Phase stability and mechanical properties of Ni3(Al1-xVx) ternary alloys: First principles study

This study investigates Ni₃(Al_1-xV_x) (0 ≤ x ≤ 1)alloys with L1₂ and D0₂₂ via first-principles calculations. Results show Al/V atoms undergo amplitude modulation decomposition in Ni₃(Al,V), minimizing lattice distortion and enabling phase transitions. For 0 ≤ x ≤ 0.625, L1₂ exhibits lower formation and mixing enthalpies than D0₂₂, with the lowest mixing enthalpy (0.58 kJ/mol) at x = 0.5, confirming superior thermal stability. L1₂'s Fermi level displays a pseudo-bandgap with minimal density of states (DOS) at x = 0.5, while its high-frequency phonon DOS distribution enhances stability. Mechanically, L1₂-Ni₃(Al_0.5V_0.5) achieves optimal hardness (12.32 GPa) and fracture toughness (21.96 MPa m^1/2), outperforming other compositions. These findings consistent with experimental mechanical properties and phase diagrams in literatures, revealing atomic/electronic mechanisms behind stability and performance.