Dependence of the temperature of phase transformations and of the structure of heat-resistant nickel alloys on the heating temperature of melts
Conclusions1.The temperature of onset of crystallization of the melt, the dispersity of the dendritic and eutectic structure, the distribution of the alloying elements in the dendritic cells of heat-resistant nickel alloys are determined by the degree of supercooling of the melt which in its turn depends on the heating temperature of the melt prior to solidification.2.Heating of the melt to more than 1720°C brings about the maximal lowering of the temperature of onset of crystallization (for alloy 4 by 60°C) relative to the liquidus, and increased dispersity of the structure. Yet the temperature of complete dissolution of the γ′-phase in the solid solution and the solidus of alloys in the solid state do not change.3.When the melt interacts with the material of a ceramic mold, the heating of the melt prior to crystallization does not influence the characteristics of the structure of the alloy.