Effect of Zr on solidification and microstructure of a Ni-based superalloy with high Al and Ti contents

Abstract

Ni-based wrought superalloys are key materials for aero-engines turbine disks, chiefly owing to their superior corrosion, fatigue and creep resistance at elevated temperatures [1,2] . To satisfy the demand that aero-engines continue to develop, the total amount of γ′ (the main strengthening phase) forming elements Al and Ti in advanced alloys has reached 7.5wt.% [3,4] . However, the more the addition of (Al+Ti), the easier to form nonequilibrium eutectic (γ+γ′) and η phase at the final solidification stage [5,6] . U720Li is a relatively advanced Ni-based superalloy containing high (Al+Ti) content [7,8] . It was found that the eutectic (γ+γ′) and η phases were easy to become source of crack initiation sites during hot deformation of U720Li ingots [9] . Thus, these two phases must be eliminated by high temperature

Effect of Ta on solidification characteristics and mechanical properties of DZ411 Ni-based superalloy

“…It is of critical importance to improve the high temperature strength of directionally solidified columnar Ni-based superalloy. According to the development experience of aero-engine blades, optimizing the microstructure of alloys by adding refractory elements (Mo, W, Re, Ta) would be effective in improving the hightemperature strength of alloys for IGTs [6][7][8] .…”