Effect of yttrium addition on structural, mechanical and thermodynamic properties of tungsten-yttrium alloys

Based on the supercell structures of bcc-W, the effect of yttrium on the structural, mechanical, and thermodynamic properties of tungsten-yttrium alloys is investigated using first-principles calculations. In this study, five new models of tungsten-yttrium alloys are constructed, namely W₁₅Y₁, W₁₄Y₂, W₁₂Y₄, W₁₀Y₆, and W₈Y₈. The obtained values of elastic constants and mechanical criteria show that these alloys are mechanically stable. The mechanical parameters, including elastic moduli (bulk modulus, shear modulus, and Young’s modulus), Poisson’s ratio, B/G ratio, Cauchy pressure, and Vickers hardness, indicate a decrease of the mechanical properties compared to pure tungsten, though significant improvements in plasticity and ductility are observed. According to the phonon spectrum, the calculated thermodynamic parameters, such as heat capacity, entropy, and enthalpy of the alloys increase with increasing yttrium content and temperature compared to those of pure tungsten. Despite a decrease in Debye temperature, thermal conductivity and melting point with rising yttrium content, the thermal expansion coefficient shows an increasing trend. These findings provide valuable insights into the potential of tungsten-yttrium alloys for advanced applications, particularly in the context of fusion materials.