Investigation On The Deformation And Breaking Mechanism Of Nanoscale Metallic Materials

Electronic plating plays an important role in the national economy. In this paper, with models of nanowires and nanocrystalline, computer simulations are used to study the deformation and breaking failure mechanism of nanoscale metallic materials under effects of crystallographic orientation, defect distribution, temperature and strain rates induced by mechanical shocks. The deformation behaviors are investigated to know how to control the breaking of the nanowires using defects.1. Shock-induced breaking of the copper nanowire with the dependence of crystallographic orientation and strain rate.In this part, the breaking failure is studied for the equilibrium, quasi-equilibrium, and non-equilibrium deformation of the [100], [110] and [111] single-crystal copper nanowires stretching at strain rates from 0.01% to 7.69% ps-1. The statistical breaking position distributions of the nanowires have been given an effect of strain rate and crystallographic orientation on micro-atomic fluctuation in the symmetric stretching of the nanowires. When the strain rate is less than 0.26% ps-1, macro-breaking position distributions exhibit the anisotropy of micro-atomic fluctuation. However, when the strain rate is larger than 3.54% ps-1, the anisotropy is not obvious because of strong symmetric shocks. 2. Shocks-induced breaking in the gold nanowire with the influence of defects, temperatures and strain rates.In this part, molecular dynamics simulations are used to study the deformation and breaking failure of the [100] single-crystal gold nanowires containing defects at different strain rates. The statistical breaking position distributions of the nanowires show mechanical shocks play a critical role in the deformation of nanowires at different strain rates, and deformation mechanism of the nanowire containing defects is based on a competition between shocks and defects in the deformation process of the nanowire. At low strain rate of 1.0%ps-1, defect ratio of 2% has changed the deformation mechanism because micro-atomic fluctuation is in an equilibrium state. However, owing to strong symmetric shocks, the sensitivity of defects is not obvious before defect ratio of 25% at high strain rate of 5.0%ps-1.For the influence of the temperature on the deformation and breaking failure of the [100] single-crystal gold nanowires containing defects, the statistical breaking position distributions show the deformation and breaking of the nanowires have a dependence on the applied temperature, and the sensitivity of the nanowire to defects is based on a competition between constructed defects and disorder crystalline structures induced by temperatures. At low temperature of 100 K, defect ratio of 25% has decided the breaking of the nanowire because micro-atomic fluctuation is in an equilibrium state. However, owing to acute atomic movements, the sensitivity of defects to breaking is not obvious before defect ratio of 70% at high temperature of 500 K.3. The grain boundary interface effects of the nanocrystalline copper on its deformation and breaking behaviors under uniaxial stretching.Using molecular dynamics simulations, we have investigated systematically grain boundary interface effects on the deformation and breaking behaviors of the [110]‖[100], [111]‖[100], and [111]‖[110] nanocrystalline interfaces. For [110]‖[100], breaking occurred easily at the interface with no clear structural deformation of the grain interior. When the [111] direction is addressed, the sliding most likely takes place in [100] region for [111]‖[100]. [111]‖[110] behaves interface amalgamation in the uniaxial tensile deformation, and it breaks in the [110] region. These cause obvious elongation of the [111]‖[100] and [111]‖[110] nanowire, not for the [110]‖[100]. It is attributed to the grain boundary interface effects of the nanocrystalline interfaces.4. The temperature effects of the nanocrystalline copper on its deformation behaviorsThe failure of the nanoscale metallic interface has raised concerns owing to the effect of interface amalgamation on its application to nanoelectronic devices. The single crystal copper [110] and [100], which are set as two components of the [110]‖[100] nanocrystalline copper, are used to simulate the interfacial property using molecular dynamics simulation. Repeated tension and compression cycles show that the two components of the interface can contact and separate without interfacial amalgamation. The [110]‖[100] interface could withstand momentary shocks of compression and heat produced by the momentary shocks. This property of [110]‖[100] interface is dominated by crystalline orientations of interfacial structure, in comparison with [111]‖[100] and [111]‖[110] interfaces under the same conditions.