Processing, Characterization and Optimization of Mechanical Properties of a Al/NbB2 Composite

Despite the low density of ceramics, an appealing characteristic for aerospace applications, diboride compounds cannot be used in critical applications due to their brittle nature. The purpose of this research was to study physical properties of niobium diboride specimens containing different levels of aluminum. In the fabrication of the new composite, different homogenization techniques were used, including jar milling and high energy ball milling. Powder samples are shaped into green bodies using a cylindrical chamber pressed to 7500 psi. The samples were sintered at 600^oC for two hours in a vacuum capsule to avoid oxidation. It was found that boride particles size reduction by fragmentation is the key to highly homogeneous samples and that ball milling is an effective method to homogenize the dispersed phase distribution in the composite. Also, percentages of aluminum ranging from 25 to 40 wt % were found to be more effective in the sintering process.