The paper considers the neutron-producing tantalum-tungsten-tantalum target using a niobium interlayer manufacturing variant by means of vacuum hot roll bonding for the research nuclear facility «Source of Neutrons». The metallography results and the Ta-W-Ta solid-phase junction specimens mechanical testing ones obtained by hot roll bonding in vacuum, both immediately after production and after the heat treatment in the temperature range of 900…1300°C after roll bonding, are presented. The influence of thermal annealing on the interaction nature of the clad layers with each other and with the core tungsten material of the Ta-W-Ta solid-phase junctions with Nb interlayers obtained by vacuum hot roll bonding has been studied.