1991 Fiscal Year Final Research Report Summary
Fundamental Research on Very High Strain-rate-deformation in Hard-forming Materials of Composites, Intermetallics and Ceramics.
| Project/Area Number |
01550537
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属加工(含鋳造)
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| Research Institution | University of Osaka Prefecture |
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Principal Investigator |
TANIMURA Sinji Univ. of Osaka Prefecture, College of Engrg., Professor, 工学部, 教授 (30081235)
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| Co-Investigator(Kenkyū-buntansha) |
KAIZU Kouichi Univ. of Osaka Prefecture, College of Engrg., Research Assoc., 工学部, 助手 (50177317)
HIGASHI Kenji Univ. of Osaka Prefecture, College of Engrg., Assoc. Professor, 工学部, 助教授 (50173133)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Composites / Intermetallics / Ceramics / Hard-forming materials / High strain rate deformation / High temperature / Strain-rate sensitivity / High strain rate superplasticity |
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| Research Abstract |
The development of new materials, through recent advances in technology, has led to new forming processes in hard-forming materials of composites, intermetallics and ceramics. One of them is superplatic forming, which showed both large elongations and high strain-rate sensitivities, has been limited in use because of its lower productive rate than an industrial one. On the ther hand, it was reported that some materials exhibited a high strain-rate sensitivity at extremely high strain rates over 1 s^<-1>. In this subject, high strain-rate deformation properties in hard-forming materials of composites, intermetallics and ceramics are investigated in a wide strain-rate range and temperatures. Low strain rate tensile tests (10^<-4>-1 s^<-1>) were performed with an instron machine, and intermediate strain rate tensile tests (1-300 s^<-1>) were performed with the hydraulic tensile testing machine, and the dynamic tensile tests (400-4000 s^<-1>) were performed using a split Hopkinson pressure
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bar system which incorporates a specific attachment. A large elongation of about 600% was obtained both in a Si_3N_<4w>/Al-Mg-Si composite at an initial strain rate of 2 x 10^<-1> s^<-1> and also in a Si_3N_<4p>/Al-Mg-Si composite at an extremely high strain rate of 2 s^<-1>. Furthermore, large elongations of more than 1000 % were obtained in the mechanically alloyed aluminum IN 9021 (Al-4.0wt%Cu-1.5wt%Mg-1.1wt%C-0.8wt%O) deformed at extremely high strain rates from 10 to 100 s^<-1>. The maximum elongation of 1250 % was recorded at 50 s^<-1> and 823 K. The optimum strain rate range in these new advanced aluminum alloys is three or four orders of magnitude faster than for the best of the conventional commercial alum inum alloys, such as Supral or 7475 alloys. Large elongations of more than 500 % are obtained at high strain rates between 5 and 100 s^<-1> for a mechanically alloyed 15 vol % SiCp/IN9021 aluminum composite tested at 823 K. It is clear that superplastic strain-rate increases with decreasing of grain size. From this relationship, the refinement of grains or sub-grains size is one of necessary and important to obtain the high strain-rate superplasticity. In future it might be possible that the predicted range of superplastic behavior in nano-phase materials by Sherby and Wadsworth would be achieved in mechanical alloyed materials with an optimum microstructural control. Less
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