Hierarchical crack buffering triples ductility in eutectic herringbone high-entropy alloys

Shi, P. and Li, R. and Li, Y. and Wen, Y. and Zhong, Y. and Ren, W. and Shen, Z. and Zheng, T. and Peng, J. and Liang, X. and Hu, P. and Min, N. and Zhang, Y. and Ren, Y. and Liaw, P.K. and Raabe, D. and Wang, Y.-D.

Volume: 373 Pages: 912-918
DOI: 10.1126/science.abf6986
Published: 2021

In human-made malleable materials, microdamage such as cracking usually limits material lifetime. Some biological composites, such as bone, have hierarchical microstructures that tolerate cracks but cannot withstand high elongation. We demonstrate a directionally solidified eutectic high-entropy alloy (EHEA) that successfully reconciles crack tolerance and high elongation. The solidified alloy has a hierarchically organized herringbone structure that enables bionic-inspired hierarchical crack buffering. This effect guides stable, persistent crystallographic nucleation and growth of multiple microcracks in abundant poor-deformability microstructures. Hierarchical buffering by adjacent dynamic strain–hardened features helps the cracks to avoid catastrophic growth and percolation. Our self-buffering herringbone material yields an ultrahigh uniform tensile elongation (~50%), three times that of conventional nonbuffering EHEAs, without sacrificing strength. © 2021 American Association for the Advancement of Science. All rights reserved.

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