Factors affecting the room-temperature mechanical properties of TiCr 2-base Laves phase alloys

Abstract

Various effects on the room-temperature mechanical properties of TiCr 2-base alloys have been assessed in efforts to improve the toughness of Laves phase intermetallics (AB 2). Systematic studies were performed on: (i) single-phase stoichiometric and nonstoichiometric TiCr 2, (ii) TiCr 2-base ternary Laves phases, and (iii) two-phase binary alloys containing TiCr 2. In order to make quantitative comparisons among the different alloys, Vickers indentation was used to obtain hardness and fracture toughness values. Within the single-phase field, constitutional defects accounted for the compositional dependencies of properties, and may aid the synchroshear deformation process. Ternary Laves phases comprised of Fe, Nb, V or Mo additions to TiCr 2 indicated that alloying elements which partition to both A and B sublattices can improve the toughness. Stabilization of the cubic C15 crystal structure also resulted in higher toughness values. Small amounts of the bcc β-phase effectively reduced crack lengths in the Laves phase, and two-phase alloys of (Ti,Cr)+TiCr 2 exhibited significant improvements in toughness.