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The formation of transition zones during explosive welding of aluminium with copper in vacuum and in air is studied. The distribution of element concentrations is used to determine the coefficient of mutual mass transfer in the undetachable Al--Cu joint. It turns out that the mass transfer of copper into aluminium in the conditions of explosion welding occurs at greater depths compared to the depth of penetration of aluminium into copper. This is explained by the fact that the nature of the penetrating atoms does not have such a strong influence as in conditions of diffusion annealing, and the determining factor is the lattice period, which in aluminium is larger than in copper. Concentration curves are plotted for the Al--Cu interaction zone during explosion welding, in which there are no intermetallic phases corresponding to the equilibrium diagram of state. The coefficient of mutual mass transfer turns out to be several orders of magnitude higher than the heterodiffusion coefficient of the same elements under diffusion-annealing conditions. The explosion welding is performed using a coaxial scheme by throwing a copper tube on an aluminium rod. [ABSTRACT FROM AUTHOR]

The article discusses network centrics technologies and their application to warfare which would integrate all forces sand weapons in a common information environment in combat. Topics discussed include the origins of the concept of network-centric warfare, the assessment of a hypothetical adversary capable of network-centric technologies, and trends in common information environment during warfare.

Powders of Fe, Co and Ge blended in mixtures of Fe60Ge40, Co60Ge40, Fe30Co30Ge40 (at.%) were synthesized into alloys by milling in a high energy ball-mill. Only β-phases with hexagonal structure B82 are formed in all alloys after 2 h of mechanical alloying (MA). In Fe60Ge40 and Fe30Co30Ge40 chemical interaction occurred with simultaneous formation of β-Fe5Ge3 and FeGe2. In the system of Fe-Ge the FeGe2 phase is characterized by the highest negative enthalpy of formation in comparison with other phases, therefore it is preferably formed at the initial stage of MA. In the Co60Ge40 alloy the β-Co5Ge3-phase is formed without intermediate reaction products. The obtained β-phases have a nanocrystalline structure (13–18 nm) and are characterized by considerable local chemical heterogeneity. Structural transformations during heating to 720°C of metastable β-Fe5Ge3 result in a stable B82 phase and consist of micro deformation relaxation and elimination of chemical heterogeneity. The heating of chemically heterogeneous β-Co5Ge3 results in its stratification and formation of metastable Co2Ge with orthorhombic structure. At T ≥ 630°C, Co2Ge redissolves in hexagonal β-Co5Ge3 and after heating to 720°C the β-phase becomes chemically homogeneous. [ABSTRACT FROM AUTHOR]