Effects of Homogenization Treatment on the Microsegregation of a Ni–Co Based Superalloy Produced by Directional Solidification

To reduce microsegregation, a series of homogenization treatments were carried out on Ni–Co based superalloy prepared through directional solidification (DS). The element segregation characteristics and microstructural evolution investigated by optical microscopy (OM), scanning electron (SEM), probe microanalysis (EPMA). results show that the elements are non-uniformly distributed in solidified superalloy, which W Ti have greatest tendency microsegregation. Furthermore, severe microsegregation leads to complicated precipitations, including ?-Ni3Ti eutectic (? + ??). EPMA Al Mo uniformly between ??) ? matrix, whereas is segregated ? phases. positive Ti, continuously rejected into remaining liquid during matrix solidification, promotes formation transformation phase. According effect, optimal single-stage process this alloy 1180 °C for 2 h because sufficient diffusion elements. In present study, kinetic model was built reflect degree homogenization, coefficients estimated.