All issues
Volume 37, Issue 7
Displaying 1-20 of 20 articles from this issue
- |<
- <
- 1
- >
- >|
-
Yuzo Oda, Koichi Nakajima1973 Volume 37 Issue 7 Pages 673-677
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new method for the simultaneous determination of thin film thickness and its chemical composition is proposed. This method is characterized by the determination of them from the ratio of the intensity of characteristic radiation emitted from the constituent element to the intensity of the same characteristic radiation emitted from the pure element under the same condition of electron bomberdment.
It is found that the results obtained to date through the use of the present method have been fairly good with the accuracy of the order of 10 per cent.View full abstractDownload PDF (396K) -
Goro Omori, Shigeru Matsuo, Hiroshi Asada1973 Volume 37 Issue 7 Pages 677-682
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe precipitation process in Mg-1.3 wt% Ce alloy was studied by means of electrical resistivity measurement and electron microscopy. On isochronal annealing of the alloy, the electrical resistivity decreased gradually up to about 200°C, followed by an abrupt decrease between 200∼325°C. This abrupt decrease was attributed to the precipitation of an intermediate phase. On further heating, the electrical resistivity increased steadily, but the increase halted temporarily at 450∼500°C. At this stage, the precipitation of the equilibrium phase was observed.
On isothermal annealing in a temperature range of 100∼150°C, the electrical resistivity decreased in two stages. Following Johnson-Mehl equation, the values of 2/3 and 1.0 were obtained as the time exponents, n, for the first and the second stage, respectively. Using the isothermal curves of resistivity change, estimations of apparent activation energies for the above two stages were also made. For both stages, the activation energy increased as the precipitation proceeded. From a microstructural examination, it was shown that the resistivity decrease in the first stage was associated with the precipitation of the equilibrium phase on dislocations and grain boundaries, and that in the second stage with the precipitation within grains.View full abstractDownload PDF (750K) -
Teruyoshi Umemura, Tatsuo Tejima1973 Volume 37 Issue 7 Pages 683-692
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe purpose of the present paper is to investigate the solidification process of alloy castings by numerical calculations, using the previously derived equations on the model that the dispersed crystals grow in the melt. Al-low Cu plates were taken as the examples. An explicit finite difference method in which the first approximations are obtained regarding an equilibrium solidification process and corrected to the non-equilibrium values has been introduced.
The influence of the factors of the casting operation was investigated, and it has been made clear that the increase of copper addition, the decrease of thickness of casting and the decrease of heat transfer coefficient at the mold-casting interface make a flat distribution of solids in a casting during solidification, while the increases of pouring temperature and preheat temperature of the mold have little influence on the distribution of solids but delay the time of solidification. The macrosegregations due to diffusion were too little to be confirmed experimentally. The calculated cooling curves have the same behaviors as those experimentally obtained, but the details of the curves do not agree with each other because of unknown changes of the heat tranfer coefficients during solidification. The solidus and liquidus concentrations have always higher aluminum values than the equilibrium, and the deviations from the equilibrium rapidly decrease with the progression of solidification. The variation of number or shapes of growing crystals hardly affects the calculated results.View full abstractDownload PDF (808K) -
Akira Watanabe, Goro Ohira1973 Volume 37 Issue 7 Pages 692-696
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA voltge-dependent maximum value is observed in the measured X-ray intensities of a element of low Z under the condition of constant specimen current in electron probe analysis. In order to explain this phenomenon, the voltages giving the maximum intensity have been measured for specimens containing the elements ranging from B to Mg with a variety of mass absorption coefficients. And the variation of the depth distribution of OKα with voltage has been estimated as an example of X-rays of low Z from the result of CuKα calculated by Shimizu, Murata and Shinoda by using the Thomson-Whiddington energy loss law and the equation for the ionization cross section of the K shell derived by Green and Cosslett.
It is found that the voltage giving the maximum intensity is propotional to −log(μ⁄ρ) and the maximum value of the depth distribution immediately below observed specimen surface in case of low Z increases with decreasing voltage.
The voltage dependence of the measured X-ray intensity from elements of low Z is well explained by the above results.View full abstractDownload PDF (420K) -
Akira Watanabe, Goro Ohira1973 Volume 37 Issue 7 Pages 697-702
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA voltage-dependent maximum value is observed in the measured intensities of a long wavelength characteristic X-ray under the condition of constant specimen current in electron probe analysis. This voltage giving the maximum intensity VG is almost independent of the mean atomic number of a specimen but dependent on the logarithmic value of the mass absorption coefficient (m.a.c.) of the specimen alone. In the case of the OKα, the relation between the VGO values for a X-ray emergence angle of 52.5° and the m.a.c. of the light element oxides calculated with Henke’s values is expressed by the following equation:
(This article is not displayable. Please see full text pdf.)
VGO values have been determined with an accuracy of 0.5 kV on about fifty oxides, of which each has a single metal constituent of elements ranging from Be to U except for special cases. The VGO values vary from 5 kV in V2O5 to 19.5 kV in Cr2O3. The m.a.c. for the OKα have been estimated by substituting the VGO values into the above-mentioned equation.
Some of the estimated m.a.c. in the cases where the wavelength of the OKα agrees with that of a complex absorption edge of an absorber element, are given as follows:
(This article is not displayable. Please see full text pdf.)View full abstractDownload PDF (524K) -
Seiichi Karashima, Nobuyoshi Hirakouchi1973 Volume 37 Issue 7 Pages 703-707
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTemperature (T) dependence of internal friction (Q−1) and shear modulus (G) was examined by an inverted torsion pendulum with about 1 cps for pure copper and Cu-2.5, 5, 10 and 15 at% Al solid solutions. A grain boundary relaxation peak was observed at about 550°C in all the materials. In Cu-15 at% Al solid solution, it was found that Q−1 and G values showed a temperature hysteresis in the temperature range of 400∼750°C where the peak was observed in Q−1-T curves. The hysteresis was particularly remarkable on the specimens with small grain size. Although the origin of this interesting phenomenon has not been clarified, it seems that the hysteresis cannot be explained by the interaction between grain boundaries and solute atoms which is not in equilibrium in the course of heating and cooling.View full abstractDownload PDF (401K) -
Masatoshi Sakamoto, Yûnoshin Imai1973 Volume 37 Issue 7 Pages 708-714
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of Cobalt, Nickel, Molybdenum and Tungsten on the solubility of Fe16N2 in α-iron were studied by an internal friction technique. Aging curves were measured in the temperature range of 100 to 250°C and the solubility of Fe16N2 was obtained by correcting the equiliblium value of Qmax−1 of first stage with an effect of precipitated nitrides.
The solubility of Fe16N2 in α-iron was given by the equation, log[N%]=−1770⁄T+1.88, and the heat of solution of Fe16N2 in α-iron was abut 8900 cal/mol.
Solubilities of Fe16N2 were also determined with iron alloys containing 0.9 and 4.9% Co, 2.0 and 4.7% Ni, 0.6 and 0.9% Mo, and 0.8 and 1.2% W. The addition of Co, Ni, Mo or W increases the solubility of Fe16N2 in α-iron in the order of (α-Fe)<Ni<Co<Mo<W.
The heat of solution of Fe16N2 was decreased by the addition of those elements with a tendency contrary to the effects on solubility.View full abstractDownload PDF (522K) -
Kazumi Shimotori, Kanji Kawaguchi, Masami Miyauchi, Toshiyoshi Tomita1973 Volume 37 Issue 7 Pages 715-724
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHigh Cr, Ni-base alloys seem to have excellent resistivity to ash-corrosion because of their high Cr contents. Their corrosion resistivities were investigated experimentally by means of a contact test with 80 mol% V2O5-20 mol% Na2SO4 mixed salt for 30 hr at 1100°C. Maximum penetrations of the corrosion were also confirmed by metallographic observation of specimens after the contact test. Effects of alloying elements on the ash-corrosion resistivity of the alloys were qualitatively estimated from the weight loss in regard to (a) the effect of Cr on Ni-Cr binary alloys containing 20 to 80 wt% Cr. (b) effects of Al, B, Co, Mn, Mo, Nb, Ta, Ti, V, W and Zr on 40 Cr-Ni alloy, and (c) effects of Al, B, C, Co, Cr, Mo, Ta and Ti on C-Alloy (36 Cr, 1 Al, 1 Ti, 4 Mo, 5 Ta bal. Ni).
The results are sammarized as follows:
(1) The corrosion loss of Ni-Cr binary alloy is rapidly decreased for the composition of more than 40% Cr.
(2) Additions of Al, B, Zr and Ti improve the ash-corrosion resistivity of 40 Cr-Ni alloy. Amoung various alloying elements the effects of B and Zr are outstanding. Additions of Nb and V are deleterious. Intergranular corrosion with S was observed in 40 Cr-Ni, 40 Cr 10 Co-Ni and 40 Cr 5 Mn-Ni alloy.
(3) Similar effects were obtained for C-alloy. The corrosion loss of C-0.1 B alloy, which is a typical high Cr, Ni-base alloy, was 1/3.5 of that of U-500 and 1/5 of that of S-816.
It is important to consider the alloy composition with regard to ash-corrosion resistivity even in high Cr, Ni-base alloy.View full abstractDownload PDF (1414K) -
Masami Onishi, Yoshinori Wakamatsu, Terunori Sasaki1973 Volume 37 Issue 7 Pages 724-730
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe iron-electrodeposited zinc diffusion couples were annealed at temperatures from 240 to 320°C. In the diffusion zone intermetallic compounds appear in the order of the ζ, δ1 and Γ phases. Kirkendall markers exist always at the interface between the ζ phase and Zn. This pronounced Kirkendall effect means that there is a one-sided diffusion of Zn atoms by a vacancy mechanism.
The ζs phase which exists as a single phase in the diffusion zone at the initial annealing stage grows according to a parabolic rate law. The interface concentration of the ζs phase in contact with the iron couple half deviates about 2.4 at% Fe to the Fe side from the boundary concentration on the Fe-rich side of the equilibrium ζ phase or from the stoichiometric composition of FeZn13 (7.1at% Fe). It is suggested that the deviation is caused by the formation of vacancies on the zinc atom sites and the vacancies contribute to the one-sided diffusion of zinc atoms. Dependence of the diffusion coefficients in the ζs phase on temperature is given by the following equation:
(This article is not displayable. Please see full text pdf.)View full abstractDownload PDF (944K) -
Kiyohiko Nohara, Ken-ichi Hirano1973 Volume 37 Issue 7 Pages 731-736
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe residual activity technique was employed to determine the impurity diffusion coefficients of Fe59 in Mo in the temperature range of 1000 to 1350°C. The diffusion coefficient at 1350°C was 1.2×10−12 cm2/sec, which was larger than the value for the impurity diffusion coefficient of Co in Mo obtained by Peart et al., but smaller than any value for the impurity diffusion coefficient of Fe in refractory metals as Nb, Ta and W at the corresponding temperature. It was found that the temperature dependence of Fe59 diffusivity in Mo showed the Arrhenius relationship, DFe→Mo=(0.15+0.09
−0.06)exp(−82.7±1.9⁄RT) cm2/sec, and no anomaly as in the impurity diffusion of Fe in β-Ti was observed. The activation energy for the diffusion of Fe in Mo was found to be smaller than that for the self-diffusion in Mo by about 10 kcal/mol. This trend holds in case of the impurity diffusion of Fe in the refractory metals such as Nb, Ta and W. The size effect appears to be important for the impurity diffusion of Fe in those metals, and the above trend may be tentatively explained by the small atomic radius of Fe with respect to those of such other elements. Using Swalin’s model, the activation energy for the impurity diffusion of Fe in Mo was calculated to be 84.4 kcal/mol, which was in good agreement with the experimental value. The empirical equation, lnD0=0.12Q−11.6, was obtained by the data on the self-diffusion of Mo, Nb, Ta and W the impurity diffusion of Fe and the other elements in these metals.View full abstractDownload PDF (496K) -
Masakazu Nakao, Takayuki Nakamura1973 Volume 37 Issue 7 Pages 737-745
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of ordering on the changes of electrical resistivity in Fe-Si alloys containing 6∼12 at% Si was studied. The alloys were annealed isochronally or isothermally after quenching from the disordered state, and then the change in electrical resistivity was measured in liquid nitrogen.
In the isochronal annealing at 20°C/20 min, the electrical resistivities of 6.4, 8.7 and 10.4 at% Si alloys increased between 330°C and 500°C in comparision with those of the quenched state. On the other hand, the resistivity of 12.2 at% Si alloy decreased between 330°C and 650°C. In the isothermal annealing at 360°C, the resistivities of 6.4, 8.7 and 10.4 at% Si alloys increased gradually with annealing time, but that of 12.2 at% Si alloy decreased as was expected from the results obtained by the isochronal annealing. The changes were reversible and the amounts of the changes showed good correspondence with Si contents.
The increase of electrical resistivity observed in 6.4, 8.7 and 10.4 at% Si alloys was the same phenomena as the so-called “K-state” observed in Fe-Al alloys. From the electron microscopic observation and X-ray diffraction analysis, it may be concluded that the increase of electrical resistivity was due to the formation of short range order. In the case of 12.2 at% Si alloy, on the other hand, the short range order already existed in the quenched state and the decrease of resistivity on further annealing was attributed to the increase of the long range order of the DO3 type. Analyzing the observed curves of electrical resistivity, the activation energy for the B 2→DO3 ordering of 10.4 and 12.2 at% Si alloys was determined as 28 and 39 kcal/mol and the order of reaction was 1.4∼2.0 and 1.4∼1.6 respectively.View full abstractDownload PDF (1184K) -
Namio Ohtani, Shigeru Asano, Yoshio Fujishima, Yoshikazu Yamamasu1973 Volume 37 Issue 7 Pages 746-753
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe relation between hydrogen-induced transformed phases and embrittlement was examined in 18-8 stainless steel. The results obtained are as follows:
(1) The maximum of embrittlement is observed at −15°C in 18-8 stainless steel (fcc) when the steel is charged with hydrogen at cathodic current density ic=0.2 A/cm2 for 1 hr. This behavior of embrittlement is similar to that in bcc metals.
(2) At the early stage of hydrogen absorption transformed phases, “εH” and “γH”, are found which seem to be hydrogen-absorped unstable phases of ε and γ respectively. These phases changes by the discharge of hydrogen as follows:
(This article is not displayable. Please see full text pdf.)
(3) As for the relation between cracking and phase transformation, it is shown that cracks occur just after the transformation of εH and γH to ε, α′ and γ.
(4) Apparent activation energies Q obtained from the recovery of ductility and the transition from εH to ε+α′ are estimated 10.5 and 13.3 kcal/mol respectively. These values are nearly equal to the value of the activation energy which has been measured for the diffusion of the hydrogen through austenitic stainless steel. Then the structural change of εH phase accompanied with the discharge of hydrogen and hydrogen embrittlement seem to be connected with the diffusion of hydrogen through 18-8 stainless steel.View full abstractDownload PDF (761K) -
Keijiro Nakasa, Hideo Takei, Yasuhiro Ishio, Shunsuke Wakaoka1973 Volume 37 Issue 7 Pages 754-763
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESS500°F embrittlement in various steels (JIS: S 15 C, S 35 C, SNCM 8, SKS 3 and SKD 5) were studied in terms of fracture toughness.
The results obtained are as follows:
(1) 500°F embrittlement reveals itself clearly in crack initiation resistance K*C or crack propagation resistance KC, but not in plane strain crack propagation resistance KIC. This indicates that the plastic deformation under plane stress at notch or crack tip is necessary for occurrence of 500°F embrittlement.
(2) In order to detect 500°F embrittlement of these steels sensitively, a smaller ratio of the notch root radius to the specimen thickness must be chosen as plane strain fracture toughness KIC in the as-quenched state is larger, and vice versa.
(3) The dimple fracture occurs not only in the toughened specimen but also in the embrittled one, so that 500°F embrittlement is not necessarily connected with intergranular fracture.View full abstractDownload PDF (1457K) -
Yoshinori Fujimura, Katsutoshi Kondo, Takeshi Onda1973 Volume 37 Issue 7 Pages 764-770
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo obtain a better understanding of high temperature creep deformation, high temperature short time creep tests have been done in vacuum (∼10−5 mmHg) on high purity nickel, OFHC copper and 20% Cr-30% Ni low carbon austenitic steel. By continuously observing surface structures revealed by thermal etching during a test with an optical microscope, investigation was made on how the microstructural change during deformation could be made clear from the results and the following conclusions were obtained. (1) In the cases of nickel crept at 850, 900 and 950°C under stresses of 1.0∼2.0 kg/mm2, OFHC copper at 800, 850 and 900°C under stresses of 0.3∼0.9 kg/mm2 and austenitic steel at the same temperatures as in OFHC copper under stresses of 1.0∼3.5 kg/mm2, subboundaries start to form at the very early stage of transient creep. They gradually develop inside grains and then form subgrains at the end of transient creep. Subgrains thus formed do not change their shape during steady state creep. (2) Characters of subgrains formed in every specimen are greatly affected by stress rather than temperature. That is, the higher is the stress the finer is the structure, and there also is a tendency to change its shape from polygonal to rectangular. (3) In pure nickel when temperature is high and stress is low, recrystallization is easy to occur in some areas inside a grain during creep. On the other hand, in OFHC copper and austenitic steel, coarse facetings are formed in a considerable number of grains; in some grains they cover the area. (4) Grain boundaries and subboundaries can be observed because of grooving along them. But in the area where coarse faceting are observed, subboundaries are quite difficult to be observed. (5) By comparing etch pit structures, deformation structures in the surface layer and inside a specimen are concluded to be the same.View full abstractDownload PDF (2104K) -
Toranosuke Kawaguchi, Koichi Ogawa1973 Volume 37 Issue 7 Pages 771-777
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMagnetic properties of Fe-Cu-Mn ternary alloys of 45 Fe-Cu-Mn and 80 Fe-Cu-Mn were investigated. Additions of less than 3 wt% manganese did not change the dendritic structures of Fe-Cu alloys, retaining their good workability. The addition of manganese to Fe-Cu binary alloys improved the coercivity, squareness and residual induction even with a low degree of cold reduction. The heat-treatment at 350∼500°C after the cold-reduction was necessary to obtain such high values of magnetic properties as Br 15.5 kG, Hc 55 Oe and Br⁄B100≥0.96 for 80 Fe-1.7 Mn-Cu alloy, and Br 7.5 kG, Hc 350 Oe for 45 Fe-1.8 Mn-Cu alloy.
Magnetic torque measurments indicated that the improvement of squareness by heat-treatment was due to a strong uniaxial magnetic anisotropy which was induced by the application of cold-reduction and subsequent heat treatment. The values of coercivity and residual induction (Br) were changed by a combined effect of heating time (t) and heating temperature (T), obeying the following equations: Hc∝−logt and Hc∝exp(±E⁄RT), respectively. These equations are very convenient to control the magnetic properties of Fe-Cu-Mn ternary alloys.View full abstractDownload PDF (1181K) -
Atsumi Ohno, Tetsuichi Motegi1973 Volume 37 Issue 7 Pages 777-780
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo find the effect of small additives on the undercooling of pure Sn, and about 15 grams of Sn-0.1% Cd, Sn-0.1% Ag, Sn-0.1% Zn, Sn-0.1% Pb, Sn-0.1% Sb, Sn-0.1% Bi and Sn-0.1% Al were held in pyrex glass containers after removing the oxide film from their molten surface by means of filtration.
The degree of undercooling of each alloy was repeatedly measured first with increasing degree of overheating up to 800°C above their melting points, and then with decreasing degree of overheating.
Three types of additives were found; (1) Al, Sb and Zn apparently decreased the degree of undercooling of pure Sn. (2) Ag and Pb did not show any effect on the degree of undercooling of pure Sn. Bi first showed a tendency similar to that of Ag and Pb but it increased the degree of undercooling of pure Sn when the evaporation of Bi occurred at 800°C above the melting point. (3) Cd increased the degree of undercooling of Sn.View full abstractDownload PDF (353K) -
Junichi Kaneko1973 Volume 37 Issue 7 Pages 780-787
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSUnidirectional solidification was carried out for Al-Mg2Si monovariant eutectic alloys of three different compositions. These are an alloy of Al-Mg2Si quasi-binary eutectic composition (Alloy E), an alloy containing excess Mg (Alloy M) and an alloy containing excess Si (Alloy S). The relations have been studied between the conditions of unidirectional solidification and the metallographic structures of the specimens. The obtained results are summarized as follows:
(1) The duplex structure was obtained when the specimen was grown at below 3.5 cm/hr for Alloy E and below 13 cm/hr for Alloy M, in which the Mg2Si rods and plates were alighned in the direction of growth. For Alloy S, no duplex structure was obtained by unidirectional solidification. The discussions based on the Al-Mg-Si ternary phase diagram were given to show that the plane front growth in the Al-Mg2Si monovariant eutectic reaction is more stable with respect to excess Mg than excess Si.
(2) For the specimens showing the duplex structure, the average distance between the neighboring Mg2Si rods or plates, λ, was shown to be related to the growth rate, R, as λ2R=2.0×10−10 cm3/sec. It is considered that the mechanisms of growth in such monovariant eutectic reaction is similar to those in nonvariant eutectic reaction. By using the equation derived by Jackson and Hunt, the value of interfacial energy between Al and Mg2Si was rounghly estimated to be 280 erg/cm2.
(3) In the Al-Mg2Si duplex structure, a unique crystallographic relationship between Al and Mg2Si was found and may be described as: growth direction\varparallel⟨100⟩Mg2Si\varparallel⟨100⟩Al, and interface \varparallel{011} Mg2Si\varparallel{001} Al.
Another relation: interface \varparallel{001} Mg2Si\varparallel{011} Al is also considered to be coexisting.View full abstractDownload PDF (1559K) -
Yoshiaki Kuniyasu, Toshinari Matsutani, Katsunori Ueda1973 Volume 37 Issue 7 Pages 787-793
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSZinc die casting alloys such as Zamak-3 tend to reduce impact strength and dimensional stability on aging. A large number of investigation have been carried out about the changes of their physical and mechanical properties on aging. British Standard 1003-4 specifies dimensional stabilizing treatments for these alloys to prevent dimensional changes on aging after die casting. This treatment consists of heating in air at a temperature of 100±5°C for six hr from time when castings attain this temperature.
In this paper the authors report the result of research on the aging characteristics of Zamak-3 by using a measurement of adiabatic specific-heat and also clarify the thermal change of this alloy during the stabilizing treatment.
The results obtained from this investigation are as follows:
(1) Regardless of the history of the sample, the zinc die casting alloy showed an endothermic reaction at 275°C corresponding to the temperature of the monotectic transformation of the alloy.
(2) The zinc die castings removed from the dies at the temperature of 225°C and quenched into water of 19°C (sample B) showed an exothermic reaction of 142 cal/mol at the temperature range of 40 to 180°C.
(3) The zinc die castings cooled freely in air at room temperature after die casting (sample A) showed an exothermic reaction of 43 to 56 cal/mol at the same temperature range as above.
(4) Regardless of the history of the sample any exothermic reaction could not be found in the sample treated by the stabilizing treatment.
(5) The sample heat-treated at a temperature of 350°C for 24 hr and then water-quenched generated heat by 186 cal/mol at the same temperature range as above.
(6) The activation energy on aging of Zamak-3 alloy was 12.6 to 14.6 kcal/mol.
(7) The entropy change of Zamak-3 alloy was 0.10 to 0.15 cal/mol·deg at 100°C.
(8) The entropy change of Zamak-3 on the monotectic transformation was about 0.17 cal/mol·deg at 275°C.
(9) The sample water-quenched right after die casting had more internal energy by about 110 cal/mol and also had more entropy by 0.28 cal/mol·deg at the thermodynamic standard state (25°C. 1 atm) than the sample cooled freely in air at room temperature after die casting. The free energy of the former was higher than that of the latter by 26 cal/mol.View full abstractDownload PDF (659K) -
Kazuyoshi Takezawa, Shin’ichi Sato1973 Volume 37 Issue 7 Pages 793-799
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSVery fine contrasts have often been observed in transmission electron microscopic images of quenched β-brass crystal. The contrasts are related to the presence of very fine transformation products in metastable matrix crystal. The crystal structure of the product has been invertigated in this survey by analysing electron diffraction patterns containing additional diffraction spots produced by the products. The mechanism of the transformation was also discussed.
The crystal structure obtained is an orthorhombic structure with A=(2a⁄3)[1\bar12]β1, B=(a⁄2)[1\bar1\bar1]β1, C=a[110]β1, which is also considered as a deformed hcp structure. It is supposed that the (110)[\bar110]β1 shears play an important role in producing the fine product, that is, the transformation possesses a martensitic nature. The fine products are thought as embryos of close-packed structure, such as martensite or bainite, not having enough energy to grow in large and perfect close-packed crystals.View full abstractDownload PDF (1118K) -
Hideaki Kawabe, Masaharu Takamura, Akira Ohtsuka, Nobuyuki Shinohara1973 Volume 37 Issue 7 Pages 800-801
Published: 1973
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (338K)
- |<
- <
- 1
- >
- >|