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Volume 19, Issue 2
Displaying 1-5 of 5 articles from this issue
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[in Japanese], [in Japanese], [in Japanese]1972 Volume 19 Issue 2 Pages 32-42
Published: July 25, 1972
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (670K) -
Jiro Shibata, Shigenori Tanabe1972 Volume 19 Issue 2 Pages 43-49
Published: July 25, 1972
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn order to investigate the effect of silicon on the mechanical properties of sintered iron compacts, 1-4%Si were added to iron compacts, and W and Mo were also added to Fe-3%Si compacts, which showed the improved mechanical properties. They were compacted and sintered by the single-press and sinter techniques, by the double-press and sinter techniques and studied of various mechanical properties. The results were summarized as follows.
(1) Generally, the addition of Si to iron compacts increased the hardness and the tensile strength, however decreased the elongation of the compacts sintered at 1120°C.
(2) In the case of sintering at 1220 and 1300°C, their densification was remarkably accelerated above 2%Si, and therefore gave not only a high tensile strength, but also a high elongation. But the elongation decreased at 4%Si.
(3) The sintered Fe-3%Si compacts, when W and Mo were added, showed the improved mechanical properties. The elongation, however, decreased above 7%W and 5%Mo because of the precipitation of the compounds, namely Fe2W and Fe2Mo.
(4) The double-press and sinter techniques generally gave higher strengths than the single-press and sinter techniques, although at high temperatures there were only slight differences between both techniques.View full abstractDownload PDF (4689K) -
Takashi Daikoku, Fujimitsu Masuyama, Takao Mori1972 Volume 19 Issue 2 Pages 50-58
Published: July 25, 1972
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe authors made on effort to develop the material having superior elevated temperature properties by applying dispersion strengthening and liquid-phase sintering techniques in tile sintering of 12%Cr maraging steel powder, and the results obtained were as follows:
(1) Addition of a small amount of ferro-titanium alloy powder, which yields liquid phase at the sintering temperature, is effective for the improvement of the sintering characteristics of 12%Cr maraging steel powder.
(2) Sintered 12% Cr maraging steel with dispersed γ-Al2O3 exhibiting high creep rupture strength at the temperature of 550°C could be obtained. This sintered material has a superior creep rupture strength compared with similar sintered 13 CrMoTi steel examined separately.View full abstractDownload PDF (6139K) -
Hiroyasu Mitani, Masaru Yokota1972 Volume 19 Issue 2 Pages 59-66
Published: July 25, 1972
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn order to investigate the mechanism of thermal expansion during heating the Cu-Zn binary mixed powder compacts containing up to 90 wt% Zn, their dimensional changes were measured continuously by the differential dilatometer. The phase changes and the diffusion behabior during heating were determined by the differential thermal analysis and by the line analysis of the X-ray microanalyser, and the results obtained were summarized as follows.
All the specimens expanded gradually from 200°C to 419°C on the heating process, corresponding to the amount of the γ (Cu5Zn8)-phase formed through the zinc evaporation. However, just above the Zn-melting point of 419°C the amount of the γ-phase increased remarkably, and then the β-phase was produced by the interdiffusion between the γ- and the α-phase, where the spaces of the molten zinc which diffused into the γ- and the β-phase were abruptly replaced by the exuvial cavities, corresponding to the amount of the abnormal expansion above 419°C. The amount of the abnormal expansion increased with increasing zinc content up to 60 wt% Zn in the compact, but over this content, decreased with increasing zinc content, where the content of 60 wt% Zn coincides with the chemical composition of the γ-phase.
Consequently, it can be confirmed that the γ-formation induces the swelling of Cu-Zn compacts during heating process.View full abstractDownload PDF (2163K) -
Kozi Hayashi, Yasunori Fuke, Hisashi Suzuki1972 Volume 19 Issue 2 Pages 67-71
Published: July 25, 1972
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSThe grain size of WC-20%Co alloy affected by the addition carbides such as TiC, VC, Cr3C2, ZrC, NbC, Mo2C, HfC and TaC was in detail investigated. Specimens were sintered mainly at 1400°C for 1 hr. The mean grain size of starting WC powder was about 0.6μ.
Results obtained were as follows: (1) When the liquid phase was saturated by the addition carbides at sintering temperatures, the restriction effect of VC on the grain growth of WC was the largest, followed by Mo2C, Cr3C2, NbC, TaC, TiC, ZrC(≅HfC). In this case, there existed a strong correlation. between the restriction effect of addition carbides and the solubility limit in the liquid phase (or the formation free energy). (2) On the other hand, when the liquid phase contained a certain amount of dissolved metals of addition carbides, i.e., about 1.5at% for the starting Co, the effectiveness was in the following order; VC>NbC>TaC>TiC>Mo2C>Cr3C2>ZrC≅HfC. (3) Considering the restriction effect and the shape of carbides precipitated, VC addition was considered to be the most suitable for the grain growth inhibitation of WC, followed by Cr3C2, NbC and TaC.View full abstractDownload PDF (2010K)
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