Role of Interfacial Coherency on Creep Behavior of FCC/BCC High-Entropy Alloy Multilayers

TL;DR

This paper studies how interface coherency affects the creep resistance of high-entropy alloy multilayers, revealing that semicoherent interfaces offer the best performance.

Contribution

The study establishes a direct link between interface coherency and creep mechanisms in HEA multilayers, enabling better design of creep-resistant coatings.

Findings

Semicoherent interfaces (λ = 16 nm) show highest creep resistance via atomic diffusion or interface slip.

Coherent interfaces (λ = 8, 32, and 80 nm) exhibit dislocation slip-dominated creep.

Interface coherency dictates the transition between diffusion and dislocation-mediated deformation.

Abstract

High-entropy alloy (HEA) multilayers represent a promising class of advanced coating materials due to their superior mechanical properties, corrosion resistance, and irradiation tolerance. However, the specific role of interface coherency on the creep behavior of HEA multilayers remains unclear. In this work, FCC/BCC Al-Cr-Fe-Ni HEA multilayers with different coherency were prepared by precisely controlling the modulated period (λ) via RF magnetron sputtering. Their room-temperature creep properties were systematically investigated through nanoindentation under different loading rates. The results reveal a strong dependence of creep resistance and deformation mechanisms on the interface coherency. HEA multilayers with semicoherent interfaces (λ = 16 nm) exhibit the highest creep resistance, where creep is primarily mediated by atomic diffusion or interface slip. In contrast, samples dominated by coherent interfaces or grain boundaries (λ = 8, 32, and 80 nm) demonstrate dislocation slip-dominated creep. This work elucidates how interfacial coherency dictates the transition between diffusion-mediated and dislocation-mediated creep mechanisms in HEA multilayers, providing critical insights for the design of next-generation creep-resistant nanostructured coatings.

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