Effects of alloying elements on elastic properties of Ni by first-principles calculations

The effects of alloying elements (Al, Co, Cr, Cu, Fe, Hf, Mo, Nb, Pt, Re, Ta, Ti, W, Y and Zr) on the elastic constants (c_ij's) of Ni have been investigated using first-principles calculations within the generalized gradient approximation. The results are compared with the available experimental data and analyzed based on the volume changes and electron density. It is found that the shear modulus decreases with increasing volume caused by alloying addition and the bulk modulus (B) is related to the total molar volume (V_m) and electron density (n) with the relationship, n ∝ sqrt(B / V_m). The melting temperatures of Ni-X dilute solutions calculated from the available thermodynamic databases have been compared to those obtained from the empirical relationship with the elastic constant c₁₁. The calculated elastic constants show good relationships with the mechanical properties such as 0.2% flow stress and give us a guideline to understand and develop Ni-based superalloys.