Directional solidification and phase equilibria in the Ni-Al system

A method for the optimization of a phase diagram on the basis of results fr om directional solidification experiments is proposed. The experimental mic rostructure selection map is compared with a calculated map and the input p arameters are varied until a satisfactory agreement is obtained. The calcul ation of the microstructure selection map is based on the maximum temperatu re criterion and on analytical models for the growth of plane front, dendri tic, and eutectic structures. This method is applied to the Ni-Al system wh ere the phase equilibria close to the melting point of the gamma'-Ni3Al pha se have been subject to discussion for over 50 years. A new version of this part of the phase diagram is proposed, which is coherent with the results from directional solidification experiments.