Journal of Materials, Processes and Environment
Volume 2, Numéro 1, Pages 1-7

Liquid-solid Phase Equilibria Of The (ni-cr-co-w) - Al -ta, Multiconstituent System. Type Superalloys.

Authors : Boutarfaia Slimane . Taouinet M. .

Abstract

Liquid-solid and solid-state phase equilibra have been studied in the S-Ni Al-Ni3Ta triangle of the S-Al-Ta system where S is solution solid of (Ni-Cr-Co-W), in the S-rich corner, using a combination of several experimental techniques. Five primary phase occur in this region, including the ternary compound, π, S6TaAl, which enters into equilibrium with each of the other four. Another compound S8Ta, forms in the solid state by decomposition of the Ta-rich Ni solid-solutions and occurs in equilibrium with the γ, π and δ (S3Ta) phase. The extent of these different phase fields has been determined at 1250°C and particular attention has been paid to the γ- γ’ solvus surface which has been shown to be accurately described by a second-order polynomial function of the atomic concentration.

Keywords

Superalloys, turbine blades, ternary phase diagram, phase equilibria