The Effect of the Nickel Content and Mechanical Activation on Combustion in the 5Ti + 3Si + xNi System

Intermetallic alloys are synthesized in the 5Ti + 3Si + xNi system by the method of self-propagating high-temperature synthesis (SHS) and mechanosynthesis. The influence of the nickel content on the morphology, size, and yield of composite particles after the mechanical activation (MA) of the mixtures is studied. The dependencies of the maximum temperatures and combustion rates, phase composition, morphology, and elongation of synthesis products on the nickel content for the initial and MA mixtures are studied. Under the conditions of the experiments conducted in this study, the combustion process is realized and at the same time the samples burn completely at a nickel content of 10 to 60 wt % in the 5Ti + 3Si + xNi system. After the MA, the samples from the 5Ti + 3Si mixture burn completely, and during the activation of the 5Ti + 3Si + 40% Ni mixture, mechanochemical synthesis takes place. With the increasing nickel content, the combustion temperature decreases, and the combustion rate behaves nonmonotonically, the size of composite particles increases and the yield of the mixture after MA decreases. MA practically does not affect the maximum combustion temperatures of mixtures of 5Ti + 3Si + xNi. A multiple (from 0.7 to 2.9 cm/s) increase in the burning rate of samples from MA mixtures with an increase in the Ni content from 20 to 30 wt % is recorded. An increase in the nickel content leads to an increase in the content of triple phases and the amount of melt in the synthesis products of mixtures of 5Ti + 3Si + xNi.