Effects of solution treatment parameters on microsegregation of a Ni-based single crystal superalloy

A Ni-base single-crystal superalloy containing 4wt.%Re was directionally solidified under liquid metal cooling (LMC), followed by stepwise solution treatments. Under high thermal gradient, the dendrite structures are greatly refined with increasing withdrawal rates. After the stepwise solution heat treatments, the residual segregation of alloying elements such as Ta, Re and W etc., reduces with the refined structure, which can be attributed to the reduced characteristic diffusion distance. In addition, as the increase of solution-treated temperatures, the residual segregation of refractory elements can be reduced.