分子ダイナミクスシミュレーションで金属の可塑性の限界を測る
Luis A Zepeda-Ruiz1, Alexander Stukowski2, Tomas Oppelstrup1
1Lawrence Livermore National Laboratory, Livermore, California, USA.
Nature
|September 28, 2017
まとめ
タンタルのような金属の可塑性は 通常 変位によって説明されます 超高張力率では,変形配列が支配的になり,金属は流体のように流れます.
科学分野:
- 材料科学
- コンピュータ材料科学
- 固体力学
背景:
- 金属の強度と可塑性は通常,材料の滑り込みを可能にする結晶格子における線形欠陥によって制御されます.
- 変位ダイナミクスモデルは一般的なメソスケールシミュレーションですが,すべての原子レベルの変形メカニズムを捉えることはできません.
- 全ての原子の動きを含む,物質の反応のより包括的な見方を提供します.
研究 の 目的:
- 極端な条件下で単結晶タンタルの可塑性の完全ダイナミックなアトミスティックシミュレーションを行う.
- 変位による可塑性の限界を特定し,これらの限界を超えた変形メカニズムを調査する.
- 変位滑りから他の変形モードへの移行を定量化します.
主な方法:
- 大量単結晶タンタルの完全ダイナミックな原子模擬を用いた.
- [001]結晶軸に沿って,超高張力,常圧,温度,および張力率で圧縮されます.
- 大規模なシミュレーションデータ (85~340 nm,1 ns~1 μs) を分析するために,in situ 計算顕微鏡を用いる.
主要な成果:
- 変位だけでは,一定のストレスの限界を超えた機械的負荷を軽減することはできません.
- 変形配列は,これらの制限条件下で支配的なプラスチック反応メカニズムとして出現します.
- 制限値を下回ると,タンタルは安定状態のプラスチックの流れを示し,結晶の整合性を維持しながら粘着性のある液体のように振る舞います.
結論:
- 原子学的シミュレーションは,超高張力率でのタンタルの可塑性における重要なメカニズムであることを示しています.
- タンタルは固体の状態で,結晶構造を保持しながら,固体の状態で流れる.
- これらのダイナミックな反応を理解することは 極端な負荷条件下での物質の振る舞いを予測するのに不可欠です
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