Role of melt state and carbon content in the crystallization process of heat resistant nickel-based alloy, containing 0.002, 0.006, 0.015, 0.07 and 0.14 mass% C is studied. An influence of maximum heating temperature and carbon concentration on temperature of crystallization beginning, formation of the carbide and eutectic phases as well as decomposition of the solid solution with formation of secondary γ'-phase is considered.