ESTIMATION OF DENSITIES AND COEFFICIENTS OF THERMAL-EXPANSION OF SOLID NI-BASE SUPERALLOYS

To calculate the densities of solid Ni-base superalloys as functions o f temperature and composition, lattice parameters of 18 alloys at 20 d egrees C and coefficients of thermal expansion (CTEs) of 17 alloys wer e estimated by combining available data. To estimate the lattice param eters of the alloys at 20 degrees C, the changes in the lattice parame ter of Ni caused by additions of the elements were simply summed to ge t the lattice parameters of alloys. This procedure results in calculat ed densities that are < 1% in error for all 18 alloys. For the densiti es of the alloys at an elevated temperature, the CTEs were then estima ted. 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 c alculated 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 de nsities that are within 0.5% error or less in the overall temperature range. (C) 1998 Elsevier Science S.A. All rights reserved.