Multiscale insights into the microstructure and mechanical behavior of Ag-doped Zr-based amorphous microwires

The effects of Ag-doping on the microstructure, thermal stability, and mechanical behavior of Zr 53.5 Cu 29.5- x Ni 5 Al 12 Ag x ( x = 0-7 at.%) amorphous microwires (AMWs) were systematically investigated through experimental characterization combined with multiscale simulations. The results demonstrate that appropriate Ag-doping significantly enhances the thermal stability and mechanical properties of Zr-based AMWs, with the Zr 53.5 Cu 27.5 Ni 5 Al 12 Ag 2 (Ag2) AMW exhibiting a larger supercooled liquid region of 53.5 K, higher enthalpy change of 55.81 J/g, ultimate tensile strength of 2630 MPa, hardness of 6.3 GPa, and elastic modulus of 104.4 GPa ab initio molecular dynamics (AIMD) simulations reveal that 2 at.% Ag-doping reduces atomic-scale structural heterogeneity through enhanced atomic packing efficiency, increased fractions of icosahedral-like local structures, strengthened Zr-Ni and Cu-Al atomic correlations, and enlarged medium-range order size. These atomic-scale features enhance structural stability, thereby contributing to the improved thermal stability of the Ag2 AMW. Furthermore, classical molecular dynamics (MD) simulations provide atomistic insights into the deformation mechanisms during tensile loading, demonstrating that the Ag2 AMW maintains dispersed shear transformation zone (STZ) activation and homogeneous shear deformation at high strains, which is consistent with a reduced tendency for shear localization and a delayed development of dominant shear bands. In contrast, excessive Ag-doping is associated with STZ aggregation and promotes shear localization. These findings provide multiscale insights into the relationship between structural characteristics and macroscopic mechanical behavior, offering guidance for the design of high-performance Zr-based AMWs.