Abstract:The indentation toughness of Mo₅Si₃-based phases was studied with regard to different alloying elements, amount of alloying addition as well as the presence of secondary phases. Cr, Ti, Nb, Ni and Co were added as alloying elements. The results show that the indentation fracture toughness of Mo₅Si₃ increases with the alloying additions, from 2.4MPa·m^1/2 for monolithic to just over 3MPa·m^1/2 for highly alloyed Mo₅Si₃. Small volume fractions of brittle secondary phases may have a positive impact on the indentation toughness; while larger fractions seems to lower the toughness.

Key words: indentation toughness; Mo₅Si₃; alloying