A Fundamental Investigation of the Laser Engineered Net Shaping Process for the Fabrication of Nanostructured Cermets

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The research objective of this grant is to investigate the suitability of the Laser Engineered Net Shaping system for the direct net-shape fabrication of nanostructured tungsten-carbide-cobalt cermets and to develop a fundamental understanding of the thermal aspects of the process. This will be accomplished by making nanostructured tungsten-carbide-cobalt cermets in both simple and complex shapes. Physical and mechanical properties of these samples, such as microhardness, yield strength, tensile strength, and modulus of elasticity, will be evaluated. In-situ temperature characterization of the area of the sample affected by the laser beam will be conducted using a two-wavelength imaging pyrometer system, which provides information on the thermal history and the resulting thermal stresses during deposition. X-ray diffraction, in combination with optical microscopy, scanning electron microscopy, transmission electron microscopy and image analysis, will be used to characterize the size distribution, volume fraction and phase decomposition of nanosized tungsten carbide particles in the cobalt matrix, and to establish the relationship between processing variables and particle size, shape and distribution. Different deposition parameters will be used in order to assess the thermal stability of the nanosized tungsten carbide particles and its interaction with the cobalt matrix. Finally, the economic and environmental benefits will be quantitatively assessed, with the use of technical cost modeling and life cycle assessment techniques. If successful, the benefits of this work will include the ability to fabricate complex shapes with better mechanical properties for products such as tools, dies and nozzles. By using the Laser Engineered Net Shaping system, the need for machining will be minimized, resulting in reduced manufacturing costs, minimized material waste through scrap generation, improved material properties, increased process efficiency, reduced product design time, and reduced environmental contamination. The results of this work will also further the scientific understanding of nanostructured materials and net-shape forming techniques. Furthermore, collaborative activities with industry and national laboratories will be strengthened, and educational programs, including those for underrepresented minorities, will be enhanced.