Kulinich M. Thermophysical processes during brazing of the AMg6 alloy involving reactive multilayer foils.

In the work, by the example of AMg6 alloy plates, the fundamental possibility of brazing joining of aluminium alloys via local heating of the joint zone by the heat generated in the reactive multilayer foils (MF) upon the initiation in them of the reaction of self-propagating high-temperature synthesis (SHS) is shown. The conditions for the joining of an aluminium-alloy patch-plate to a larger surface for the repair of tightness of aluminium shell-type structures is studied and a scheme of such a process is proposed. To justify the suggested scheme, the thermal fields in the studied system have been calculated under non-stationary conditions of its heating by a heat source that is in thermal contact with the patch-plate. At that, the plate thickness, the characteristics of the joining materials, characteristics of the solder, and the presence of a thermal resistance in the contact zones between the system elements have been taken into account. This has allowed us to determine the parameters of the heater necessary to ensure the brazing process, depending on the thickness of the plates being joined and the adiabatic temperature of the SHS reaction in the MF. It is revealed that, to prevent melting of the patch-plate contacting the heater, the temperature of the heater during the brazing process should not exceed a certain limit value determined by the thermal conductivity of the used alloy. A method is proposed for a self-consistent calculation of the heat exchange coefficients between the elements of the system during its heating under non-stationary conditions by comparing the experimental and theoretically calculated thermograms.