Impact of Phase Distribution on the Fracture Toughness of High Temperature Resistant Mo-Si-B Alloys

Abstract

Abstract Due to their high melting point and good creep resistance, Mo-Si-B alloys have the potential to be used as structural materials at extremely high temperatures in the future. Apart from the relatively ductile Mo solid solution, three-phase molybdenum-based alloys including the intermetallic phases Mo3Si und Mo5SiB2, which enable low fracture toughness, especially at room temperature. A promising approach for fracture toughness improvement consists in the production of a microstructure in which the intermetallic phases are embedded in the ductile Mo solid solution matrix. This paper looks at different powder- and ingot-metallurgical production processes and the resulting microstructures. Particular attention will be paid to the impact of structural component size and phase distribution on the fracture toughness at room temperature.