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.