Gamma prime stability and its influence on tensile behavior of a wrought superalloy with different Fe contents

Abstract

Gamma prime (c9) stability and its influence on tensile behavior of a newly developed wrought superalloy with various Fe contents was studied both experimentally and thermodynamically. The results show that the c9-solvus temperature is higher and c-c9 lattice mismatch is bigger in the alloy with the lower Fe content. During long-term thermal exposure at 650-750°C, the coarsening behavior of c9 precipitates follows Ostwald ripening kinetics and the lower Fe content can decrease the coarsening rate of c9 precipitates due to the increase of the activation energy for c9 coarsening. Moreover, the lower Fe content can retard the transformation from c9 to g phase. The tensile properties of the alloys with different Fe contents are almost same after standard heat treatment. However, after thermal exposure, the decrease of tensile strength in the alloy with lower Fe content is less than that of the alloys with higher Fe content due to the improvement of c9 stability.