Influence of MechAnIcAl AnD therMAl treAtMents on MIcrostructurAl trAnsforMAtIons In cAst IronsAnD propertIes of synthesIZeD DIAMonD crystAls purpose. To analyze how the structural transformations in the cast iron metal matrix near graphite inclusions influence the features of synthesis of metastable diamond crystal on diamond polycrystals (substrate) synthesized by shockwaves.Methodology. In experiments, we used the laserinduced detonation of explosive charges to create a flat shockwave front and employed chemical, microstructural, spectral and Xray phase analyzes. In particular, the features of chemical element distribu tion in cast iron phases, dislocation density in a solid solution, crystal lattice parameters, and others were studied.findings. It has been shown that solidphase autoepitaxy is a physically justified, experimentally proved and stably reproduc ible phenomenon. The accelerated transfer of carbon atoms to the surfaces of metastable diamond growing crystals in the kinetic mode is facilitated by a number of factors that cannot be quantified by numerically evaluated parameters. These include, first of all, the microstructure of the growing medium (cast iron matrix), carbon source, temperature and deformation fields that ensure transformation of polymorphic graphite to diamond with emerging gradient stress fields at the stages of forging, exposure to shock waves and thermal cycling. Defect redistribution in the crystal structure of the metal matrix and graphite inclusions plays a certain role at the mesoscale. It has been found that saturation with microstructural defects brings higher physicochemical activity to the system in the whole. originality. For the first time in world practice, diamond single crystals have been synthesized that contain the inclusions of polycrystalline diamond particles of shockwave origin inside the single crystal shell; this may indicate a general discreteness of natural diamond formation.practical value. The growth of single metastable crystal on polycrystalline diamond of shock wave synthesis is the most favor able in case of using austenitic gray cast iron with foliate graphite inclusions. The experimentally proved diamond growth in a solid medium under pressure and temperature within the range of graphite stability can be used to develop new lowenergy tech nologies for the synthesis of metastable diamond single crystals.
The results of experimental research of processes of ignition and combustion of particles of aluminum and magnesium alloys in gaseous purges of high-temperature decomposition of solid pyrotechnic fuels leading to their fire explosive hazardous development are presented. The relevance of these research is due to the wide scope of application of pyrotechnic products based on pyrotechnic mixtures of powders of aluminum-magnesium alloys with additives of organic substances, in particular applications in military technology and use in various industries related to the rotation of solid pyrotechnic equipment. Accordingly, in case of fire at facilities where pyrotechnic products are kept or during their transportation there exists the risk of ignition of pyrotechnic mixtures with different acceleration of their subsequent combustion process and destruction of the pyrotechnic products. As a result, high-temperature combustion products are formed, which are fire hazardous to the surrounding environment. Based on the foregoing, it is necessary to obtain data on the regularities of ignition and combustion particles of aluminum-magnesium alloys, which determines the ability to predict the properties of fire hazard pyrotechnic mixtures. As a result of conducted research, data on the ignition and combustion of particles of aluminum-magnesium alloys was obtained, in particular, the dependence of the delay time of the particles of aluminum-magnesium alloys on their chemical composition was obtained, the data on the process of combustion of particles of aluminum-magnesium alloys was obtained, the data on the effect of additives to aluminum-magnesium alloys was obtained.
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