Dual-Nano Composite Design with Grain Boundary Segregation for Enhanced Strength and Plasticity in CoCrNi-CuZr Thin Films

Enhancing both strength and plasticity simultaneously in nanostructured materials remains a significant challenge. While grain refinement is effective in increasing strength, it typically leads to reduced plasticity due to localized strain. In this study, we propose a novel design strategy featuring a dual-nano composite structure with grain boundary segregation to enhance the deformation stability of nanostructured materials. This strategy is demonstrated using a CoCrNi-CuZr multiprincipal element alloy film, which shows a dual-nano composite structure with high-density nanotwins and crystalline-amorphous nanocomposite, along with elemental segregation at the columnar grain boundaries. Our strategy achieves homogeneous plastic deformation in a (CoCrNi)₉₁(CuZr)₉ thin film, an 18% increase in strength compared to nanocrystalline CoCrNi, and a 67% increase compared to amorphous CuZr thin films. These results provide valuable insights into designing high-strength, ductile alloys through the engineering of dual-nano composite structures.