Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 46 , Issue 9
Showing 1-15 articles out of 15 articles from the selected issue
  • Toshihito Kishi, Katsumi Suzuki, Takao Endo
    1982 Volume 46 Issue 9 Pages 841-847
    Published: 1982
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Hot compression tests of Ni were conducted in the range of temperature from 973 to 1223 K at strain rates from 3.3×10−4 to 8.6×10−3 s−1. Single and multi peak behaviours associated with dynamic recrystallization were observed in flow stress-strain curves under the present experimental conditions. The dynamic restoration rate (r=−∂σ⁄∂t) and the work hardening rate (h=∂σ⁄∂ε) were measured as a function of strain by means of stress relaxation analysis. Values of r and h sharply increased at a strain of about 0.7εpp is the strain to the flow stress peak). They reached maximum values at εp and sharply decreased before the softening of flow stress came to an end. r and h values remained constant during steady states. These behaviours of r and h were plausibly interpreted as follows: (1) The production rate of dynamically recrystallized grains is maximum around a peak strain. (2) Newly formed fine grains are liable to be deformed preferentially since they are much softer than old grains around them.
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  • Yasumasa Koyama, Toshiyasu Ukena, Osamu Nittono
    1982 Volume 46 Issue 9 Pages 848-855
    Published: 1982
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Phase changes during aging of indium-(12-14 at%) lead alloys have been studied by means of X-ray diffractometry and metallographic techniques. These indium alloys, when cooled from a high-temperature phase and then aged at room temperature, show four kinds of phase change depending on the concentration of lead as follows: (a) fct(ca>1)→fct(ca>1)+fct(ca<1), (b) fcofco+fct(ca<1)→fct(ca>1)+fct(ca<1), (c) fct(ca<1)→fco+fct(ca<1)→fct(ca>1)+fct(ca<1) and (d) fct(ca<1)→fct(ca>1)+fct(ca<1). The fco phase is a metastable one and is not expected from a conventional equilibrium phase diagram of the In-Pb alloy system. In a composition range where the fco phase appears, the coexistence of fco and fct(ca<1) phases is always found. These phase changes are well explained in terms of thermodynamics, by assuming a free energy-composition curve for each existing phase. When the fco phase precipitates in the fct phase, i.e. in the case of (c), a banded surface relief structure due to {110}fct,ca<1 twins appears. This precipitation is a kind of the Bainite reaction and takes place by a mechanism involving macroscopic cooperative movements of atoms, being quite similar to a martensitic transformation in indium-rich alloys. The features of structural changes during aging are also discussed on the basis of the Landau theory concerning structural phase transformations.
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  • Hidehiko Matsuda, Yasushi Umemoto, Koji Tanoue
    1982 Volume 46 Issue 9 Pages 856-862
    Published: 1982
    Released: April 04, 2008
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    Measurements of the electrical resistivity, simple tensile tests and stress relaxation tests are made to investigate the hardening mechanism at the early stage of ageing in Al-Zn alloys. There exists a good linear relationship between the flow stress σ and the square root of the plastic strain ε1⁄2 at any stage of ageing for pure Al and Al-Zn alloys deformed at \dotε=10−4 s−1 and 77 K. The strain independent flow stress σ0 obtained by extrapolating ε1⁄2 to zero increases drastically in the concentrated alloys as ageing proceeds. This initial agehardening can be explained by the interaction between dislocations and the coherent strain fields as proposed by Gerold et al.
    The specific activation volume ΔV concerning the thermally activated shearing of GP zones by dislocations is obtained from stress relaxation tests, assuming that the rate controlling process is a consecutive one of the dislocation intersection and the shearing of GP zones by dislocations for Al-Zn alloys. As ageing proceeds, ΔV increases until the electrical resistivity reaches its maximum. Marked changes in ΔV may results from a considerable increase in the number of small GP zones at the initial early stage of ageing.
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  • Kusuhiro Mukai, K\={o}ji Funatsu, Kyoko Wasai, Toshio Kitajima
    1982 Volume 46 Issue 9 Pages 863-869
    Published: 1982
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Using an alumina capsule, an isobaric method has been developed to measure the manganese activity in the liquid Co-Mn alloys by the aid of the Fe-Mn alloys as a reference system. Results obtained are as follows: (1) Activities of manganese show negative deviations from Raoult’s law and small variations with temperature within the range of experimental error. (2) Activity coefficients of manganese and cobalt are expressed by the following equations.
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    \ oindent(3) The liquid Co-Mn system is classified approximately as a regular solution, according to the following facts: (i) Absolute values of heat of mixing are much smaller than RT, (ii) Δ\barSMnXS except for NMn=0.1 and ΔSXS are nearly equal to zero, (iii) linear relations between logγMn and NCo2 hold for all over the range of manganese concentration, and the intersecting points at the ordinate are very close to the origin.
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  • Kusuhiro Mukai, Yoshimi Wasai, K\={o}ji Funatsu, Kyoko Wasai, Hideaki ...
    1982 Volume 46 Issue 9 Pages 870-877
    Published: 1982
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The manganese activity in the liquid Ni-Mn alloys has been measured by an isobaric method with an alumina capsule in which Fe-Mn alloys have been used as a reference system. Results obtained are as follows: (1) Activity of manganese shows remarkable negative deviations from Raoult’s law compared with the Co-Mn system in low manganese concentration range and has close values to those of the Co-Mn system in high manganese concentration range in the vicinity of NMn=0.9. In the concentration range, for NMn≤0.5 it increases with increasing temperature and vice versa in the range, NMn≥0.6. (2) Activity coefficients are expressed by the following equations:
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    \ oindent(3) Behaviours of thermodynamic properties, γMn, ΔH and Δ\barSMnXS, for the liquid Ni-Mn system indicate that the Ni-Mn system can be regarded neither as an ideal solution such as the liquid Fe-Mn system nor as a regular solution such as the liquid Co-Mn system. (4) Activities for the liquid Ni-Mn system are well described quantitatively by an ideal associated solution model, assuming the formation of species of associated compounds, NiMn and Ni3Mn, whose stoichiometric compositions are equal to those of the compounds in solid state. (5) Plots of lnγ°Mn in X (X=Mn, Fe, Co, Ni) against ZX show a convex curve with a maximum between ZFe and ZCo. A similar curve has been also found in the plots of the magnetic moment of the solid alloys against ZX.
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  • Munetaka Kuribayashi, Hisaki Okabayashi
    1982 Volume 46 Issue 9 Pages 877-886
    Published: 1982
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The influence of hydrogen on the mechanical properties of SUS 304 steel at low temperatures was investigated. The specimens which were heat-treated at 1073 K for 1.8 ks or solution annealed at 1373 K for 1.8 ks were cathodically charged with hydrogen at 323 K in a 0.5N H2SO4 solution. Results obtained are as follows:
    (1) The specimens which are heat-treated at 1073 K for 1.8 ks exhibit large hydrogen embrittlement by a low temperature testing at 77 K.
    (2) In the case of solution annealed specimens such a low temperature hydrogen embrittlement (LTHE) is not observed.
    (3) The specimens fractured in a manner of LTHE exhibit almost intercrystalline fracture.
    (4) The recovery of ductility due to the discharging of hydrogen at 1073 K or lower is also observed. However, the ductility is not completely recovered to the initial state of the specimens.
    (5) The apparent activation energy, Q, obtained from the recovery of ductility is 51 kJ/mol.
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  • Eiichi Takeuchi, Junichi Asami
    1982 Volume 46 Issue 9 Pages 886-891
    Published: 1982
    Released: April 04, 2008
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    Sliding wear characteristics of sintered Fe-Ni-Mo alloys impregnated with a thermoplastic synthetic resin, Nylon 11, were studied in order to examine the suitability as wear-resisting materials for machine parts. The wear test in unlubricated sliding was made on the three different series of these alloys containing various amounts of Nylon 11 as stator material in combination with a carbon steel S45C as rotor material. In the wear test at various sliding velocities ranging from 0.10 to 4.00 m·s−1 and at a contact pressure of 0.49 MPa, the material with a sintered density of 6.65 Mg·m−3, which was prepared by compacting the powder mixture at a pressure of 490 MPa, showed the best wear-resistance. The limiting conditions for effective lubrication with the impregnated Nylon 11 were determined from the relationships between wearing rate and sliding velocity and also between wearing volume and sliding distance. The critical sliding velocities for sudden changes in wear resistance at the contact pressures of 0.49, 0.98 and 1.96 MPa were 4.00, 2.00 and 1.50 m·s−1 respectively. The Nylon-impregnated materials showed a remarkable wear resistance, the specific wear rate of which was about one-four thousandths of that for the unimpregnated and one-tenth that for the SCM 435 steel treated by ion-nitriding.
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  • Keijiro Hiraga, Keisuke Ishikawa
    1982 Volume 46 Issue 9 Pages 892-900
    Published: 1982
    Released: April 04, 2008
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    Low temperature tensile and Charpy V-notch impact tests were carried out for aged Fe-25Ni-15Cr-(1-5)Ti alloys. Microstructural examination was also made, and the relation between low temperature mechanical properties and aged microstructures of these alloys has been discussed. Results are as follows:
    (1) Aged microstructures of the alloys are classified into three groups: (a) γ+γ′-Ni3Ti, (2) γ+cellular η-Ni3Ti and (3) γ+γ′+η. Cellular reaction was remarkably accelerated with an increase in Ti or Ni content. Low temperature strength, ductility and toughness of the alloys depended upon the aged microstructures. Superior ductility and toughness were obtained in the case of (a).
    (2) Small amount of α′ martensite was introduced by tensile deformation in high-Ti alloys. In this study, however, the effect of strain-induced α′ martensitic transformation on low temperature strength and toughness of the alloys was found to be very small.
    (3) It was concluded that the optimum content of Ti in the alloys is in the range from 1.5 to 3 wt% for excellent mechanical properties at cryogenic temperature.
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  • Yutaka Kagawa, Yasuto Watanabe, Eiichi Nakata, Susumu Yoshida
    1982 Volume 46 Issue 9 Pages 900-907
    Published: 1982
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The fracture behaviors of copper matrix composites reinforced with helical tungsten fibers have been investigated experimentally. A length of tungsten fiber 150 μm in diameter was formed into a helix, whose helical angle was 78.4° and helical radius was 75 μm. Helical fibers were embedded in a copper matrix by mens of electrodeposition and vacuum hot-pressing techniques. Specimens were tensile-tested and their fracture behaviors were investigated. Observations of fracture surfaces and deformation of fibers in the matrix were also made. The results were compared with those on the straight fiber reinforced composites.
    It was found that the tensile fracture behavior of the helical fiber composite was not so catastrophic as the straight fiber composite. As to the two kinds of composites of the same volume fraction, fairly larger ultimate tensile strains were obtained with a small decrease in the ultimate tensile stresses by using the helical fibers instead of the straight ones as the reinforcing component. The portions of fibers pulled out were seen much longer for the helical fiber composites than for those with the straight fibers. Considerable debonding between the fiber and the matrix was observed near the fracture surface especially for the helical fiber reinforced composites.
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  • Kohei Kubota, Satoru Yamamoto
    1982 Volume 46 Issue 9 Pages 908-916
    Published: 1982
    Released: April 04, 2008
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    Dilatometric measurements were carried out during the first-stage graphitization of white cast irons. It has turned out that the data can not be analyzed consistently by the rate equations proposed by Johnson-Mehl or Austin-Ricketts. A new type of rate equation, y=1−exp{−(t⁄τ1)n1[1−e−(t⁄τ2)n2][1−e−(t⁄τ3)n3]−1} has been derived and proposed to interprete the data in terms of the following model: The rate of graphitization is controlled by the rate of interfacial reaction by which cementite dissolves in the austenite, and the number of dissolving cementite particles increases with the increase of volume of voids in which graphite nodules are formed.
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  • Satoru Yamamoto, Kohei Kubota
    1982 Volume 46 Issue 9 Pages 917-924
    Published: 1982
    Released: April 04, 2008
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    A kinetic study of precipitation process in Cu-Be alloys has been carried out mainly by electrical resistivity measurements. The main results are as follows: (1) It has turned out that the data can not be analyzed with the rate equations proposed by Johnson-Mehl or Austin-Ricketts. (2) A new type of equation, y=1−exp{−(t⁄τ1)n1[1−e−(t⁄τ2)]n2}, has been proposed, and the continuous precipitation inside grains and the discontinuous precipitation at grain boundaries are separated from each other. (3) The time-exponent and time-constant in the rate equation have been determined and explained in terms of a model in which the rate of precipitation is controlled by a diffusion process necessary for the growth of rod-like precipitates and the number of growing precipitates increases exponentially. (4) The effects of solution treatment temperature and additional elements have been discussed.
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  • Kiyoshi Watanabe
    1982 Volume 46 Issue 9 Pages 925-928
    Published: 1982
    Released: April 04, 2008
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    Iron and palladium alloys containing about 20-45 at% palladium showed a high coercive force and a large maximum energy product by a prolonged isothermal heat-treatment at a relatively low temperatures.
    The present work was carried out to investigate the relation between the heat-treatment and the phase transformations so as to obtain a better understanding of the phase components and the process of the transformation. For this purpose, the isothermal transformation (TTT) curves of the typical four kinds alloys were determined by means of X-ray diffraction.
    It becomes clear that the γ phase obtained by water-quenching changes to γ+α by heat-treatment at high temperature, and that by heat-treatment at low temperature, the γ phase changes to γ+α+γ1→α+γ1 or γ+α→α+γ1. According to the TTT curves, a relatively long tempering time is needed to form the γ1 phase which is essential for obtaining excellent permanent magnet properties. Furthermore, it has been found that there is an almost similar behavior in the transformation by the same tempering-treatment regardless of whether the alloys has been slowly cooled at a rate of 0.11-0.055 K/s or water-quenched from the homogenizing temperature.
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  • Hakaru Masumoto, Masakatsu Hinai, Showhachi Sawaya
    1982 Volume 46 Issue 9 Pages 929-934
    Published: 1982
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Effect of cold-working on the damping of furnace-cooled or water-quenched Al-Zn alloys with 0-100%Zn was studied by varying the reduction in area. Measurements of the logarithmic decrement δ and the regidity modulus G were carried out by the inverted pendulum method at a frequency of 1 Hz. The hardness Hv was measured using a micro-Vickers hardness tester, and the specific weight S by the Archimedean method.
    Except for the water-quenched alloys with 70-90%Zn, the heat-treated alloys have generally a low δ. The order of magnitude of δ in the alloys subjected to heat-treatments depends on the viscous flow at the grain boundary between α and β phases. Upon cold-working, the δ becomes considerably larger with increasing reduction in area. The increase in δ is due to the increasing boundary effect resulting from the refinement of grains and to the increasing viscous and hysteretic motions of dislocations.
    Hv values of the alloys with 10-70%Zn water-quenched from 673 K are considerably higher than those for furnace-cooling. On the other hand, the alloys with 80-90%Zn furnace-cooled show Hv values higher than those water-quenched. The nearer the eutectoid composition, the lower becomes the Hv value after cold-working. G values of the alloys water-quenched from 573 K or furnace-cooled from 573 and 673 K increase with increasing Zn content, while those after water-quenching from 673 K show a minimum value at 50%Zn. The G upon cold-working is nearly constant up to 40%Zn and increases rapidly with Zn content in excess of 40%, regardless of the prior heat-treatment. The S increases with Zn content, but the value is generally as small as 4.8 Mg/m3 even for the Al-70%Zn alloy.
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  • Hiroyasu Funakubo, Masatake Akaike
    1982 Volume 46 Issue 9 Pages 935-943
    Published: 1982
    Released: April 04, 2008
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    The mechanism of cold pressure bonding of low index surfaces of an Al single crystal at room temperature in ultra-high vacuum, was studied. This bonding was carried out by pressure load in ultra-high vacuum after removal of a surface film by means of Ar ion bombardment.
    Results obtained are as follows:
    (1) Fracture load and apparent fracture stress after cold pressure bonding, was greatest for the (001)-plane, and was smallest for the (\bar111)-plane. This fracture load increased linearly along with pressure load, and this stress was not influenced by pressure load.
    (2) The crystal rotation per unit length of the indentation created by pressing a spherical steel indenter, was greatest for the (001)-plane, and was smallest for the (\bar111)-plane. However, the area of the indentation surface was smallest for the (001)-plane, and was greatest for the (\bar111)-plane. The crystal rotation increased linearly along with the distance from the indentation center.
    (3) The fracture surface after cold pressure bonding, consisted of numerous little bonding islands in a stage of low pressure load. In a stage of higher pressure load, however, it consisted of large bonding islands and revealed a ductility fracture mode in Al (001)-plane. A fracture surface after cold pressure bonding of Al-ceramics, revealed markedly bonded traces at slip lines on its surface, mainly.
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  • Ken-ichi Miyazawa, Takao Choh, Michio Inouye
    1982 Volume 46 Issue 9 Pages 944-949
    Published: 1982
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The twin-roll rapid solidification process was investigated both experimentally and theoretically to explore rolling characteristics of the process.
    Results of the experiment using a Pb-Sb eutectic alloy show that the thickness of a rapidly solidified metallic ribbon decreases with increasing roll rotation speed and with decreasing initial roll gap and melt flow rate. The cross-sectional area of ribbon is in proportion to the ratio of the melt flow rate to the roll rotation speed and does not depend on the initial roll gap.
    Based on the reduction ratio in thickness of the solidified ribbon and the roll gap enlarged by a rolling load, effects of key process parameters on the ribbon geometry are discussed. The calculated roll separating force has been confirmed to agree well with the observed value.
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