Experimental investigation of structure, composition and properties of novel metal-carbon covetic materials

covetic materials;nanoindentation;tensile strength;energy absorption;crystallite size

Nilufar, Sabrina

关键词: covetic materials;    nanoindentation;    tensile strength;    energy absorption;    crystallite size;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/50353/Sabrina_Nilufar.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Covetics are novel metal-carbon materials invented by Third Millennium Materials (TM2), LLC (Waverly, Ohio). In these materials metals such as copper, aluminum, zinc, silver, gold or other base metals or their alloys are combined with high weight percent of carbon powder (up to 9 wt %) in a new way. In this dissertation an experimental investigation was carried out to study mechanical properties, structure and composition (carbon content) of copper and aluminum alloy-based covetics. Covetic materials of 7075 Al, 6061 Al and 10200 Cu alloys obtained from TM2 were tested. 7075 Al materials were warm rolled while the other two materials were as-cast and no heat treatment was done on any of the samples. The 7075 Al covetic materials had carbon contents of 0, 3 and 5 wt%, 10200 Cu covetic materials had carbon contents of 0, 3, 5 and 9 wt% and 6061 Al covetic materials had carbon contents of 0 and 2.3 wt% as reported by TM2. The mechanical properties of covetics were measured by tensile test (Young’s modulus, 0.2% yield strength, ultimate tensile strength, and elongation), Charpy impact test (energy absorption), nanoindentation (elastic modulus and hardness) and Vickers and Rockwell methods (hardness). Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) were used to analyze the structure of these materials. Carbon content of covetic materials was examined by Energy Dispersive Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS). The experimental results indicate significant changes in the mechanical properties and structure of covetics with increasing carbon content. For Al covetics, mechanical testing showed the following enhancements in properties over the corresponding base materials: higher 0.2% yield strength and ultimate tensile strength, higher hardness (Rockwell, Vickers and nanoindentation), higher energy absorption (impact energy) and lower density, as carbon content increased.XRD showed an increase in the lattice constant and a decrease in the average crystallite size with carbon increase. However, for the Cu covetics there was an optimum wt% of carbon beyond which the properties did not improve. In summary, the covetics studied in this dissertation exhibited improved mechanical properties with an increase in the carbon content which make them promising candidates for many engineering applications.