Molecular Dynamics Simulations Of Tension At The Ni/Al Film Interface

Interfacial Mechanics of film is a helpful method for studing the phenomenon of fracture and damage of film materials (devices). The fracture and damage of film materials (devices) is usually take place in the interface of film and substrate. So one good mehod of illustrating the binding properties of film and substrate is espacially needed and becomes as one convern. In this thesis, three-dimensional molecular dynamics of simulations of the Ni/Al bi-metal film system is used in the axial tensile loading process. We will discuss the initial misfit dislocation configuration of the interface and the glide dislocations erupt from the interface. The initial dislocation configuration influences the glide dislocation. We also disscuss a series temperature loading of the system and contrast them. At last we compare the initial dislocation configuration of Ni/Al interface and Ni/Cu interface.The Ni/Al film system tensile loading process of simulation results show that: Ni/Al film tension process can be divided into elastic deformation and plastic deformation section. In the elastic deformation section, stress increases linearly with strain growth. In the plastic deformation section, the stress strain curve will exhibit plastic flow. After the relaxation, the initial misfit dislocation of Ni/Al film on is formed in the three different interfaces. The initial misfit dislocation network is different. In the Ni(001)/Al(001) system, the dislocation configuration is a grid-like network. In the Ni(110)/Al(001) film system, the dislocation configuration is very chaotic and disordered. And in the Ni(111)/Al(001) system the dislocation configuration is fold line network. Then tension process take place. When glide dislocations begin to emit, dislocations are emitted from misfit dislocation lines in both [110] and [110] directions at the interface of Al(001)/Ni(001) and Al(001)/Ni(111) systems. Since misfit dislocation network at the interface of Al(001)/Ni(110) is disordered, the glide dislocation planes are arbitrary from the interface. When glide dislocations are expanding from interface, dislocation planes might collide with each other and when collisions occur, some other disordered dislocation atoms would dissociate from these planes. This is the phenomenon of release of dislocation energy. Then the loading simulation is taken at the temperature of 10K, 50K, 150K, 300K. In the elastic deformation section, stress-strain ratio (elastic modulus) decreased, the yield stress also decreased. Finally, the comparation of initial dislocation configuration is taken between Ni/Al and Ni/Cu film system. The results show that, in the (001)/(001) system, the misfit dislocation lines gap is different. The gap of the dislocation lines of the Ni(001)/Al(001) system is 20?. Ni(001)/Cu(001) system is 29?.