Friction stir forming to fabricate copper-tungsten composite

Tungsten embedded composite of copper (C1100) was fabricated through probeless tool aided friction stir forming (FSF). The heat input conditions and forging were determined to be most effectively controlled by the tool rotation speed. A void-free and continuously bonded Cu-W interface was established at the parameter combination of 1200 rpm tool rotation speed with 100 mm min−1 traverse speed, 0.05 mm plunge and 3° tool tilt angle. The Cu-W interface was characterized via SEM and EDS analysis and was determined to be a purely mechanical interlock due to the absence of new phases. Microstructure of the friction stir formed copper near the interface was examined by optical microscopy. Mechanical properties of the processed copper were investigated by Vickers indentation and shear punch tests, and they showed good correlation with the microstructure. Grain refinement induced work hardening was observed in the copper close to the interface. Cu-W interface remained intact during the shear punch testing and failure occurred in the grain coarsened region of the copper 1 mm away from the interface. The bond strength of the Cu-W mechanical interlock fabricated by FSF was determined to be 130 MPa.