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Volume 32, Issue 8
Displaying 1-6 of 6 articles from this issue
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Mitsuharu Shimizu, Hiromasa Takeuchi1985 Volume 32 Issue 8 Pages 289-293
Published: November 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSBy blowing nitrogen gas into the molten state of Al-5 to 50%Pb alloys, which was discharged from the molten metal nozzle at the bottom part of graphite crucible, powder was produced. The solidification structure and cooling rate of the powder were examined. The results obtained are summarized as follows: The particle shape was not spherical but tear-drop-like, and the particle size was from 10 to 500 μm. It was found that lead particles were dispersed in the aluminum matrix in all the cases. The cooling rate of this powder was from 50 to 5800 k/s. The value of the heat transfer coefficient at the powder-gas interface was from 89 to 577 J/m2.s.k.View full abstractDownload PDF (4816K) -
Kazuhiko Majima, Masahiro Kihara, Keiichiro Shoji1985 Volume 32 Issue 8 Pages 294-300
Published: November 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe sintering characteristics of Ti-Co binary mixed powder compacts containing up to 10 wt%Co were studied by the dilatometric method, and the diffusional process between Ti and Co during sintering was investigated by EPMA.
The results obtained are summarized as follows:
(1) The addition of Co was quite effective to the densification of titanium powder compacts. For example, the density of Ti-Co binary mixed powder compacts containing only 2 wt%Co sintered at 1573 K for 3.6 ks reached more than 99% of the theoretical value.
(2) The contracting phenomenon observed in the high temperature range above 1073 K during sintering of Ti-Co binary mixed powder compacts was confirmed to be related to the network formation of the Co-rich phase along the surfaces of Ti powders.
(3) The above mentioned Co-rich phase formed along the surfaces of Ti powders was clarified to be the very fine eutectoid structure composed of α-Ti and Ti2Co.View full abstractDownload PDF (6894K) -
Hisashi Suzuki, Hideaki Matsubara, Masaya Asano1985 Volume 32 Issue 8 Pages 301-304
Published: November 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSTiC0.5N0.5-(2-18)vol%Mo2C-16.4vol%Ni alloys were sintered and HIP-treated at 1723 K, and then resintered at 1823 K. The microstructure, transverse-rupture strength at room temperature and 1273 K, etc. of the alloys were studied in relation to Mo2C content. The TRS at room temperature of the resintered alloy increased with increasing Mo2C content and attained a maximum with the Mo2C content of about 10%. The TRS and resistance to deformation at 1273 K became higher with increasing Mo2C content. The discussions on these results were given.View full abstractDownload PDF (3820K) -
Hisashi Suzuki, Hideaki Matsubara, Takeshi Saitoh1985 Volume 32 Issue 8 Pages 305-310
Published: November 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe room temperature transverse-rupture strength (TRS) of nitrogen contained cermets was studied in relation to the nitrogen content and particle size. The TiC-, TiC0.7N0.3- and TiC0.5N0.5-10.0 vol%MO2C-16.4 vol%Ni alloys HIP-treated and then resintered were used as the specimens. The resintering process employed here was to eliminate the nickel pools often developed in nitrogen contained alloys, when HIP-treated.
The TRS of the nitrogen contained alloys had a tendency to increase with decreasing particle size of carbonitrides, because the defect size decreased with the particle size. The intrinsic strength of the nitrogen contained alloys showed a maximum of about 6.0 GPa at the particle size of 1.0 μm. The TRS as high as 3.2 GPa or more was observed when the particle size became 0.5-0.8μm. It was suggested that the strength of nitrogen contained alloys could be increased further with decreasing defect size.View full abstractDownload PDF (3255K) -
(4th Report) A preferable alloying element for carbide formationKanji Notomi, Seiya Furuta, Nobuyasu Kawai1985 Volume 32 Issue 8 Pages 311-317
Published: November 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA study has been made to reveal a preferable alloying element for the formation of massive carbides in HIP processed roll steel, pre-mixed with high alloy iron powder, and the mechanism of the formation has been discussed. Five kinds of high alloy gas atomized iron powders (3.5%C+14%Cr, 3%C+30%Mn. 4%C+8%V, 3%C+10%Mo and 3%C+10%W) were mixed with gas atomized adamite steel powder containing 1.7%C-1.2%Cr, respectively, followed by HIP processing to full density. The micro-hardness measurement, the observation of microstructure and EPMA analysis were carried out to examine the extent of carbide formation.
The results showed that high chromium iron powder and high manganese iron powder changed into massive carbides (M3C, M7C3), whose size is almost the same as that of powder particles during HIP processing, whereas high vanadium iron powder, high molybdenum iron powder and high tungsten iron powder do not change into massive carbides, because these elements make those carbides unstable.View full abstractDownload PDF (4310K) -
Oxidation of Sintered IN-100Hiroshi Nagai, Masao Morishita, Yuuji Miki, Keiichiro Shoji1985 Volume 32 Issue 8 Pages 318-322
Published: November 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe isothermal oxidation behavior of sintered IN-100 superalloy containing 1 mass% dispersoids of Y2O3 and La2O3 in air at 1273 K was investigated. Atomized IN-100 alloy powders were mixed with Y2O3 or La2O3 powders in a disc-mill under an argon atmosphere and hot-pressed. The particle shape and microstructure of the disc-milled powders resembled very closely to those of mechanically alloyed powder.
Y2O3 dispersion reduced the oxidation rate of sintered IN-100 alloy more markedly than La2O3 dispersion. La2O3 dispersion reduced the oxidation rate slightly, but it intensified the scale adhesion more effectively than Y2O3 dispersion.
EPMA observation of the scale revealed that the scale generally consisted of Cr2O3 layer and internally oxidized layer of Al2O3. The amounts of Ti and Ni in the Cr2O3 layer were higher in the straight alloy than in these dispersion alloys. The scale formed on the Y2O3 dispersion alloy, which showed the smallest mass gain by oxidation, consisted of the outer most layer of TiO2, the Cr2O3 intermediate layer containing almost no Ti, and the Al2O3 inner layer.View full abstractDownload PDF (3777K)
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