| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 105 === In this study, molecular dynamics (MD) are used to simulate the nanoimprinting behaviors of Ag thin films with impurities using a cuboid diamond punch. Additionally, nanoimprinting behaviors of a bi-crystal silver film was also discussed. Wherein the single punch nanoimprinting acted to specimen, in which two impurities was set at the both side of the punch, separately. For double punches nanoimprinting, the silver film contained an impurity located between the punches in order to explore the effect of impurity on the deformation mechanism.
The specimen with bi-crystal silver thin film were constructed by (001)_(110) and (001)_(111) crystal. The imprinting position is located at the grain boundary of the silver thin film, so the effect of grain boundary on the geometrical characteristics of the formed hole could be investigated.
In addition, the effect of the pitch of the punches was changed to study the influence of nanoimprinting. The effect of the impurity defect on nanoimprinting behaviors with double punches was also investigated.
The simulation results show that the thin film structure of the FCC, the appearance of the forming hole is depended on the crystal orientation. In the indentation process, the sliding of the dislocation will be impeded by the impurity, resulting in dislocations piled up, thus affecting the shape of the formed hole.
In the process of nanoimprinting of bi-crystal silver thin film, the grain boundary will also affect the slippage of the dislocation. As the punch continued to press, the grain boundary will migrated due to the different of surface energies of the various crystal planes. As the results, the grain boundary effect for the plastic deformation mechanisms and the shape of the formed hole are obviously. In the process of double-punch nanoimprinting, impurity particles affect the formed hole that result in a cave located at the silver surface between the punches.
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