Molecular dynamics simulations on nanocomposites formed by intel-metallic dispersoids of L12 type and aluminum matrices

초록

Molecular dynamics simulations were performed to characterize the lattice morphology in the region adjacent to the interfaces in nanocomposite systems of a Ni<inf>3</inf>Al dispersoid embedded in Al matrix (Ni<inf>3</inf>Al/Al) and an Al<inf>3</inf>Nb dispersoid embedded in aluminum matrix (Al<inf>3</inf>Nb/Al). A nearly perfect coherent interface is obtained in the Al<inf>3</inf>Nb/Al system with the lattice planes of dispersoid and matrix aligned parallel in all directions. The simulation results show the presence of the matrix atom-depleted regions near the dispersoid boundary for most cases. Detailed analysis revealed that certain sites immediately next to the dispersoid are energetically favored for the matrix atoms to occupy. The matrix atoms occupying these sites attract other atoms producing the depleted regions. In certain specific situations of Al<inf>3</inf>Nb/Al system, however, the wetting of a rotated dispersoid is overwhelmingly complete prompting the need of further study for better understanding. The order parameters of dispersoids calculated for Ni<inf>3</inf>Al in aluminum is nearly constant while that for Al<inf>3</inf>Nb in aluminum is rapidly decreasing function of temperature in the range of 300 to 1800 K.