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Constitutive Modeling And Experiments For The Micro And Nano Behaviors In Metals, Cheng Zhang
Constitutive Modeling And Experiments For The Micro And Nano Behaviors In Metals, Cheng Zhang
LSU Doctoral Dissertations
This work addresses the micro- and nano-behaviors in metals through constitutive modeling and experiments. The size effect encountered during nanoindentation experiments, which is known as indentation size effect (ISE), is investigated for metal materials. The ISE is believed to be related with the strain gradient at small indentation depths. Geometrically necessary dislocations (GNDs) are formed in order to accommodate the strain gradient, which results in the increase in the material hardness. The grain boundaries in polycrystalline materials play an important role on the material hardness during nanoindentation experiments as there is a soften-hardening segment in the curve of hardness as …
Deposition And Characterization Of Ceramic Thin Films And A New Experimental Approach To Evaluate The Mechanical Integrity Of Film/Substrate Interfacial Layers, Yang Mu
LSU Doctoral Dissertations
Due to their corrosion resistance, high temperature stability, high strength, and high hardness, refractory ceramic thin films and coatings have been utilized for surface engineering of mechanical components and mechanical fabrication tools. Adhesion between ceramic thin films and coatings and the substrate is of critical concern for performance and life time of coated systems. In this dissertation, a custom designed and constructed ultra-high-vacuum (UHV) vapor phase deposition system was used for the preparation of ceramic thin films through low-pressure high-density plasma assisted physical vapor deposition (PVD) methods. Deposited thin films were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), …