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<p>This investigation utilizes first-principles calculations within the framework of Density Functional Theory (DFT), employing the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA), to systematically elucidate the structure–property relationships inherent to orthorhombic CuBi. The mechanical stability of the orthorhombic crystal structure was rigorously confirmed by assessing its adherence to the Born-Huang stability criteria. Subsequent analysis revealed a profound elastic anisotropy, which was quantitatively characterized through the evaluation of directional-dependent elastic moduli and established anisotropy metrics. The material’s mechanical response is indicative of ductile metallic behavior, a conclusion robustly supported by its elevated Pugh’s ratio (<i>K</i>/<i>G</i> = 2.743) and universally positive Cauchy pressures across all principal planes. To deconstruct its deformation characteristics, the Kleinman parameter (<i>ζ</i> = 0.814) was computed, indicating that bond bending mechanisms are the predominant mode of deformation over bond stretching. Furthermore, the fracture toughness (<i>K</i><sub><i>IC</i></sub>) was estimated via Niu’s empirical relation to be 1.108&#xa0;MPa·m<sup>1/2</sup>. The pronounced elastic anisotropy was further quantified, yielding a universal anisotropy index (<i>A</i><sup><i>U</i></sup>) of 1.11. This anisotropy is underscored by significant directional variance in mechanical moduli, evidenced by extreme ratios for Young’s modulus (<i>E</i><sub><i>max</i></sub>/<i>E</i><sub><i>min</i></sub> = 2.29), shear modulus (<i>G</i><sub><i>max</i></sub>/<i>G</i><sub><i>min</i></sub> = 3.27), and Poisson’s ratio (<i>v</i><sub><i>max</i></sub>/<i>v</i><sub><i>min</i></sub> = -32.19), confirming the critical dependence of mechanical properties on crystallographic orientation. Thermophysical analysis yielded a low Debye temperature (<i>Θ</i><sub><i>D</i></sub> = 181.84&#xa0;K) and a notably high thermal expansion coefficient (<i>α</i> = 65.3&#xa0;ppm/K). Concurrently, a minimal lattice thermal conductivity (<i>k</i><sub><i>ph</i></sub> = 1.364 W/mK) was calculated. Taken in aggregate, these thermophysical findings strongly suggest the presence of significant anharmonic phonon effects and substantial phonon scattering within the material.</p>

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Atomistic insights into CuBi intermetallic compound: a quantum–mechanical study of structural integrity, elasticity, and thermodynamic behavior

  • 期刊论文

  • 发表日期：

    2025年11月22日

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  • Hsien-Chie Cheng,
  • Yang-Lun Liu,
  • Ching-Feng Yu

摘要

This investigation utilizes first-principles calculations within the framework of Density Functional Theory (DFT), employing the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA), to systematically elucidate the structure–property relationships inherent to orthorhombic CuBi. The mechanical stability of the orthorhombic crystal structure was rigorously confirmed by assessing its adherence to the Born-Huang stability criteria. Subsequent analysis revealed a profound elastic anisotropy, which was quantitatively characterized through the evaluation of directional-dependent elastic moduli and established anisotropy metrics. The material’s mechanical response is indicative of ductile metallic behavior, a conclusion robustly supported by its elevated Pugh’s ratio (K/G = 2.743) and universally positive Cauchy pressures across all principal planes. To deconstruct its deformation characteristics, the Kleinman parameter (ζ = 0.814) was computed, indicating that bond bending mechanisms are the predominant mode of deformation over bond stretching. Furthermore, the fracture toughness (KIC) was estimated via Niu’s empirical relation to be 1.108 MPa·m1/2. The pronounced elastic anisotropy was further quantified, yielding a universal anisotropy index (AU) of 1.11. This anisotropy is underscored by significant directional variance in mechanical moduli, evidenced by extreme ratios for Young’s modulus (Emax/Emin = 2.29), shear modulus (Gmax/Gmin = 3.27), and Poisson’s ratio (vmax/vmin = -32.19), confirming the critical dependence of mechanical properties on crystallographic orientation. Thermophysical analysis yielded a low Debye temperature (ΘD = 181.84 K) and a notably high thermal expansion coefficient (α = 65.3 ppm/K). Concurrently, a minimal lattice thermal conductivity (kph = 1.364 W/mK) was calculated. Taken in aggregate, these thermophysical findings strongly suggest the presence of significant anharmonic phonon effects and substantial phonon scattering within the material.