Molecular dynamics simulation on elastic behavior of Ni/Ni3Al interface with graded structure

The basic concept of the functionally graded material (FGM) is an active co ntrol of the structure of materials to be suitable for the object propertie s. This concept should be expanded to the atomistic level. In the present r eport, this idea is applied to the Ni(gamma)/Ni3Al(gamma') (100) interface. Molecular dynamics simulation is performed to clarify the correlation betw een the atomistic structure of the interface and the microscopic elastic pr operties. The Ni-Al binary 64000 atom systems with the FGM and NFGM type in terface structures are simulated at 298 K with Finnis-Sinclair potential. T he spatial local distribution of the lattice constant, the site potential e nergies and the atomistic stress energies are analyzed under the strain fre e condition. The global and local changes of these properties are calculate d for various elastic tensile conditions. The lattice constant misfit and t he stress concentration at the interface is weakened by the application of the graded structure to the gamma/gamma' interface. Under the elastic tensi le condition, the stress gap at the interface is proportional to the tensil e strain for the standard (NFGM) interface. On the other hand, in the FGM s tructural interface, such an increase of the stress gap is not observed. Th e atom level graded structure is certified to be effective to reduce the st ress at the interfaces under elastic deformation conditions.