Toughness enhancement by massive dislocation absorption at the crack front

• 成果类型: Article
• 署名作者: Zhang, Jiazhi; Yu, Qin; Tian, Jiazhuang; Yang, Shanglu; Zuo, Xunwei; Li, Ying; Chen, Nailu; Rong, Yonghua; Ritchie, Robert O.; Lu, Jian
• 署名单位: Chinese Academy of Sciences; Shanghai Institute of Optics & Fine Mechanics, CAS; University of California System; University of California Berkeley; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; Shanghai Jiao Tong University; City University of Hong Kong; City University of Hong Kong; City University of Hong Kong; Shenzhen Research Institute, City University of Hong Kong
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14490
• DOI: 10.1073/pnas.2511830122
• 发表日期: 2025-09-16
• 关键词: austenitic stainless-steel; high-entropy alloys; in-situ tem; fracture-toughness; high-strength; mechanical-properties; ductility enhancement; retained austenite; microstructure; carbon

摘要

Low-cost yet high-performance structural materials have been invariantly sought for modern engineering applications. However, due to the localized stress concentration induced by a high Peierls-Nabarro stress and limited dislocation mobility, increasing material strength usually comes at the expense of ductility and toughness, resulting in a trade-off between strength-ductility/strength-toughness. Here, we report an anomalous phenomenon of dislocation absorption at the crack front, which is unlike typically observed dislocation emission at the crack tip, in a heterogeneous plain steel consisting of tempered lath martensite embedded with stable carbon-enriched retained austenite. The continuous absorption of dislocations emitted from the tempered martensite into the tough austenite significantly alleviates the localized stress concentration, and as such retards crack propagation in the tempered martensite matrix. This allows the plain high-carbon low-alloyed steel subjected to simple quenching-partitioning-tempering processes to achieve remarkable properties comprising a multiplication of strength and elongation over 50 GPa% with an exceptionally high fracture toughness over 130 MPam1/2. The toughening strategy based on this mechanism provides a promising route for developing cost-effective plain steels with ultrahigh strength, ductility, and toughness that is a persistent pursuit in the steel industry.