Estimation of densities and coefficients of thermal expansion of solid Ni-base superalloys

To calculate the densities of solid Ni-base superalloys as functions of temperature and composition, lattice parameters of 18 alloys at 20°C and coefficients of thermal expansion (CTEs) of 17 alloys were estimated by combining available data. To estimate the lattice parameters of the alloys at 20°C, the changes in the lattice parameter of Ni caused by additions of the elements were simply summed to get the lattice parameters of alloys. This procedure results in calculated densities that are < 1% in error for all 18 alloys. For the densities of the alloys at an elevated temperature, the CTEs were then estimated. The CTEs of the 17 Ni-base alloys were gathered and regressed to yield the CTE as a function of temperature and composition. The CTEs calculated from the regressions are < 10% in error for all 17 alloys at 400, 700, 1000 and 1300 K. These errors of the CTEs also result in densities that are within 0.5% error or less in the overall temperature range.