Determination of the Ni3(Ti, Al) dissolution boundary in a directionally solidified superalloy

The microstructure of most as-cast superalloys is highly anisotropic and inhomogeneous. In precipitation hardenable materials it is desirable to know the precipitate dissolution temperature to homogenize the microstructure and tailor the size and distribution of the precipitates to obtain the optimal material properties. Differential thermal analysis, heat treatments followed by microstructural characterization and a dilatometry technique were used to determine the dissolution temperature of the precipitate phase. The values obtained for the dissolution temperature from the three methods are all in agreement and indicate that the dissolution temperature for a nominal superalloy is approximately 1200 °C.