The role of lattice constant in strength-ductility synergy of TiVNbMoCr high-entropy alloys

BL Wu and ZD Xu and NF Zou and GS Duan and YD Liu and C Esling, MATERIALS CHARACTERIZATION, 230, 115769 (2025).

DOI: 10.1016/j.matchar.2025.115769

In this study, four TiVNbMoCr high-entropy alloys were designed and prepared, of which lattice constant orderly reducing, whereas atomic radius mismatch delta, shear modulus G and valence electron concentration (VEC) maintaining the same. The role of lattice constant in strength and ductility was addressed based on experiments and molecular dynamics (MD) modelling. It was found that yield strength and ductility synchronously increased with reducing lattice constant. In plastic deformation, activated dislocation was characterized dominantly with screw type, which can easily crossly slip and form cross-kinks. With the reduction of lattice constant in the alloys, more cross-kinks formed. In terms of kink-strengthening mechanism, the enhancement of strength was attributed to the formation of more cross-kinks with a shorter characteristic length. The increase of ductility benefitted from the improvement of dislocation nucleation and cross-kink-related dislocation proliferation. The alloy with the lattice constant of 3.107 & Aring; exhibited a promising strength-ductility synergy with the tensile yield strength of 1361 MPa and the elongation of 16.9 %, superior to that of most BCC-structured HEAs.

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