Formation of hierarchically structured martensites in pure iron with ultrahigh strength and stiffness

• 成果类型: Article
• 署名作者: Gu, Chao; Chen, Haiyan; Zhao, Yusheng; Wang, Shanmin
• 署名单位: Southern University of Science & Technology; State University of New York (SUNY) System; Stony Brook University; Eastern Institute of Technology, Ningbo
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12545
• DOI: 10.1073/pnas.2408119121
• 发表日期: 2024-10-15
• 关键词: mechanical-properties; pressure; steel; TRANSFORMATION; nucleation; hardness; diamond; ductile

摘要

Strong steels are primarily fabricated by introducing spatial obstacles (e.g., stacking faults and precipitates) that inhibit dislocation slips under stress to achieve high strength. However, for most low- carbon steels, such obstacles are difficult to form mainly because the martensitic transition is kinetically unfavorable by conventional methods, which precludes the attainment of high- strength materials in these steels with low solute contents. Here, we report an innovative high- pressure preparation of martensitic pure Fe with involving nano- effect, which leads to the formation of ultrastrong bulk iron with exceptionally high yield strength, ultimate strength, and hardness of 2.9 GPa, 3.7 GPa, and 9.0 GPa, respectively, exceeding those of high- speed steels. Such extraordinary mechanical properties are closely attributed to its high- density martensites with unique multiscale hierarchical structures formed due to complex phase transitions under pressure.