Formation of composite CuWNi layers on ceramic substrates under shot impact treatment

The metallization of alumina samples was performed using ultrasonically assisted shot impact equipment. The alumina plate was pre-coated with a mixture of Cu-Ni-W powders and was then shot treated. The treatment resulted in the formation of a composite Cu-Ni-W layer that was cold welded to the alumina plate. The coating exhibited a nanolaminated composite structure consisting of various combinations of elemental lamellae in the stack. A nanolaminated morphology formed during the micro-forging process of the powder materials under localized compressive forces induced via shot collisions. During this process, the adjoining metallic components were flattened and shaped together. Cold welding between the metallic components occurred when different components co-deformed and moved in parallel layers. Cold welding of the metallic components was assisted by mechanically induced interdiffusion. Amorphous interdiffusion zones were observed at the Cu/W interface. The formation of transition layers and local amorphization of the alumina plate were detected at the metal/alumina interface. The alumina substrate was locally fractured under shot impact. When the metallic materials flowed, the ceramics fragments were transported over the surface along with plasticized metallic components. The alumina particles were spaced along the interlamellar regions.