Al–Pd interatomic potential and its application to nanoscale multilayer thin films

The strong negative heat of mixing between Al and Pd atoms is unique among the experimentally studied multilayer thin films. The role of the interface on the mechanical properties and deformation mechanism of the Al–Pd binary system is studied using the first-principles calculations and molecular dynamics (MD) simulations. Firstly, the first-principles calculations are carried out to thoroughly study the ten Al–Pd compounds including Al21Pd8, Al3Pd2, Al3Pd5, AlPd2, Al2Pd5, Al2Pd, AlPd5 and three Al1Pd1 intermetallic compounds. Secondly, the obtained results are employed to construct the Al–Pd long-range empirical potential model. Finally, the MD simulations of Pd/Al (1 1 1) and (1 1 0) interface in bi-layer models under shear and Pd/Al/Pd/Al four-layer models under nano-indentation reveal several important features including: (1) Shear failure occurs at the Pd/Al interface through interface sliding and the residual interface is covered with two to three Al atom layers. (2) The critical shear stress of (1 1 1)〈−1 0 1〉 slip system is about half of those of (1 1 0)〈0 0 1〉 and (1 1 0)〈−1 1 0〉 slip systems. (3) As compared with the pure Pd/Al (1 1 1) interface, the Pd/Al (1 1 1) interface containing Al–Pd intermetallic layer is more effective as dislocation barrier, which can prevent the propagation of dislocations and enhance the shear resistance of the (1 1 1)〈−1 0 1〉 slip system.