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<p>Iridium(Ir)-based superalloys with γ/γ' two-phase microstructure are recognized as next-generation high-temperature materials for aerospace engines operating above 1500&#xa0;°C. The strengthening phases can markedly enhance the mechanical strength of alloys. However, these phases exhibit significant brittleness, and their properties in Ir-based alloys remain insufficiently investigated. Here, the high-throughput calculations were employed to screen the potential γ' phases for Ir<sub>3</sub>X (X = Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Pt, Au, Th) through systematic assessment of phase stability, melting points, shear modulus and anti-phase boundary (APB) energies. Subsequently, lattice misfit was further optimized through third-element compositional design in Ir<sub>3</sub>(Ti<sub>0.5</sub>X<sub>0.5</sub>) (X = Nb, Hf, Zr, Ta). The dependence of yield strength on precipitate size was systematically evaluated through the precipitation strengthening effect. Ir<sub>3</sub>(Ti<sub>0.5</sub>Ta<sub>0.5</sub>) displays a reduced lattice misfit (0.63%), accompanied by a higher shear modulus (207&#xa0;GPa), elevated APB energy (920&#xa0;mJ&#xa0;m<sup>−2</sup>), and an increased Poisson’s ratio (0.25), demonstrating a synergistic improvement in these interrelated mechanical characteristics. The increase of density of states value at Fermi level and the right-shift of the peak in the bonding region result in the improved ductility. The greatest delocalization degree of electrons around Ta and the shorter Ir-Ta bond lengths are responsible for its higher shear modulus and APB energies. A novel Ir<sub>3</sub>(Ti<sub>0.5</sub>Ta<sub>0.5</sub>) composition balancing the trade-off between high strength and ductility is expected to guide the development of Ir-based superalloys.</p> Graphical abstract <p></p>

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Tailoring precipitation-strengthening in Ir-based ternary alloys: a first-principles approach to L12 phase engineering

  • 期刊论文

  • 发表日期：

    2025年8月25日

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  • Xian-Pei Jiang,
  • Wei Yu,
  • Yan Wei,
  • Hai-Jun Wu,
  • Ji-Ping Ding,
  • Chang-Yi Hu,
  • Xing-Jun Liu,
  • Jing Feng,
  • Xiao-Yu Chong

摘要

Iridium(Ir)-based superalloys with γ/γ' two-phase microstructure are recognized as next-generation high-temperature materials for aerospace engines operating above 1500 °C. The strengthening phases can markedly enhance the mechanical strength of alloys. However, these phases exhibit significant brittleness, and their properties in Ir-based alloys remain insufficiently investigated. Here, the high-throughput calculations were employed to screen the potential γ' phases for Ir3X (X = Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Pt, Au, Th) through systematic assessment of phase stability, melting points, shear modulus and anti-phase boundary (APB) energies. Subsequently, lattice misfit was further optimized through third-element compositional design in Ir3(Ti0.5X0.5) (X = Nb, Hf, Zr, Ta). The dependence of yield strength on precipitate size was systematically evaluated through the precipitation strengthening effect. Ir3(Ti0.5Ta0.5) displays a reduced lattice misfit (0.63%), accompanied by a higher shear modulus (207 GPa), elevated APB energy (920 mJ m−2), and an increased Poisson’s ratio (0.25), demonstrating a synergistic improvement in these interrelated mechanical characteristics. The increase of density of states value at Fermi level and the right-shift of the peak in the bonding region result in the improved ductility. The greatest delocalization degree of electrons around Ta and the shorter Ir-Ta bond lengths are responsible for its higher shear modulus and APB energies. A novel Ir3(Ti0.5Ta0.5) composition balancing the trade-off between high strength and ductility is expected to guide the development of Ir-based superalloys.

Graphical abstract