Molecular Dynamics Study on the Compressive Behavior of Intermetallic Compounds in 3xxx Aluminum Alloys

The morphology and distribution of intermetallic compounds (IMCs), such as Al₆Mn, Al₂Cu, and Al₁₂Fe₃Si₂, play a critical role in determining the mechanical properties of 3xxx series aluminum alloys. In this study, the compressive behavior of these IMCs was systematically investigated using the modified embedded atom method (MEAM) potential and the large-scale atomic/molecular massively parallel simulator (LAMMPS) under various temperatures and strain rates. The results show that as the temperature increases from 623 K to 823 K, both the compressive strength and elastic modulus of the IMCs decrease significantly. Al₁₂Fe₃Si₂ exhibits the lowest compressive strength, ranging from 1.1 to 9.8 GPa, while Al₂Cu demonstrates the highest compressive strength, ranging from 3.9 to 19.8 GPa. Within this temperature range, Al₆Mn and Al₃Fe show relatively poor stability. At a strain rate of 1 × 10¹⁰ s^-1, the thermal sensitivity coefficients for compressive strength are 0.010 and 0.008, and those for elastic modulus are 0.173 and 0.126, respectively. In contrast, Al₂Cu exhibits the best stability, with thermal sensitivity coefficients of 0.005 for compressive strength and 0.041 for elastic modulus. Furthermore, the influence of strain rate diminishes notably under lower temperatures. Across the entire temperature range, Al₂Cu displays the highest overall stability, with a strain rate sensitivity index ranging from 0.3527 to 0.3738.