Microstructure and stress-rupture property of an experimental single crystal Ni-base superalloy with different heat treatments

The influence of heat treatment on the microstructure and stress-rupture property at 1,100 °C/140 MPa was investigated in a 5.0 wt% Re containing experimental single crystal Ni-base superalloy. The results indicate that the γ′ morphology is nearly cuboidal in the dendrite core after conventional heat treatment. The lattice misfit of alloy becomes more negative after modified heat treatment and results in more cuboidal γ′ precipitates than that after conventional heat treatment. The increased stress-rupture life after modified heat treatment is attributed to higher γ′ volume fraction, more negative lattice misfit, well-rafted structure, and narrower γ channel width.