Work

Design, computational and experimental investigation of NbTa0.5Ti-X (X = Al, Zr, V, Mo, Hf) multiple-principal-element alloys with synergistic strength and fracture strain

Year: 2026

Type: article

Abstract: The effects of refractory metals Mo, V, Zr, Hf, and non-refractory metal Al on the phase formation, solid solution behavior, and mechanical properties of NbTa 0.5 Ti-based refractory multiple-principal-element alloys (RMPEAs) were studied using CALPHAD, empirical parameter analysis, and first-principles DFT, combined with vacuum arc melting experiments. The addition of Al, Mo, Hf, V, and Zr effectively enhances the strength of NbTa 0.5 Ti alloy. Mo significantly improves strength and deformation resistance but reduces toughness, while V improves toughness; Al, Hf, and Zr reduce toughness. NbTa 0.5 Ti-X (X = Mo, V, Zr, Hf, Al 0.6 ) RMPEAs were prepared and characterized in as-cast and annealed states. All alloys show dendritic microstructures with elemental segregation. After annealing at 1000 °C for 24 h, NbTa 0.5 TiAl 0.6 exhibits a prominent yield strength increase from 1103 MPa to 1518 MPa due to intragranular Al-rich precipitates, at the cost of compressive ductility. Experimental results agree well with computations. Strong correlations are confirmed between DFT-calculated elastic constants and experimental strength/hardness; Pugh ratio and Cauchy pressure reliably predict toughness trends. Atomic size mismatch ( δ ) quantitatively indicates solid-solution strengthening. This work establishes a CALPHAD + empirical parameters + DFT framework to screen effective alloying elements for strengthening NbTa 0.5 Ti while maintaining room-temperature compressive ductility, providing a reproducible strategy for composition–property design of high-performance RMPEAs.

Source: Results in Engineering

DOI: 10.1016/j.rineng.2026.112103