1988 Fiscal Year Final Research Report Summary
A Baic Study of Strengthening of Polycrystalline Magnetic Materials
| Project/Area Number |
61550518
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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 |
金属材料(含表面処理・腐食防食)
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
WATANABE Tadao Research Associate, Faculty of Engineering, Tohoku Univ.,, 工学部, 助手 (40005327)
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| Project Period (FY) |
1986 – 1988
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| Keywords | Grain Boundary Design / Control of Brittleness and Intergranular Fracture / Grain Boundary Character Distribution (GBCD) / Magnetic Annealing / 磁気焼鈍効果 / SEM-ECP / 急冷凝固 / Fe-6.5mass%Si / 集合組織と粒界 / 低エネルギー粒界 |
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| Research Abstract |
In order to improve mechanical Properties of polycrystalline megnetic materials which are normally show a significant brittleness associated with intergranular fracture, the possibility of the control of intergranular fracture has been studied according to the concept of grain boundary design recently proposed by the present investigator. The type and frequency of grain boundaries, so called grain boundary character distribution (GBCD) has been investigated in several ferromagnetic iron alloys (iron-cobalt and iron-silicon alloys) produced by different fabrication methods. Firstly, the grain boundary character distribution (GBCD) was determined for iron-10%cobalt alloy polycrystals which were produced by annealing in the magnetic field up to 0.5T. It was found that It was found that the frequency of low-angle boundaries increases linearly with increasing the magnetic field strngth. Almost four times higher frequency (7.8%) of low-angle boundaries was observed for the specimen produce b
… More
y magnetic annealing at 0.5T than that for the specimen without magnetic annealing. Thus magnetic annealing has been proved to be useful for controlling the GBCD in ferromagnetic polycrystals.
In the present work, the GBCD for rapidly solidified and annealed iron-6.5mass%Si alloy ribbons with {100} or {110} texture, was stueied in order to reveal the origin of high ductility of the ribbone. extremely high frequency ( =45% ) of low-energy boundaries such as low-angle ( 1) boundaries and low coincidence boundaries, was observed. the observed high ductility of the ribbons is attributed to the presence of high frequency of low-energy boundaries which are resistant to intergranular fracture. the inverse cubic root dependence of the frequency of coincidence boundaries was first found. The values of coincidence boundaries which occurred preferentially in {100} or {110} textured riibons, can be predicted from coincidence orientation relationship for <100> or <110> rotation. It has been shown that the grain boundary character distribution (BGCD) can be manupilated in order to endow polycrystalline magnetic materials with desirable properties, particularly to control their brittleness caused by intergranular fracture, according to the concept of grain boundary design recently proposed by the present investigator. Less
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