Production of mosib alloys by spark plasma sintering method

This study investigates the fabrication of MoSiB alloys, which consist of a three phase mixture: molybdenum solid solution (Moss) and the intermetallic phases Mo3Si (A15), Mo5SiB2 (T2), and Mo5Si3 (T1). The goal is to produce both undoped and SiC whisker-doped compositions using spark plasma sintering (SPS). This process examines the formation of intermetallics and the distribution of whisker-based additives within the microstructure. Powdered samples were mixed using a ball mill and an ultrasonic bath, then sintered at 1600°C under a coaxial pressure of 40 MPa for 30 minutes. This temperature corresponds to the isothermal temperature in the MoSiB phase diagram. Although intermetallic phases formed, the samples did not achieve the theoretical density. The Vickers hardness values ranged from 13.84 to 18.10 GPa, and the fracture toughness values ranged from 1 to 3 MPa·m1/2. The inclusion of SiC whiskers increased the hardness but also resulted in higher porosity. Oxidation and microstructural stability tests were conducted at 1300°C in air, with four cycles of 6 hours each followed by approximately 2 hours of cooling. The results showed that the stability of these samples was comparable to the best values reported in existing literature.