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

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 strainhardened features helps the cracks to avoid catastrophic growth and percolation. Our self-buffering herringbone material yields an ultrahigh uniform tensile elongation (similar to 50%), three times that of conventional nonbuffering EHEAs, without sacrificing strength.

Automated summary

The study demonstrates a directionally solidified eutectic high-entropy alloy with a hierarchically organized herringbone structure that reconciles crack tolerance and high elongation. The self-buffering herringbone material achieves an ultrahigh uniform tensile elongation while maintaining strength.