FUNDAMENTALS OF INCREASING THE HEAT RESISTANCE OF CAST NICKEL-BASED COMPLEX-ALLOY ALLOYS
The analysis of doping of the chemical and phase composition of domestic and foreign cast heat-resistant alloys with nickel matrix, where there is a tendency to increase the level of heat-resistant properties of foundry nickel alloys due to more complex doping. Recently, more and more expensive rheniums, rutheniums, gaffniums, and dysprosium have become used as doping elements. The positive effect of these elements on the thermostability of the y matrix and strengthening y' phases has been established. The above elements inhibit diffusion processes, thereby increasing the resistance of alloy creep at high temperatures and loads. Assessment of heat-resistant nickel alloys obtained by the method of directed crystallization is given. It has been established that the most revealing parameters of the phase composition of the alloys studied are the distribution ratios of doping elements between y' and y phases (Ki). The basic principles of balanced doping are formulated, on which the optimal chemical composition of heat-resistant nickel alloys (HNA) is chosen. It is shown that misfit (y/y') is mainly determined by those doping elements that most greatly increase the a<sub>y</sub>. These elements in order of increasing the effect on the period of the lattice (a<sub>у</sub>) phases are Re, Pu, Mo, W, Nb and Ta.