Wang Feng, Song Miao, Elkot Mohamed N, Yao Ning, Sun Binhan, Song Min, Wang Zhangwei, Raabe Dierk
State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China.
Max Planck Institute for Sustainable Materials, Düsseldorf, Germany.
Science. 2024 May 31;384(6699):1017-1022. doi: 10.1126/science.ado2919. Epub 2024 May 30.
Precipitates are crucial for crafting mechanically strong metallic materials. In this work, we report the dislocation cutting of B2 (ordered body-centered cubic) nanoprecipitates, typically considered nonshearable intermetallics, in a lightweight compositionally complex steel during cryogenic tensile loading. Shearing is enabled by the high strength level for dislocation glide within the austenitic matrix, attributed to the substantial strengthening from subnanoscale local chemical ordering zones and the pronounced solid solution strengthening from the multiprincipal elements in the matrix. This mechanism not only harnesses the intense strengthening and strain hardening provided by otherwise impenetrable brittle nanoprecipitates but also introduces ductility through their sequential shearing with ongoing deformation. Our steel thus showcases ultrahigh cryogenic tensile strength up to 2 gigapascal at a remarkable tensile elongation of 34%. This study reveals a new strategy for designing high-performance structural materials.
析出物对于制造机械性能强大的金属材料至关重要。在这项工作中，我们报告了在低温拉伸加载过程中，在一种轻质成分复杂的钢中，B2（有序体心立方）纳米析出物（通常被认为是不可剪切的金属间化合物）的位错切割现象。由于奥氏体基体中位错滑移的高强度水平，使得剪切成为可能，这归因于亚纳米级局部化学有序区域的显著强化以及基体中多主元的明显固溶强化。这种机制不仅利用了原本不可穿透的脆性纳米析出物所提供的强烈强化和应变硬化，还通过它们在持续变形过程中的顺序剪切引入了延展性。因此，我们的钢在高达34%的显著拉伸伸长率下，展现出高达2吉帕斯卡的超低温拉伸强度。这项研究揭示了一种设计高性能结构材料的新策略。
