Multiwave combustion in the Me1-Me2-N2 system is rationalized in terms of catalytic combustion mechanism, without formation of planar combustion front, but via numerous combustion waves with different spatial configuration and phase shift. The process of afterburning involves formation of new waves or warm-up with the torches of burning gaseous products. The latter ones form outlet craters on the surface of burned samples.

X-ray diffraction data are presented for combustion products in the Al-W-N system. New, nonequilibrium intermetallic compounds have been identified, their diffraction patterns have been indexed, and their unit-cell parameters have been determined. The phases α-and β-WAl 4 are shown to exist in three isomorphous forms, differing in unit-cell centering. The phases α′-, α″-, and α‴-WAl 4 are monoclinic, with a 0 = 5.272 Å, b 0 = 17.770 Å, c 0 = 5.218 Å, β = 100.10°; point groups C 12/ c 1, A 12/ n 1, I 12/ a 1, respectively. The phases β′-, β″-, and β‴-WAl 4 are monoclinic, with a 0 = 5.465 Å, b 0 = 12.814 Å, c 0 = 5.428 Å, β = 105.92°; point groups A 112/ m , B 112/ m , I 112/ m , respectively. The compounds WAl 2 and W 3 Al 7 , identified each in two isomorphous forms, differ in cell metrics (doubling) but possess the same point group: P 222. WAl 2 ′ : orthorhombic, a 0 = 5.793 Å, b 0 = 3.740 Å, c 0 = 6.852 Å. WAl 2 ″ : orthorhombic, a 0 = 11.586 Å, b 0 = 3.740 Å, c 0 = 6.852 Å. W 3 Al 7 ′ : orthorhombic, Pmm 2, a 0 = 6.225 Å, b 0 = 4.806 Å, c 0 = 4.437 Å. W 3 Al 7 ″ : orthorhombic, Pmm 2, a 0 = 12.500 Å, b 0 = 4.806 Å, c 0 = 8.874 Å. The new phase WAl 3 : triclinic, P 1, a 0 = 8.642 Å, b 0 = 10.872 Å, c 0 = 5.478 Å, α = 104.02°, β = 64.90°, γ = 107.15°.

Upon variation in the duration of mechanical activation, characteristic temperatures of thermal explosion (TE) in Ti-Ni powder mixtures and phase composition of products were explored by electron microscopy, optical metallography, and XRD. The results shed new light on the mechanism of structure formation during TE and on the relationship between process parameters and product composition.

X-ray diffraction data are presented for combustion products in the Al-W-N system. New, nonequilibrium intermetallic compounds have been identified, their diffraction patterns have been indexed, and their unit-cell parameters have been determined. The phases α-and β-WAl4 are shown to exist in three isomorphous forms, differing in unit-cell centering. The phases α′-, α″-, and α‴-WAl4 are monoclinic, with a0 = 5.272 Å, b0 = 17.770 Å, c0 = 5.218 Å, β = 100.10°; point groups C12/c1, A12/n1, I12/a1, respectively. The phases β′-, β″-, and β‴-WAl4 are monoclinic, with a0 = 5.465 Å, b0 = 12.814 Å, c0 = 5.428 Å, β = 105.92°; point groups A112/m, B112/m, I112/m, respectively. The compounds WAl2 and W3Al7, identified each in two isomorphous forms, differ in cell metrics (doubling) but possess the same point group: P222. WAl2′: orthorhombic, a0 = 5.793 Å, b0 = 3.740 Å, c0 = 6.852 Å. WAl2″: orthorhombic, a0 = 11.586 Å, b0 = 3.740 Å, c0 = 6.852 Å. W3Al7′: orthorhombic, Pmm2, a0 = 6.225 Å, b0 = 4.806 Å, c0 = 4.437 Å. W3Al7″: orthorhombic, Pmm2, a0 = 12.500 Å, b0 = 4.806 Å, c0 = 8.874 Å. The new phase WAl3: triclinic, P1, a0 = 8.642 Å, b0 = 10.872 Å, c0 = 5.478 Å, α = 104.02°, β = 64.90°, γ = 107.15°.

Results of an investigation of the microstructure and phase composition of materials of the Ti-B-Fe system, obtained by self-propagating high-temperature synthesis (SHS) are presented.

Ti2B5, TiB12, TiB≃25, TiB≃55, and TiB≃100 were prepared by self-propagating high-temperature synthesis and characterized by microstructural analysis, x-ray diffraction, and x-ray microanalysis. Data on the crystal structure, lattice parameters, and mechanical properties of the synthesized borides are presented.

The mechanism of phase changes in the Ti-B-Fe system in a combustion wave for a mixture of Ti, B, and Fe powders and a ferroboron alloy-titanium mixture with the same proportion of elements is studied. It is found that the mechanism of structure formation depends significantly on the type of contact between the initial components. An x-ray phase and x-ray spectrum and structural microanalyses of the quenched layers of specimens show that the first contact melts occurring in the combustion wave are ferroboron (the first type of mixture) or ferrotitanium (the second type) melts. In the first case, the calculated high-melting compound TiB2 forms as a result of the interaction between the two melts; in the second case, it forms as a result of the interaction of the melt with solid ferroboron, which, in turn, determines the different type of microstructure of the final combustion products. The highly disperse and more homogeneous structure of the products forms after combustion of the second-type mixture. A method of producing the Ti-B-Fe pore-free composite produced during the self-propagating high-temperature synthesis (SHS-composite) by combining the combustion with rolling of the synthesis products is considered. In properties, theresulting material is similar to tungsten-carbide materials.

The combustion of Ti, B, and Fe powders is used as an example in an investigation to discover and show the role played by contact eutectics in the combustion wave. When the Ti-2B mixture is diluted by iron the combustion limit appears at a composition Ti-2b-70% Fe, and the maximum combustion temperature of 1350 C is substantially below the melting temperature of the initial materials, corresponding to the melting temperature of the TiB/sub 2/-Fe eutectic. Therefore, the formation of contact eutectics in the front significantly intensifies the reaction, and sometimes because of this it becomes possible to propagate a combustion wave. The investigation shows that conducting the combustion process in the presence of some eutectics provides a means of purposefully controlling the structure of the combustion zone and the characteristics of its propagation.

Morphological properties and some physical characteristics of TiB/sub 2/, TiB, Ti/sub 3/B/sub 4/, Ti/sub 2/B/sub 5/, and TiB/sub 12/ of the Ti-B system have been determined. The analysis of the microstructure has shown that TiB, Ti/sub 3/B/sub 4/, and Ti/sub 2/B/sub 5/ are formed by peritectic reactions and are compounds with inconsistent melting characteristics.

Phase transitions can accelerate heterogeneous reactions in solids. The combustion rate of the ϭ-FeV alloy was found to be 1.5–2 times higher than the combustion rate of α-Fe at all pressures under study. Phase transition significantly influences the formation of the final product structure. The maximum combustion temperature of the alloy was higher than the transition temperature.