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Volume 32, Issue 6
Displaying 1-6 of 6 articles from this issue
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Kazuhisa Shobu, Tadahiko Watanabe1985 Volume 32 Issue 6 Pages 215-218
Published: August 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThis paper describes the effects of sintering conditions such as amount of TiB2 and temperature on the mechanical properties of TiN-TiB2 compacts, and describes the hot hardness, the fracture toughness Ktc and the resistance of oxidation of TiN-TiB2 compacts. The results were as follows:
1. TiN-TiB2 compacts, which contained 30-60 wt% TiB2, have high density and high transverse rupture strength. It is thought that the reasons of the high transverse rupture strength are reduced by the restraining of TiN grain growth and the high density.
2. TiN-30%TiB2 compacts have the transverse rupture strength of 700 MN/m2, the porosity of 0.34 vol%, the Vickers hardness of 1800 kg/mm2 at R.T. and of 990 kg/mm2 at 1233 K, and the fracture toughness K1c of 3 MPa⋅m1/2.View full abstractDownload PDF (1214K) -
Hisashi Suzuki, Hideaki Matsubara, Masaya Asano1985 Volume 32 Issue 6 Pages 219-223
Published: August 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe microstructures of TiC0.5N0.5-19%Mo2C-23%Ni alloy sintered at 1723 K in vacuum or in various nitrogen pressures (PN2) were mainly studied.
It was found that Mo2C phase crystallized during cooling after sintering, when the alloy was sintered in the atmosphere with low PN2 (≤3 kPa), and the amount of the phase increased with lowering PNN2⋅The phase did not crystallize when the carbon content of the alloy was slightly increased. The reason why the phase was produced or not according to PN2and carbon content of the alloy was discussed. The transverse-rupture strength of the alloy was examined in relation to these two factors affecting the microstructures.View full abstractDownload PDF (4939K) -
Koji Hayashi, Yoshihiro Onomura1985 Volume 32 Issue 6 Pages 224-228
Published: August 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe solidification structures of the liquid phase formed during sintering, such as domain structures (crystal grain) of Mg2SiO4 and MgAl2O4 phases, and the room temperature mechanical properties of Si3N4-(10-20)mo1%MgO-5.5 mo1% Al2O3 ceramics were investigated as a function of cooling rate (0.017-1Ks-1) after sintering. The sintering temperature, time and atmosphere were 1973 K, 3.6 ks and nitrogen of 0.1 MPa, respectively.
When the cooling rate became larger, the domain structures of the Mg2SiO4 and MgAl2O4 phases became finer and at the same time the amount of both phases decreased (the amount of glassy phase probably increased). The transverse-rupture strength of the ceramics increased with increasing cooling rate. This result would be attributed to both the improved toughness of ceramics caused by the refinement of microstructure and the decreased size of defect (pore) acting as a fracture source. The microstructural heterogeneous surface layer of sintered compact and the hardness were also varied by the cooling rate.View full abstractDownload PDF (2559K) -
Kiichi Oda, Tetsuo Yoshio, Kazuo O-oka, Fumikazu Kanamaru1985 Volume 32 Issue 6 Pages 229-231
Published: August 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSHigh coercivity SrFe12O19 particles were prepared by the glass-ceramic method using the glass with composition y=1 in the system 46.94[(1-y)BaO⋅ySrO]⋅7.14B2O3⋅11.43SiO2.24.49Fe2O3 (mo1%), and plastic-magnets were fabricated with the obtained particles.
SrFe12O19 particles (≈0.3μm in diam.) were obtained by leaching the sample after a heat treatment of the glass (y=1) at 875°C for 5 hr. The particles showed very high coercive force of 6080 Oe and σs=52 emu/g.
SrFe12O19 plastic-magnet fabricated by the roll method consisted of random assembly. Values of magnetic properties were BHC=1030 Oe, Br=1150G, and (B⋅H)max=0.3 M G⋅Oe, however a SrFe12O19 plastic-magnet fabricated by the injection molding under applying magnetic field exhibited slightly preferred orientation with the values of BHC=1551 Oe, Br=1743 G, and (B⋅H)max=0.7 M G⋅Oe.View full abstractDownload PDF (1327K) -
Morphology Change of γ' Precipitates during Recrystallization and CreepMasao Morishita, Fusaki Koshiishi, Hiroshi Nagai, Keiichiro Shoji1985 Volume 32 Issue 6 Pages 232-236
Published: August 25, 1985
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMorphology change of γ' precipitates in nickel-base superalloy IN-100 prepared by liquid phase sintering and swaging was investigated during recrystallization and creep (1323 K, 66.6 MPa).
The results obtained were as follows:
(1) In the swaged specimens, large-sized and cellular γ' precipitates appeared behind the migrating boundary of recrystallized grains in a similar manner as that in discontinuous precipitation. On the other hand, uniform and fine γ' precipitates appeared in the strain-free specimens subjected to solution treatment after swaging.
(2) The large and cellular γ' precipitated at grain boundaries parallel to the tensile stress axis during creep. However, this orientation became indistinct with decreasing y-grain size.View full abstractDownload PDF (2576K) -
Shiro Kohara, Kiyohiko Tatsuzawa1985 Volume 32 Issue 6 Pages 237-242
Published: August 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSintering behavior of Fe-Cu-Ni compacts prepared by electroless plating on iron powder was studied by means of the dilatometric method and electron probe micro analysis. The copper growth in the compacts of plated powder was markedly reduced during heating in the temperature range of gamma iron, compared with the case of mixed powder. The following mechanism was proposed for the decrease in copper growth in the compacts of plated powder. The nickel-copper alloy layer formed on the surface of iron particles retards the diffusion of copper to the surface of iron during heating. This alloy layer also prevents liquid copper from contacting with the surface of iron particles directly, and finally absorbs liquid copper to form a solid solution in the temperature range above the melting point of copper. Therefore, the decrease in grain boundary diffusion of copper in the iron particles brings about the reduced copper growth, compared with the case without making the alloy layer.View full abstractDownload PDF (4879K)
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