Designing Maximal Strength in Nanolamellar Eutectic High-Entropy Alloys.

Abstract

Eutectic alloys have driven technological advancements for centuries, from early bronze tools that marked the dawn of metallurgy to high-performance soldering materials. Building on this legacy, eutectic high-entropy alloys (EHEAs) have recently emerged to push the boundaries of mechanical performance. However, the strength potential of EHEAs remains largely untapped, primarily because of limitations in cooling rates, posing a significant challenge to the development of ultra-strong bulk EHEAs. This study employs large-scale molecular dynamics simulations to uncover key insights into the design of EHEAs with exceptional mechanical performance. Simulations reveal that the maximum tensile strength occurs at a critical interphase boundary spacing, an order of magnitude larger than that observed in conventional alloys. Below this spacing, the governing mechanism shifts from the Hall-Petch strengthening to dislocation multiplication-mediated softening. Guided by the simulation insights, a tensile strength of 1.8 GPa is achieved for laser powder bed fusion-fabricated EHEAs. This strength approaches the theoretical limit and outperforms other state-of-the-art as-printed high-entropy alloys. This work not only establishes a viable pathway for designing ultra-strong EHEAs but also provides a promising avenue for addressing the long-standing challenge of developing high-performance as-printed materials for aerospace and other demanding applications.