Ultrastrong ductile and stable high-entropy alloys at small scales

TLDR

Refractory high‑entropy alloys exhibit superior high‑temperature mechanical performance but are typically brittle and poorly formable at room temperature. The study aims to develop a fabrication strategy for thin‑film and pillar forms of refractory HEAs with highly textured, columnar nanograins. The approach produces strongly textured, columnar, nanometre‑sized grains in the thin films and pillars, enabling the desired mechanical behavior. Resulting micro‑ and nano‑pillars achieve ~10 GPa yield strength, >30 % compressive plastic strain, and retain stability after 3 days at 1,100 °C, positioning them as promising materials for high‑stress, high‑temperature devices.

Abstract

Refractory high-entropy alloys (HEAs) are a class of emerging multi-component alloys, showing superior mechanical properties at elevated temperatures and being technologically interesting. However, they are generally brittle at room temperature, fail by cracking at low compressive strains and suffer from limited formability. Here we report a strategy for the fabrication of refractory HEA thin films and small-sized pillars that consist of strongly textured, columnar and nanometre-sized grains. Such HEA pillars exhibit extraordinarily high yield strengths of ∼ 10 GPa--among the highest reported strengths in micro-/nano-pillar compression and one order of magnitude higher than that of its bulk form--and their ductility is considerably improved (compressive plastic strains over 30%). Additionally, we demonstrate that such HEA films show substantially enhanced stability for high-temperature, long-duration conditions (at 1,100 °C for 3 days). Small-scale HEAs combining these properties represent a new class of materials in small-dimension devices potentially for high-stress and high-temperature applications.