| 研究課題/領域番号 |
18K14024
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| 研究機関 | 東北大学 |
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研究代表者 |
崔 玉傑 東北大学, 金属材料研究所, 学術研究員 (30796214)
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| 研究期間 (年度) |
2018-04-01 – 2020-03-31
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| キーワード | Magnesium alloys / Twin boundary mobility |
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| 研究実績の概要 |
Twin in magnesium (Mg) alloys can either grow or shrink, and the reciprocating movements of twin boundaries have a significant effect on Mg mechanical properties. Tailoring twin boundary mobility is imperative to obtain the required properties for Mg and its alloys.
The effects of pre-strain and alloying elements on twinning behavior in Mg alloys were investigated. Owing to the growth and coalesce of small twins, average twin size and twin area fraction increase with enhanced pre-strain. Solute atoms impede twin boundary motion. Twin size decreases with increased alloying element concentration.
Furthermore, the influences of pre-strain on twin boundary mobility in pre-compressed Mg were evaluated. Both friction and back stress for twin growth or detwinning increases with increasing pre-strain. This is mainly because of the restriction from increased dislocations and interactions with other boundaries.
Owing to lower dislocation density and less restriction from other boundaries, smaller twins in Mg subjected to 2% compressive strain exhibit higher twin boundary mobility than larger twins in pre-4% and pre-8% compressed Mg. Altering twin size and dislocation density by pre-strain is an effective way to tailor twin boundary mobility, providing a basis for developing new industrial Mg alloys.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
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理由
The microstructure observations and mechanical tests were carried out as scheduled. The twin boundary mobility was evaluated by combining the change of yield strength during compression and tension, and microstructure observations by in-situ electron back-scattered diffraction.
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| 今後の研究の推進方策 |
Based on the research plan, the influences of alloying elements, including Al, Mn, Gd on the twin boundary mobility will be evaluated by compressive and tensile tests on pre-compressed Mg alloys. Based on the compressive and tensile yield strength, the friction stress and back stress for twin boundary motion can be calculated to evaluate TBM quantitatively.
The twin evolution will be analyzed by in-situ EBSD observations. Moreover, TEM experiments will be carried out to clarify the interaction between twin boundary and solute atoms. Quantitative relationship between twin boundary mobility and various factors will be established in Mg alloys. The optimized technology for tailoring twin boundary mobility will be proposed for developing Mg alloys with high damping capacity and high strength.
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