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This paper presents the results of an investigation of the fine crystal structure of Dalan diamonds synthesized from graphite and carbon black by detonation. The phase composition of the diamond powders was found to vary widely; the structural and structural-morphological states of diamond particles were studied. The main types and subtypes of detonation diamonds are characterized according to transmission electron microscopy data. Assumptions are made concerning diamond formation during detonation synthesis. INTRODUCTIONAt present, the production of diamond powders by using detonation synthesis (DS) is of scientific and practical significance. The first is determined by the importance of knowing the physical nature of the formation of nanodispersed diamond particles, and the second is related to the solution of the problem of producing submicron-sized and nanosized diamond powders of uniform particle size. Such powders can be used both as the starting product and to produce nanodispersed ultrahard compact and composite materials.It is known that the detonation synthesis of diamond is based on the two main technological approaches which differ in the nature of the starting nondiamond carbon. The first approach uses the starting carbon in the form of graphite or carbon black [1][2][3][4][5] in a mixture with a high explosive (HE), and the second uses the socalled own carbon formed by the decomposition of a HE. In the second case, mixtures of TNT and RDX are more often used [6][7][8][9]. There is also a third approach to the detonation synthesis of diamond, in which, along with HE, graphite or carbon black, special carbon-containing additives are introduced into the charge to increase the detonation parameters of the charge. In this case, not only graphite or carbon black but also the carbon of the additives is transformed to diamond [10,11]. According to [11], using the third approach, an amorphous diamond-like form of carbon was produced in a significant amount. The diamonds synthesized in [1-5 and 10, 11] using the first approach are referred to by the abbreviations DAG and DAS, and those produced by the third approaches are referred to as DAP; the abbreviations contain information on the nature of the starting carbon and the diamond produced.The diamond synthesized using the second approach (from the carbon of HE molecules) is referred to as ultrafine diamond in the literature. Data on the processes and structural mechanisms of synthesis of this diamond and its properties and regions of application are generalized and discussed in detail in books [12][13][14] and overviews [15][16][17].The detonation synthesis of diamond from graphite and carbon black have been less studied than that of ultrafine diamond, but, nevertheless, the main data on the nature of this process and structural conversions of the starting nondiamond carbon to diamond have been obtained. In particular, the detonation parameters necessary for the synthesis of diamond and the dependence of these parameters on the type of HE, the concentration ...

in the amount of 2 and 5 wt.%, respectively). It is established that the maximal strength (445 MPa) is characteristic of the material B 13 C 2 over the whole temperature range. It does not change up to 1600°C. The increase in strength of B 4 C-based samples is revealed over the range of 1200 to 1600°C, mainly for high-porous materials (10-12%). Presumably, this is due to the higher relaxation properties of porous material microstructure.Developing high-density materials based on compounds with covalent bonds and studying their structureformation, strength, and degradation mechanisms in different loading conditions are the most important tasks of ceramic materials science. Of great interest among engineering ceramics are monophase materials and composites based on boron carbides (B 4 C, B 13 C 2 ) that may be used to fabricate light armor, in nuclear reactors, and under strong abrasion at