MoSiBTi by powder metallurgy

Abstract

The molybdenum silicon boron, MoSiB, material system is considered as a promising candidate to be able to increase exhaust temperature and thereby efficiency in aero and industrial gas turbines. In the MoSiB system, the Berczik triangle has been established to describe a three-phase field to form tough and strong high temperature materials. However, adding titanium may lead to a different phase field favoring the formation of the Mo5Si3 phase over Mo3Si phase promising better creep resistance and oxidation resistance. Additionally, Ti5Si3 precipitates may increase the ductility of the alloy by reducing the silicon content in the molybdenum solid solution and at the grain boundaries. Synthesizing the material by powder metallurgy offers both new prospects and challenges towards phase formation. A thermodynamic equilibrium state, like for example a chemical homogeneous melt is never reached. In contrast local diffusion couples and the resulting phase transformations define the microstructure of the alloy.