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Dependence of the combustion of a Ti + C granular charge on a granule size is experimentally studied. It is revealed that the burning rate of a granular mixture of all fractions used in the work is higher than the burning rate of a bulk-density powder mixture. It is shown that, with a decrease in the granule size, the burning rate of the charge in the absence of gas decreases due to an increase in the number of boundaries between the granules per unit length of the sample. A strong influence of the nitrogen flow on the burning rate of both coarse and fine granules is established. It is shown that, in contrast to fine granules, an increase in the nitrogen flow rate of coarse granules up to 600 liters/h leads to a transition to convective combustion. The studies performed indicate that, despite the structural analogy between mechanically activated and granular mixtures, the relationship between the combustion time and the front transition time in granular mixtures is completely different. This means that the combustion of granular mixtures even in the absence of a gas flow cannot be explained within the framework of a microheterogeneous model. [ABSTRACT FROM AUTHOR]

Gasless combustion of a mechanically activated Ni-Al mixture is experimentally studied; the process is compared with the characteristics of combustion of a nonactivated Ni-Al mixture. Mechanical activation of the Ni-Al mixture is shown to form layered conglomerates consisting of numerous layers of the initial components. As a result, the structure of the medium becomes very similar to a cellular structure, which forms the basis for advanced microheterogeneous models of gasless combustion. A relation between the local (microscopic) and global (macroscopic) parameters of gasless combustion is found. Modification of the microstructure of the initial medium by means of mechanical activation allows obtaining products whose microstructure differs significantly from the microstructure of products obtained from nonactivated mixtures. [ABSTRACT FROM AUTHOR]