Phase field and room-temperature mechanical properties of C15 Laves phase in Nb-Hf-Cr and Nb-Ta-Cr alloy systems

摘要

The pseudo-binary NbCr_2-HfCr_2 Laves phase alloys exhibited a large off-stoichiometric range while the pseudo-binary NbCr_2-TaCr_2 Laves phase exhibited a limited off-stoichiometric range. The fracture toughness of the ternary Nb-Hf-Cr and Nb-Ta-Cr Laves phase alloys was higher than those of the binary NbCr_2, HfCr_2 and TaCr_2 Laves phase alloys, and decreased in the (Nb,Hf)-rich region of the C15 Laves phase. Depending on the alloying species and associated defect structures, room-temperature toughness of the C15 phase can be beneficially or deleteriously affected.