Factors Affecting the Room-Temperature Mechanical Properties of TiCr₂-Base Laves Phase Alloys

Katherine C. Chen, California Polytechnic State University - San Luis Obispo
Samuel M. Allen, Massachusetts Institute of Technology
James D. Livingston, Massachusetts Institute of Technology

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DOI: http://dx.doi.org/10.1016/S0921-5093(97)00526-1.

Abstract

Various effects on the room-temperature mechanical properties of TiCr₂-base alloys have been assessed in efforts to improve the toughness of Laves phase intermetallics (AB₂). Systematic studies were performed on: (i) single-phase stoichiometric and nonstoichiometric TiCr₂, (ii) TiCr₂-base ternary Laves phases, and (iii) two-phase binary alloys containing TiCr₂. 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 TiCr₂ 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)+TiCr₂ exhibited significant improvements in toughness.