Dual-Nano Composite\nDesign with Grain Boundary Segregation\nfor Enhanced Strength and Plasticity in CoCrNi-CuZr Thin Films

Enhancing both strength and plasticity simultaneously\nin nanostructured\nmaterials remains a significant challenge. While grain refinement\nis effective in increasing strength, it typically leads to reduced\nplasticity due to localized strain. In this study, we propose a novel\ndesign strategy featuring a dual-nano composite structure with grain\nboundary segregation to enhance the deformation stability of nanostructured\nmaterials. This strategy is demonstrated using a CoCrNi-CuZr multiprincipal\nelement alloy film, which shows a dual-nano composite structure with\nhigh-density nanotwins and crystalline–amorphous nanocomposite,\nalong with elemental segregation at the columnar grain boundaries.\nOur strategy achieves homogeneous plastic deformation in a (CoCrNi)<sub>91</sub>(CuZr)<sub>9</sub> thin film, an 18% increase in strength\ncompared to nanocrystalline CoCrNi, and a 67% increase compared to\namorphous CuZr thin films. These results provide valuable insights\ninto designing high-strength, ductile alloys through the engineering\nof dual-nano composite structures.