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Determining the Mechanical Strength of Ultra-Fine-Grained Metals
Published on: November 22, 2021
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超細粒度金属の高圧強化
Xiaoling Zhou1,2,3, Zongqiang Feng4, Linli Zhu5,6
1Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai, China.
Nature
|February 26, 2020
まとめ
ホール-ペッチ関係は15nm以下で崩壊し,軟化を引き起こします. この研究は,ニッケルで3nmの粒径まで継続的な強化を示し,組み合わせた硬化メカニズムによって超高性能を達成しています.
科学分野:
- 材料科学
- ナノテクノロジー
- 機械工学
背景:
- ホール・ペッチ関係では,粒子の大きさが減少すると,金属の強度が増加すると予測される.
- この関係は,臨界粒度 (10−15 nm) 以下の分解により,変形メカニズムが変化したため,材料が柔らかくなります.
- 柔らかくなるのを食い止めるための以前の方法には 穀物の境界を安定させることが含まれていました
研究 の 目的:
- 高圧下での3 nmまでの粒径を持つ純ニッケルの機械的振る舞いを調査する.
- 継続的な強化が超小粒度で発生するかどうかを判断し,確立されたホール-ペッチ分解に挑戦する.
- ナノ結晶金属の強さを高める 基礎的な強化メカニズムを特定する.
主な方法:
- 放射性X線 difraksionと組み合わせたダイヤモンドアンビルセルを使用して,収量ストレスと変形テクスチャのインシット追跡.
- 粒子の大きさは200 nmから3 nmまで.
- シミュレーションと伝送電子顕微鏡を用いた補足分析.
主要な成果:
- 粒子の大きさが200nmから3nmに減少するにつれて,ニッケルサンプルで継続的な強化が観察されました.
- 強化は20 nm未満の粒度で強化され,ホール-ペッチ関係の予想される分解とは対照的です.
- 3nm粒径のニッケルで約4.2GPaの収縮強度と10.2GPaの最大流動張力を達成した.
- 黄金とパラジウムサンプルで同様の強化パターンが観察されました.
結論:
- ハル・ペッチ関係が克服され,3 nmの粒度まで継続的な強化が示される.
- 3nm粒径のニッケルの超高強度は,変位硬化と抑制された粒径境界の可塑性によるものです.
- これらの発見は,粒子のサイズと変形メカニズムを正確に制御することによって,超強い金属を設計するための経路を提供します.
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