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Volume 43, Issue 1
Displaying 1-11 of 11 articles from this issue
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Toshio Shimoo, Hiroshi Nagai, Hiroshi Kimura1979 Volume 43 Issue 1 Pages 1-7
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study was made on the dissolution rates of carbon in CaO-Al2O3 binary slag melted in a graphite or alumina crucible with carbon saturated iron.
In the case of pure carbon saturated iron, the dissolution of carbon in slag occurs mainly from graphite, while, in the case of silicon or aluminium addition to metal, it proceeds from the metal at the early stages of the reaction and then proceeds from the graphite.
The dissolution rate of carbon from graphite was expressed by a zeroth order reaction and its apparent activation energy was 587 kJ/mol for 50 wt.%CaO-50 wt.%Al2O3 slag. The rate increased in proportion to the 3/2th power of the activity of lime and to the ratio of slag-metal to slag-graphite interfacial area. Carbon dissolution from graphite was promoted by the addition of silicon and aluminium to metal, but it was reduced by the increase of PCO in the gaseous phase. This implies that the carbon dissolution proceeds electrochemically and its rate is controlled by a chemical reaction. On the other hand, the dissolution rate of carbon from metal is represented by a first order reaction and is controlled by the transport of carbon through the slag boundary layer.View full abstractDownload PDF (511K) -
Toshio Shimoo, Hiroshi Nagai, Hiroshi Kimura1979 Volume 43 Issue 1 Pages 8-13
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn this study, the reduction of alumina in CaO-Al2O3 binary slag by carbon saturated iron was investigated under various experimental conditions.
The reduction rate of alumina was represented by a zeroth order reaction and its activation energy was 619 kJ/mol for 50 wt.%CaO-50 wt.%Al2O3 slag. The rate of reduction increased linearly with the activity of AlO1.5 in slag and with the ratio of slag-graphite to slag-metal interfacial areas. The reduction rate of alumina was accelerated by the addition of silicon to metal. Furthermore, the reduction rate of alumina in CO atmosphere was about one-tenth that in Ar atmosphere.
It is supposed that the reduction rate of alumina is controlled by the cathodic reaction (Al3++3e=Al) involving the break-down of Al-O bonds in slag.View full abstractDownload PDF (368K) -
Hakaru Masumoto, Michio Kikuchi, Showhachi Sawaya1979 Volume 43 Issue 1 Pages 13-17
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSYoung’s modulus at high temperatures, thermal expansion, rigidity modulus, hardness and tensile strength at room temperature have been measured for Mn-Ni-Ti and Mn-Ni-Zr alloys subjected to various heat treatments and cold working. Young’s modulus vs temperature curves of the annealed ternary alloys indicate the changes associated with the phase transformation and with the antiferromagnetic\ ightleftarrowsparamagnetic transition. The temperature coefficient of Young’s modulus at room temperature are affected by annealing, cold working and reheating after cold working and composition. The temperature coefficient vs composition curves has a positive maximum, showing the Elinvar characteristics at room temperature. Young’s modulus, hardness and tensile strength of Mn-Ni binary alloys increase with increasing alloying element Ti or Zr.View full abstractDownload PDF (395K) -
Osamu Momose, Sosuke Uchida1979 Volume 43 Issue 1 Pages 18-22
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe properties of the gas nitrosulfurizing layer of steel and the wear of gas nitrosulfurizing steel were discussed.
A testing piece of S 25 C steel used as a stator was treated in an atmosphere of the carrier gas containing a NH3 and H2S mixture in the temperature range of 813 to 903 K for 180 min.
It was confirmed by X-ray diffraction that the surface products were FeS, Fe1−xS, Fe3N and Fe4N at each temperature.
The surface hardness and cross-sectional hardness of gas nitrosulfurizing steel decreased with increasing temperature.
The wear test was carried out without lubrication under the condition of 490 kPa and a combination with a rotor of S 45 C steel.
It was recoginized that the gas nitrosulfurizing of steel reduced adhesivity of the wear plane and improved the wear property of steel.View full abstractDownload PDF (438K) -
Yoshihiko Kunieda, Takeo Oki1979 Volume 43 Issue 1 Pages 22-29
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe suspension-electrolysis method was applied to driect leaching of metal sulfides. The anodic dissolution mechanism of β-ZnS in the suspension-electrolysis with a Pt anode was investigated in terms of the interfacial impedance and voltammgram on the anode. The results obtained are as follows:
(1) In a low electrode potential region in the anodic suspension-electrolysis of β-ZnS alone, the anodic reaction on the Pt anode is mainly the oxidation of H2S due to the H2S evolution-dissolution reaction of β-ZnS in acidic solution. The anodic reaction is controlled by charge-transfer and diffusion, simultaneously.
(2) In the anodic suspension-electrolysis, suspension-graphite particles are oxidized on the Pt anode electrochemically and have a higher potential. In the presence of β-ZnS, they restrain its dissolution with H2S evolution, and then it is dissolved by the S0 product-reaction by the galvanic reciprocal reactions with these oxidized graphite particles. The anodic reaction on the Pt anode in co-suspension of β-ZnS and graphite powder, is mainly the oxidation of the latter.
(3) In the presence of Fe3+, β-ZnS is dissolved by the reaction, ZnS+2Fe3+=Zn2++2Fe2++S0. The anodic reaction on the Pt anode is mainly the oxidation of product Fe2+ and is controlled by the charge-transfer reaction of Fe2+/Fe3+.
(4) Upon suspension-electrolysis of β-ZnS in co-suspending graphite powder and added Fe3+, the oxidation current is remarkably large. The anodic reaction on the Pt anode is also mainly controlled by the charge-transfer reaction of Fe2+/Fe3+.View full abstractDownload PDF (571K) -
Yutaka Nakayama, Yutaka Tatsumi, Kenji Morii, Mitsuo Mera1979 Volume 43 Issue 1 Pages 29-35
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSingle crystals of Cu-15 at%Al alloy having the(211)[\bar111]initial orientation were rolled at room temperature. A detailed metallographic examination of deformation structure and a measurement of the orientational change were carried out from the viewpoint of shear bands.
In the present alloy, nearly the same type of shear bands as that in α-brass was formed after the onset of extensive mechanical twinning. It was found that the shear bands occurred in a sequence of the following processes: (1) Nucleation of a region with lattice rotation within the substructure of twin lamellae, (2) generation of peculiar slip traces in that region, (3) formation of a micro shear-band as a result of the accumulation and/or linear arrangement of the peculiar slip traces, and (4) growth of the micro shear-band. The changes in orientation during rolling were closely correlated with the activation and development of the shear bands.View full abstractDownload PDF (1166K) -
Hiroshi Mabuchi, Yutaka Nakayama1979 Volume 43 Issue 1 Pages 36-42
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe latent hardening in Cu-6.5 at%Si and Cu-15 at%Al single crystals has been investigated by measuring the flow stress on secondary systems. Secondary crystals oriented for coplanar and intersecting slips were cut from prestrained parent crystals and tested in tension. The results obtained are as follows.
(1) There is a clear distinction between the latent hardening of coplanar and intersecting slip systems. The flow stress and the work hardening rate on coplanar slip systems are similar to those on the primary slip. While, on intersecting slip systems the flow stress increases and the work hardening rate decreases compared with those on the primary slip.
(2) In latent hardening ratio (LHR) there is a significant difference among the intersecting systems. Particularly, the LHR on the cross glide systems are considerably lower than on the other intersecting systems. These results are discussed in terms of the strength of the interaction between the glide dislocations on intersecting systems and the forest of primary dislocations.
(3) The critical resolved shear stress has been related to the forest dislocation density (ρf≥∼4×105 cm−2) in the following equation: τy=τ0+αμb(ρf)1⁄2, where τ0=15.2 MPa and α\simeq1.0 in Cu-15 at%Al crystals deformed at room temperature.
(4) The LHR is determined by the difference between the forest dislocation density on the primary slip system and on the secondary slip system. Also, in the case of a large value of τ0, the contribution of τ0 to LHR cannot be neglected.View full abstractDownload PDF (704K) -
Harusige Tsubakino, Ryoichi Nozato1979 Volume 43 Issue 1 Pages 42-48
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSOn the cell growth of discontinuous precipitation has been investigated by means of metallographic observations in Cu-6.2, 9.3 and 13.4 at%Be alloys. The growth rate (G), interlamellar spacing (l) and volume fraction of the γ phase (fγ) in the discontinuous precipitation cells have been determined by quontitative metallographic measurements in the specimens aged at temperatures from 473 to 823 K.
The results obtained are as follows: (1) l increases with ageing temperature, whereas G first increases, passes through a maximum and then decreases. (2) At constant ageing temperature, G and 1/l increase with increasing Be content but Gl2 remains almost consatnt. (3) The fraction of equilibrium segregation is 0.79∼0.87 except for the ageing temperature in the vicinity of the solvus temperature. (4) Grain boundary diffusivities, obtained from the modified Turnbull theory proposed by Aaronson et al., are reasonable over a wider ageing temperature range than that obtained from the Turnbull and the Cahn theory. Therefore, it can be concluded that during the growth of cells, mass transport of Be occurs by grain boundary diffusion. (5) At constant temperature, G is proportional to the square of the dissipated free energy change. (6) The interfacial energy of the broad faces of the cell lamellae, obtained from the Cahn theory, is 3-15 times larger than the value for the grain boundary energy in Cu alloy.View full abstractDownload PDF (635K) -
Toshiaki Yoneoka, Michio Yamawaki, Masayoshi Kanno1979 Volume 43 Issue 1 Pages 49-55
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHigh energy ion backscattering method is suitable to make nondestructive analysis of depth distribution of elements within one micrometer from a surface. However, this method has disadvantage of poor mass discrimination. In order to overcome this disadvantage, 16O ion particles accelerated up to an energy of 15 MeV were used instead of 4He ions. This improved backscattering method was applied to an analysis of the initial stage of the high temperature oxidation of Ni-Nb alloys.
The 95Ni-5Nb alloy and 90Ni-10Nb alloy were prepared in a plasma-jet furnace, and the cold-rolled specimen coupons were oxidized under oxygen pressure of 6×10−2 Pa at 1023 K. Each specimen was oxidized until electrical microbalance reading showed that its surface oxide film could have a thickness of about one micrometer. The oxidized specimens were examined by using the backscattering method together with conventional X-ray diffraction, high energy electron diffraction and scanning electron microscopy. The 95Ni-5Nb specimen was covered mainly with a flat dense oxide layer of M-Nb2O5 and partially with granular particles of T-Nb2O5. On the other hand, the 90Ni-10Nb specimen was covered mainly with granular oxide particles. It was clarified with the backscattering method that the thickness of the oxide film formed on the 95Ni-5Nb alloy ranged from 20 to 120 nm. Whilst, the thickness of the oxide film on the 90Ni-10Nb alloy ranged from 40 to 200 nm. The weight gain due to oxidation was mainly attributed to the formation of an internal oxidation zone 6∼8 μm thick. The oxide particles in the outer part of the internal oxidation zone were tentatively identified to be T-Nb2O5, and those in the inner part was to be a lower niobium oxide.
The backscattering analysis using 16O ions has been demonstrated to be highly useful in the studies of material surface phenomena, including high temperature alloy oxidation, on account of its improved mass discrimination compared to the 4He backscattering.View full abstractDownload PDF (746K) -
Masayasu Kawahara, Kenji Morinaga, Tsutomu Yanagase1979 Volume 43 Issue 1 Pages 55-60
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe measurements of the viscosity and the electrical conductivity for Na2O-SiO2-NiO and CaO-SiO2-NiO melts have been conducted to find out the behavior of NiO in these systems.
When NiO was added to the melt having the composition of Na2O/SiO2=1/4∼3/2, the viscosity decreased with increasing NiO content, while the electrical conductivity was approximately constant or slightly increased up to about 15 mol% of NiO.
When NiO was added to the melt having the composition of CaO/SiO2=2/3∼1, the viscosity decreaed and the electrical conductivity increased remarkably up to about 10 mol% of NiO. They tended to remain almost constant, however, when the NiO content increased up to 20∼25 mol%. In the CaO-SiO2-NiO system, the viscosity decreased and the electrical conductivity increased when 5∼15 mol% of CaO was replaced by NiO.
The strength of NiO as a basic oxide was higher in the CaO-SiO2-NiO system than in the Na2O-SiO2-NiO system and also than that of CaO up to about 10 mol% of NiO, but its strength as a basic oxide decreased with increasing NiO content in the melt.View full abstractDownload PDF (464K) -
Nobuyuki Mori, Keisaku \={O}gi, Kimio Matsuda1979 Volume 43 Issue 1 Pages 61-69
Published: 1979
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMacrosegregation in ingots mainly result from interdendritic fluid flow which arises because of the difference in the density of the interdendritic liquid from that of the bulk liquid. In this paper, Al-5.5%, 15%, 25%Cu, Al-14%Mg, and Al-6%Mg-1.2%Cu alloys were holizontally, unidirectionally solidified to clarify the effect of the solute elements and the freezing condition on macrosegregation.
Almost no macrosegregation occurred in Al-6%Mg-1.2%Cu alloy, in which the density of interdendritic liquid (ρLs) is nearly equal to that of bulk liquid (ρP0) during the solidification, while normal and gravity segregation and string ghosts appeared at low solidification rates (R) in Al-Cu and Al-Mg alloys in which ρLs differs from ρL0.
The effective segregation coefficient (Ke), the ratio of the solute concentration in the solid to that in the bulk liquid decreased almost linearly with the increase in the reciprocal of R. The effect of R was larger in Al-Cu alloys than in Al-Mg alloys.
Normal and gravity segregation was found to result mainly from the flow of solute rich interdendritic liquid into the bulk liquid, through the string ghosts in the liquid-solid region.View full abstractDownload PDF (920K)
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