In the last decade, metal-graphene composites have seen significant progress and have received increasing attention because of graphene's ability to improve the mechanical properties. The main mechanism of improvement in metal graphene composite is based on the impeding of dislocations by graphene sheets. The work includes studying the mechanisms behind the improvement caused by graphene sheets and particles using Molecular Dynamics and Density Functional Theory. Interatomic potentials that play an important role in determining the accuracy of Molecular dynamics simulations are developed for Cu-C, Ni-C, Ti-C, and Ni-Ti-C systems. Nanolayered metal-graphene composites are fabricated and the effect of graphene particles on crack's path are investigated by electron microscopy. The mechanisms behind crack's behavior is investigated by atomistic simulations and by comparing energy release rates. Metallic systems that do not deform by dislocations like metallic glasses, NiTi etc. are reinforced with graphene and are also examined by atomistic simulations. In addition, a novel metal-graphene composite in which the metal matrix undergoes a uniform large recoverable phase transformation when subjected to mechanical loading is proposed and investigated using atomistic simulations. The material has the potential to overcome the long-standing challenge of transferring the extraordinary mechanical performance of nanoscale materials to the bulk level. / Doctor of Philosophy / In the last decade, metal-graphene composites have seen significant progress and have received increasing attention because of graphene's ability to improve the mechanical properties. The main mechanism of improvement in metal graphene composite is based on the impeding of dislocations by graphene sheets. The work includes studying the mechanisms behind the improvement caused by graphene sheets and particles by studying the interaction of metal and Carbon atoms in graphene. Functions that simulate these interactions play important role in determining the accuracy simulations. These functions are developed for Cu-C, Ni-C, Ti-C, and Ni-Ti-C systems. Nanolayered metal-graphene composites are fabricated and the effect of graphene particles on crack's path are investigated by electron microscopy. The mechanisms behind crack's behavior is investigated by atomistic simulations and by comparing energy release rates. Metallic systems that do not deform by dislocations like metallic glasses, NiTi etc. are reinforced with graphene and are also examined by atomistic simulations. In addition, a novel Graphene-Metal composite in which the metal matrix undergoes a uniform large recoverable phase transformation when subjected to mechanical loading is proposed and investigated using atomistic simulations. The material has the potential to overcome the long-standing challenge of transferring the extraordinary mechanical performance of nanoscale materials to the bulk level.

The objective of this dissertation is to develop amorphous metal thin films (AMTFs) for two-terminal electrical device and nanolaminate applications. Two AMTFs, ZrCuAlNi and TiAl, are investigated in both two-terminal electrical device and nanolaminate applications. Material properties including composition, atomic order, surface morphology, surface potential, and electrical resistivity are explored. Application of AMTFs as electrodes in tunneling MIM diodes leverages the ultra-smooth AMTF surface morphology which results from the amorphous atomic order of AMTFs. Analysis methodologies using tunneling MIM diode I-V characteristics are described. A methodology used to estimate potential barrier heights is applied to tunneling MIM diode with differing lower electrode material, upper electrode material and upper electrode deposition technique. A second methodology used to estimate relative tunneling MIM diode insulator thickness is also presented. The presented I-V characteristic analysis methodologies illustrate that tunneling MIM diodes fabricated with AMTF lower electrodes possess tunable I-V characteristics. Nanolaminates are layered materials fabricated with alternating dissimilar thin-film layers. The flexibility of AMTF nanolaminates is illustrated through the presentation of amorphous metal/oxide nanolaminates fabricated with differing AMTFs and aqueous solution deposited oxides. TEM and XPS depth profile analysis of realized nanolaminates are presented. The optical dielectric response of ZrCuAlNi/aluminum phosphate oxide (AlPO) and TiAl/AlPO nanolaminates are evaluated through polarized reflectance measurements and effective medium theory. The optical dielectric response of the nanolaminates differ from the optical dielectric response of the component layers. ZrCuAlNi/AlPO and TiAl/AlPO nanolaminates therefore satisfy the definition of metamaterials. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from May 9, 2012 - May 9, 2013