STUDI PENGARUH KOMPOSISI MgZn TERHADAP KEKUATAN TARIK DAN TEKAN MENGGUNAKAN SIMULASI DINAMIKA MOLEKULER

Magnesium (Mg) is a lightweight metallic material with significant potential for various engineering applications due to its low density and favorable mechanical properties. However, the mechanical performance of magnesium can be further modified through alloying with other elements. This study aims to investigate the effect of Zn composition on the mechanical properties of MgZn alloys under tensile and compressive loading using molecular dynamics simulations. The compositions investigated were Mg₁₀₀, Mg₉₅Zn₅, Mg₉₀Zn₁₀, Mg₈₅Zn₁₅, and Mg₈₀Zn₂₀. The crystal structures were constructed based on the hexagonal close-packed (HCP) structure of magnesium by substituting Mg atoms with Zn atoms using Avogadro software. Structural optimization and mechanical simulations were subsequently performed using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), while structural evolution was analyzed and visualized using the Open Visualization Tool (OVITO). The tensile simulation results show that increasing the Zn content increases the elastic modulus from 50.26 GPa for Mg₁₀₀ to 64.76 GPa for Mg₈₀Zn₂₀. In contrast, the ultimate tensile strength (UTS) decreases from 5.14 GPa to 3.56 GPa, while the yield strength decreases from 3.37 GPa to 2.66 GPa. Under compressive loading, increasing the Zn content also increases the elastic modulus from 75.82 GPa to 92.18 GPa, whereas the ultimate compressive strength (UCS) decreases from 11.19 GPa to 5.15 GPa, and the yield strength decreases from 9.94 GPa to 4.52 GPa. Crystal structure analysis indicates that increasing the Zn content affects the evolution of the crystal structure during deformation, as evidenced by the partial transformation of the HCP structure into an amorphous structure. Therefore, the addition of Zn to Mg alloys increases material stiffness but tends to reduce their tensile and compressive strength under the simulated loading conditions.

Keywords: Magnesium, Zinc, MgZn, Molecular Dynamics Simulation, Mechanical Properties.