Effects of grain size and zirconium concentration on mechanical properties of nanocrystalline copper grain boundary doping

CD Wu and HY Chen and MH Kuo, MOLECULAR SIMULATION, 50, 1183-1193 (2024).

DOI: 10.1080/08927022.2024.2387876

Alloying nanocrystalline Cu (nc-Cu) with immiscible elements (i.e. Zr) is a promising approach for reducing microstructural instability and inhibiting grain growth. Understanding the relationship between the grain size, Zr concentration, deformation, and mechanical properties of the nc-Cu-Zr system is essential for practical applications. Molecular dynamics simulations based on the many-body embedded-atom potential were used for the related analysis from an atomistic point of view. The grain size of nc-Cu was varied from 3 to 9 nm and the Zr concentration was varied from 0% to 7%. The simulation results show that doping Zr atoms into an nc-Cu system enhances tensile strength and ductility, but weakens compressive and shear strengths. Doping 1% Zr into nc-Cu greatly increases both ultimate tensile strength and ultimate tensile strain; the increase is insignificant for higher Zr concentrations (2% to 7%). For a given Zr concentration, the relationship between ultimate tensile strength and grain size is unclear. Grain boundary sliding dominates the elastic deformation mechanism of the nc-Cu-Zr system under tensile, compressive, and shear tests. Tensile fracture occurs faster for an nc- Cu-Zr system with a larger grain size.

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