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.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/115292 |
| Date | 01 June 2023 |
| Creators | Agrawal, Arpit Kumar |
| Contributors | Mechanical Engineering, Shahab, Shima, Ahmadian, Mehdi, Li, Ling, Murayama, Mitsuhiro |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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