Surface modification by filtered cathodic vacuum arc and nanomechanical properties of thin-film media, copper aluminum nickel shape-memory alloy, and surface-textured silicon

The objective of this dissertation was twofold: (1) investigation of the effects of different surface modifications on the surface microstructure, nanomechanical properties and friction characteristics of silicon and a cobalt-based alloy, and (2) analysis of the pseudoelastic behavior of a shape-memory alloy due to cyclic nanoindentation loading.;Filtered cathodic vacuum arc (FCVA) is a novel film deposition method in which the film precursors are energetic ions, as opposed to neutral atoms or clusters of atoms in traditional deposition techniques like sputtering and chemical vapor deposition. FCVA exhibits two important advantages, i.e., the flow direction and energy of the film precursors can be independently controlled by magnetic and electrical fields, respectively, and the absence of a working gas enables film deposition over a wide temperature range. However, there are also important challenges in FCVA treatments, such as arcing spot instabilities and plasma fluctuations.;A customer-made direct-current FCVA system is presented in this dissertation that uses a special magnetic-field mechanism to stabilize the plasma. The effectiveness of this FCVA system to produce high-quality films is examined in the context of results of the microstructure and nanomechanical properties of amorphous carbon films synthesized under different FCVA deposition conditions. The ion implantation mechanism and surface treatment of the FCVA system were investigated both theoretically and experimentally. Single-crystal silicon and a cobalt-based alloy (magnetic recording media) were modified by FCVA treatments. Silicon has many applications in the semiconductor industry and micro-electro-mechanical systems (MEMS), while cobalt-based alloy is the magnetic recording medium of hard disks. The present FCVA system was used to form an ultrathin overcoat on silicon and an overcoat-free magnetic medium with its surface modified by the FCVA technique to enhance the surface corrosion and were resistance. Particular attention was given to the surface chemistry, morphology, and nanomechanical properties of the FCVA-treated surfaces.;A second main objective of this dissertation was the investigation of the microstructure and nanomechanical properties of a Cu-Al-Ni shape-memory alloy, know as the shape-memory alloy with the largest reversible strain (∼17%). Transmission electron microscopy (TEM) and Rutherford backscattering spectroscopy (RBS) studies were carried out to study the microstructure of this alloy. The pseudoelastic behavior of Cu-Al-Ni at the nanoscale was demonstrated by cyclic nanoindentation experiments. This behavior is associated with the stabilization of the martensite phase with the increase of the indentation cycles.;Nanoscale surface topography modification of silicon by ion beam bombardment was also investigated in this dissertation. Nanoindentation and nanoscratching tests performed with diamond tips of radius close to the size of the surface features (ripples) produced by ion-beam texturing revealed scale-dependent nanomechanical properties and anisotropic friction behavior.