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Volume 20, Issue 2
Displaying 1-7 of 7 articles from this issue
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Noriyuki Kuwano, Toshihiro Doi, Tetsuo Eguchi1979 Volume 20 Issue 2 Pages 37-43
Published: 1979
Released on J-STAGE: June 01, 2007
JOURNAL FREE ACCESSThe martensites of Cu-22.1∼24.7 at% Al, either undeformed or deformed by filing, were annealed below the peritectoid temperature of the α2 phase, and the change in their structures on annealing was investigated by means of X-ray diffraction. The annealing behavior was found as follows: (1) the undeformed martensite transforms very slowly into the α2 phase, (2) the deformed martensite with Al less than 24 at% decomposes quickly into a mixed phase of (α+γ2), before reaching its equilibrium state of the α2 phase, and (3) the deformed martensite with about 25 at% Al recovers first to the undeformed martensitic structure and then transforms into the α2 phase. It is concluded that the annealing behavior of the deformed martensites in the early stage is governed by two competitive reactions, namely, the recovery to the undeformed martensitic structure and the decomposition into the mixed phase of (α+γ2).View full abstractDownload PDF (14477K) -
Toyokazu Matsuyama, Hajime Suto1979 Volume 20 Issue 2 Pages 44-50
Published: 1979
Released on J-STAGE: May 22, 2007
JOURNAL FREE ACCESSThis paper describes the work on the application of “AES” to the quantitative analysis of grain boundary fracture surfaces of Fe containing 0.05 to 1.7 wt% P quenched from the temperature in the range of 500 to 1150°C. In low P alloys the segregation levels of P at grain boundaries increased proportionally with the bulk concentration and inversely with the quenching temperature. The enrichment ratio was on the order of 10. In high P alloys the saturation level of segregation was about 15 at% P. On the basis of these experiments, the boundary structure at the saturation level was discussed.View full abstractDownload PDF (13816K) -
K. Akechi, Z. Hara1979 Volume 20 Issue 2 Pages 51-56
Published: 1979
Released on J-STAGE: May 22, 2007
JOURNAL FREE ACCESSBoron fibre reinforced aluminium composite was prepared by a resistance sintering process. A mixture of atomized aluminium powder (−150 mesh) and boron fibre (200 μmφ, tensile strength 3200 MPa) was resistance sintered for 1.2∼1.5s. When a composite was made with an appropriate power input so as not to melt aluminium matrix excessively, a sound fibre-matrix interface without a heavy reaction layer was formed and the mechanical properties of the obtained composite was excellent (for example, Al-20 vol%B: 500 MPa).View full abstractDownload PDF (11561K) -
Masaaki Hamano, Seishi Yajima1979 Volume 20 Issue 2 Pages 57-60
Published: 1979
Released on J-STAGE: May 22, 2007
JOURNAL FREE ACCESSMagnetic properties of hexagonal Y2+xCo17−2x single crystals with 0.23≥x≥−0.073, in which paired Co atoms are disorderly substituted by Y atoms in proportion to x, have been studied over a temperature range from 77 to 575 K . Saturation magnetization and Curie temperature decrease monotonically with increasing x. The magnetocrystalline anisotropy constant K1 calculated from magnetization data changes its sign from negative to positive at small x at all the temperatures studied, for example, at x=0.115 at 77 K . The local anisotropy constant of the paired Co atom is estimated from the variation of K1 with x and found to be −1720 m−1/Co at 77 K . Anisotropic behavior of Co in each crystallographic site in 2–17 type alloys is discussed on the basis of the experimental data.View full abstractDownload PDF (7931K) -
Keikichi Nakamura1979 Volume 20 Issue 2 Pages 61-69
Published: 1979
Released on J-STAGE: June 01, 2007
JOURNAL FREE ACCESSThe deuteron magnetic resonance of tantalum deuterides exhibits spectra of unexpectedly large asymmetry parameter, which suggests the existence of atomic displacement of tantalum. The asymmetry parameter is maximum at a stoichiometric composition of Ta2D, and decreases as x in Ta2D1+x increases. This suggests that the difference in the deuterium population between the 2a and 2d interstices, which is the origin of the atomic displacement of tantalum, becomes smaller. The relation between the atomic displacement, Δ, and the asymmetry parameter, η, is calculated by using a simple electrostatic model and under the condition that the deuterium atoms jump rapidly between the 2a and 2d positions. Comparison of the calculated and the observed concentration dependence of η shows that the β type hydride in which one deuterium exists in the 2za and x deuterium in the 2d, is stable at least up to x=0.6.View full abstractDownload PDF (16565K) -
Keikichi Nakamura1979 Volume 20 Issue 2 Pages 70-75
Published: 1979
Released on J-STAGE: June 01, 2007
JOURNAL FREE ACCESSThe free energy of Ta2D1+x is represented as a function of a long-range order parameter z. z=1 corresponds to the β type deuteride based on the Ta2D superstructure; z=0 represents the δ type deuteride which is a non-stoichiometric form of the TaD superstructure. At the composition Ta2D1+x, z and temperature have the following relationship:
(Remark: Graphics omitted.)
Tc0 represents the β→δ phase transition temperature at x=0. Analysis of the above equation shows that Tc at x, Tcx, decreases according to Tc0(1−x2). At x=0.6, Tcx calculated from the observed Cp data by Asano et al. is very close to room temperature, which is consistent with the observed Cp data and β⁄δ phase boundary of the Ta–D phase diagram.View full abstractDownload PDF (347K) -
Akihisa Inoue, Takaharu Iwadachi, Tsuyoshi Masumoto1979 Volume 20 Issue 2 Pages 76-78
Published: 1979
Released on J-STAGE: May 22, 2007
JOURNAL FREE ACCESSDownload PDF (4944K)
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