electrolytic nickel cold rolled to 72.5% reduction, the cube texture developes as the secondary recrystallization texture. The major part of the primary recrystallization texture is nearly random except a weak preferred orientation of (100)[001]. The results can be rationally interpreted on the basis of the ‘oriented growth’ theory. It is concluded that the nearly random texture after primary recrystallization is due to the ‘random nucleation’ and that the cube texture developes by the ‘selective growth’ of large primaries with (100)[001] orientation.View full abstractDownload PDF (868K) -
Tetsuya Hirouchi, Kuo-Shung Liu, Yotaro Murakami1973 Volume 37 Issue 10 Pages 1120-1127
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe size of a platelike G.P.zone in an Al-4%Cu alloy has been more successfully determined by the measurement of the X-ray diffuse scattering intensity distribution around (110) in the reciprocal lattice, than the small angle scattering photographic method reported previously by the present authors.
The formation, growth and reversion of G.P.zones have been investigated by this method together with the measurement of electrical resistivity.
G.P.(1) zones of the specimens quenched from 450°C grow with ageing time at the early stage of isothermal ageing at 40, 80 and 110°C, and the zone diameters reach constant values of approximately 58, 75 and 85 Å respectively. However, the zone radius of the specimen aged at 135°C stayed constant at a value of about 85 Å, but increased again 300 min after the subsequent ageing. This was probably due to the formation of G.P.(2) zones. The upper temperature limit for the formation of G.P.zones was determined to be approximately 200°C, and no G.P.zones were detected at temperatures above 205°C by use of X-ray analysis. The value of electrical resistivity of the reverted specimens was found to be always 5% lower than that of the as-quenched specimens. This should be explained in terms of the exsistence of solute clusters in the as-quenched specimens.View full abstractDownload PDF (693K) -
Han-Ryong Pak, Toshio Saburi, Soji Nenno1973 Volume 37 Issue 10 Pages 1128-1134
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to make clear the nature of transformation from the high-temperature phase of the DO3 type ordered structure into the low-temperature β phase of the DO19 type ordered structure in Ni3Sn alloy, the microstructures and crystal structures of transformation products obtained by quenching at several cooling rates were investigated by means of metallographic, electron-microscopic and X-ray diffraction techniques.
The results obtained are summarized as follows:
(1) A martensitic transformation occurs when quenched rapidly at a rate of about 2000°C/sec and the martensite (γ′) has an ordered structure of the β-Cu3Ti type. There are many internal twins within the γ′ martensite.
(2) When quenched at rates less than about 200°C/sec, the high-temperature phase shows a massive-transformation into the β phase.
(3) The massive β phase in the Ni3Sn alloy is a stable phase.
(4) This massive transformation occurs from one ordered phase to another ordered phase.
(5) In the massive β phase obtained by quenching at a rate of about 200°C/sec there are a number of planar defects on the {10\bar10} type plane (prism plane) and the {0001} type plane (basal plane).View full abstractDownload PDF (1252K) -
Shigenori Hori, Shigeoki Saji, Tomio Kobayashi1973 Volume 37 Issue 10 Pages 1134-1138
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHardness and structural changes during aging of an Al-0.22% Zr alloy at 350, 400 and 450°C for 8∼10 hr were studied. Hardening curves at 350°C aging show a monotonous increase with increasing time and after about 6×103 hr, a pronounced peak appeared. However, at higher temperature aging, no appreciable increase of hardness was observed.
In the initial stages of aging, rod-shaped precipitates were formed behind moving grain boundaries. Growth of these precipitates due to a grain boundary reaction was retarded by development of precipitation within the grains. Plate-like precipitates were sparsely observed within grains. These precipitates and the precipitates due to the grain boundary reaction have no essential role in the age hardening of this alloy.
On the other hand, coherent spherical particles were also observed within grains. It was found that the growth of the spherical precipitate was diffusion controlled. From the growth rate, the activation energy for diffusion of Zr in Al has been estimated to about 50 kcal/mol. It was thought that the coherent particles are the predominant factors for the increment of hardness during aging. Growth of the spherical precipitates by prolonged aging accompanied a loss of coherency and occurred prefferentially along a definite matrix direction, resulting in the formation of protrusions.View full abstractDownload PDF (968K) -
Yoshiaki Umetsu, Masami Kawada, Eiji Nakamura, Tatsuhiko Ejima1973 Volume 37 Issue 10 Pages 1139-1145
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe surface tensions of binary PbCl2-ZnCl2 melts have been measured by the maximum bubble method in the temperature range up to about 200°C above the liquidus. The changes of liquid structure or the constituent ionic species have also been estimated on the basis of the present results and the data on the density, electric conductivity and viscosity reported in the previous papers. The results are summarized as follows:
(1) At each composition the surface tension shows an approximately linear decrement with rising temperature. The surface tension of molten ZnCl2 has a considerably low value and a low temperature coefficient as compared with other chlorides. This seems to indicate the associating property as previously suggested by the authors.
(2) There are inflection points at about 50 mol% PbCl2 in the plots of surface tension, temperature coefficient of surface tension and surface enthalpy per unit area against composition. It is to be noted that dσ⁄dT corresponding to the surface entropy per unit area, varies only slightly with PbCl2 content in the composition range less than 50 mol% PbCl2. This is quite similar to the trends which were previously observed in the transport properties of this binary system such as electric conductivity and viscous flow.
(3) The results obtained in this work also supports that the estimation suggested in the previous paper for changes in constituent ionic species with composition of this binary liquid system is adequate one.View full abstractDownload PDF (573K) -
1973 Volume 37 Issue 10 Pages 1145
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPlease see pdf. Wrong:Cu-Sb Right:Cu-GaView full abstractDownload PDF (121K)
- |<
- <
- 1
- >
- >|