Author(s)

V. S. K. G. Kelekanjeri, S. K. Sondhi, T. Vishwanath, F. Mastromatteo & B. Dasan

Abstract

Coarsening of γ′ precipitates in nickel-base superalloys is one of the mechanisms by which creep damage occurs in these alloys. This is brought about by a concomitant increase in the interparticle spacing, which results in faster dislocation movement and therefore, faster creep strain accumulation. Therefore, it is vital to accurately quantify the γ′ coarsening kinetics, which is essential for creep prediction via microstructure-based continuum damage mechanics models. In the present article, we report on coarsening studies of bimodally distributed γ′ precipitates in DS GTD111TM (Trademark of the General Electric Company). The baseline microstructure of GTD111TM consisted of a cuboidal secondary γ′ population and a much finer, spherical tertiary γ′ population with respective mean radii of 266 and 34nm. Long-term aging experiments were conducted on baseline samples at temperatures of T1Keywords

nickel-base superalloy, GTD111™, γ’ precipitate, γ-γ’ microstructure, bimodal distribution, coarsening, ostwald ripening, kinetics, creep, continuum damage mechanics