Fabrication of functionally gradient Ni-based superalloy by casting

Fabrication of the functionally gradient material (FCM) directly by casting was proposed and applied to the Ni-based superalloy. A gradient of materia l properties was manifested by a monotonical increase of the average grain size accompanied by the decrease of the Vickers hardness starting from the edge to the centre of the model ingot. These two parameters (grain size, ha rdness) were much profitable in comparison with the conventional cast ingot s. Variation of the morphology of precipitates within the gradient zone was revealed in the transmission electron microscopy study. Factors involved i n the formation of the FGM were discussed and the appropriate hypotheses we re presented.