Influence of chemical composition on nanoindentation behavior of Zr-Al-Ni-Cu metallic glasses: An experimental and molecular dynamics approach

• Hardness and elastic modulus of Zr x (Al 0.25 Ni 0.25 Cu 0.5 ) 100− x bulk metallic glasses decrease with increasing Zr content. • Molecular dynamics simulations reproduce experimental nanoindentation load–displacement behavior. • Plasticity initiates via shear transformation zones beneath the indenter. • Lateral atomic flow and pile-up indicate localized and homogeneous deformation. • Higher Zr content increases free volume and reduces atomic packing efficiency. A combined experimental and molecular dynamic simulation method was employed to reveal the nanoindentation behavior and atomic-scale deformation mechanisms of Zr x (Al 0.25 Ni 0.25 Cu 0.5 ) 100− x bulk metallic glasses. Bulk metallic glass samples were prepared by arc melting followed by Cu mold suction casting, and their fully amorphous structure was verified by X-ray diffraction and differential scanning calorimetry. Nanoindentation experiments revealed a monotonic decrease in hardness and elastic modulus with rising Zr content, highlighting the compositional dependence of mechanical properties. Molecular dynamics simulations using a Berkovich indenter reproduced the experimental load–displacement behavior and provided atomic-level insights. Von Mises shear strain distributions indicated that shear transformation zones nucleate the indenter and propagate asymmetrically due to the inherently disordered atomic structure. Atomic displacement analysis further revealed pronounced lateral flow ad material pile-up, indicating that plastic deformation occurs via localized shear flow facilitated by atomic rearrangements. These findings establish a direct correlation between chemical composition, atomic-scale structure, and mechanical response, offering guidance for the design and optimization of high-performance Zr-based BMGs.