Effect of heat treatment and long-term age on microstructure of a Ni₃Al-based single crystal superalloy

A new Re-containing Ni₃Al-based single crystal superalloy was recently developed by our group. In order to obtain uniform microstructure and further improve mechanical properties of superalloy, the heat treatment regime (i.e. solution treatment and age treatment) was investigated by experimental analysis and dynamics calculation (by JMatPro), and the optimal heat treatment regime was 1335-1355°C/16 h, air cooling (AC)+1140°C/2 h, AC+870°C/32 h, AC. Meanwhile, completely heat-treated experimental alloy was long-term aged at 1150°C for 25-1000 h, which showed very good microstructural stability and the coarsening behaviour of γ' phases agreed well with the typical Lifshitz-Slyozov-Wagner (LSW) theory.