Microstructure Evolution of a Single Crystal Nickel-Base Superalloy During Heat Treatment and Creep

摘要

Microstructure evolution of a single crystal nickel-base superalloy during heat treatment and tensile creep at 1010°C and 248 MPa for 30h was observed and analyzed. Internal stresses because of lattice mismatch between and / phase provided the driving force for / shape evolution during heat treatment. More than 65 vol. % distorted cubic phase keeping coherency with the y matrix precipitated after solution at 1295°C for 32h. The shape of phase was perfectly cubic with increasing precipitate size during the two-step aging treatment. Due to the applied stress and internal stress field the continuous y1/ lamellar structure perpendicular to the applied stress was formed after 30h tensile creep.