| Project/Area Number |
08455310
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Composite materials/Physical properties
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| Research Institution | Nagoya University |
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Principal Investigator |
MIYATA Takashi Nagoya University, Materials Sci. & Eng., Prof., 工学研究科, 教授 (20023228)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAJIMA Katsumi Nagoya University, Materials Sci. & Eng., Res.Assoc., 工学研究科, 助手 (00273269)
TAGAWA Tetsuya Nagoya University, Materials Sci. & Eng., Asoc.Prof., 工学研究科, 講師 (00216805)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,700,000 (Direct Cost: ¥7,700,000)
Fiscal Year 1997: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1996: ¥5,900,000 (Direct Cost: ¥5,900,000)
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| Keywords | Particle reinforced composites / TiC / Ti composite / TiB / Ductile fracture / Fatigue crack growth / Fatigue strength / Rectangular element model / Particle cracking |
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| Research Abstract |
Effects of aspect ratio and machanical properties of particle reinforcement on ductility, static and fatigue strength of in-situ type of particle reinforced composites were invetigated. Mechanical models for ductile fracture for metallic materials and the rectangular particle element model for composites were applied for quantitative analysis. Materials tested were titanium matrix composites reinforced with TiC and TiB particles produced by the in-situ vacuum arc remelting process, andTi-6A1-4V alloy. TiC particles are spherical and TiB are whiskerlike particles. The effect of stress triaxiality on ductile fracture process and ductility were invetigated using smooth and notched round bar tensile specimens. Particle cracking which is observed at early stage of deformation is the first nucleation site of micro-void, resulting significant degaradation in ductility. Debonding at interface between particle and matrix wasn't observed in both materials regardless of the presence of notch. Mechanical models and finite element calculation presume the cracking of ceramic particles at the plastic yielding of matrix. Strengthening of interface doesn't improve the ductility.
Fatigue crack growth rate in the TiC/Ti composite is higher than that of Ti-6A1-4V alloy, whereas the TiB/Ti composite shows high resistance to fatigue crack growth due to particle bridging and deflection of crack. However, fatigue strength in smooth condition in which crack nucleation process governs fatigue life, is highly deteriorated by particle cracking. High strength of interface causes high degradation in fatigue strength of titanium matrix composites. Cyclic loading to the titanium matrix results cyclic softening of matrix and it causes particle cracking. The results in the present work indicate that higher fatigue strength than the matrix can not be expected in the titanium matrix composites, while the alminium matrix composites often show higher fatigue strength than that of alminium alloys.
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