Predicting an alloying strategy for improving fracture toughness of C15 NbCr2 Laves phase: A first-principles study

• The lattice parameters of C15 NbCr2-based ternary compounds were calculated.
• The relationship between lattice parameters and the radii is discussed.
• The atomic free volumes of C15 NbCr2 ternary compounds have been calculated and compared.
• An alloying strategy for improving fracture toughness of C15 NbCr2 had been proposed.

Alloying is an effective method to improve mechanical properties of some compounds. The present work predicted an alloying strategy for improving fracture toughness of C15 NbCr2 Laves phase. The lattice parameters of C15 NbCr2-based ternary compounds with transition metal elements were calculated using first principles, revealing a relationship between lattice parameters and radii of transition metal elements. The atomic free volumes of a series of C15 NbCr2-based ternary compounds with transition elements were calculated and proposed as an indicator for a knowledge-based strategy for toughening enhancement of the C15 NbCr2 Laves phase. According to the presently calculated results, Re has the largest potential to improve fracture toughness of C15 NbCr2 Laves phase, since it has the largest atomic free volume, followed by Os, Ir, Tc, Ru, Rh, Cu, Pt and Mo.

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