B1914 Ni-Based Superalloy Properties After Solution Heat Treatment and Long-Term Exposure at High Temperature

Abstract

In this study, we investigated the microstructural evolution resulting from various solution heat treatments and the effects of thermal exposure at 900 °C for 1000 and 2000 h on the B1914 Ni-based superalloy, aiming to represent the material's conditions close to thermodynamic equilibrium. Between 1080 and 1150 °C, only partial solution of the γ′-cuboidal phase occurred, with no dissolution of the Ti-rich γ-γ′ and γ-M3B2 eutectics. At temperatures above 1200 °C, incipient melting occurred at the interdendritic region. Around 1200 °C, without incipient melting, the γ-M3B2 eutectic was completely dissolved into the γ-phase through solid-state reaction. Under thermal exposure conditions, the γ-γ′-M3B2 microstructure remained unaltered, showing good correlation with the predicted phase equilibria. Only changes in the morphological structure of the M3B2-phase were observed. Regarding the uniaxial tensile properties at high temperatures (750 and 1050 °C), it was observed that the presence of casting pores (quantified via X-ray computed tomography) had a more pronounced effect on the tensile behavior of the B1914 superalloy after 2000 h of thermal exposure compared to the resulting microstructural modifications at 900 °C.