MOLECULAR DYNAMICS SIMULATION OF THE SIZE EFFECT ON THE ELASTIC PROPERTIES OF THE B2-NiAl NANOFILM

In the paper, molecular dynamics simulation with the modified analytical embedded atom method (MAEAM) is applied to study the size effect on the elastic properties of the B2-NiAl nanofilm. The simulation results indicate that there is a critical thickness, which is about 5.38 nm, to distinguish the size dependence of the elastic properties of the nanofilm. On the one hand, these properties, such as the averaged cohesive energy and the bulk modulus, change evidently as the size is smaller than the critical thickness and the change tendency is tightly controlled by the surface atom composition. On the other hand, as the nanofilm size exceeds the critical one, the calculated values of the elastic properties are almost independent of the film thickness. Relatively, the bulk modulus magnitude of the nanofilm is apparently larger than that of the corresponding bulk material. Finally, the inherent mechanisms of the size impacting on the elastic properties of the B2-NiAl nanofilm have been discussed in more detail. The strengthening effect of the bulk modulus results from the smaller multilayer relaxation of the interlayer distance as compared to those of the bulk materials.