Interface microstructure observation for welds of an alumina ceramics and an aluminum alloy with friction stir spot welding

Abstract

A 5 mm thick alumina ceramic plate and a 1 mm thick aluminum alloy plate were welded together by a friction stir spot welding technique. The welding was performed at tool rotation rate of 2000 rpm, plunge time of 0.4 mm, dwell time of 60 s, and plunge rate of approximately 0.1 mm/min. The interface microstructure of the welds was investigated by a scanning transmission electron microscope and energy dispersive X-ray spectrometry analysis to study the welding mechanism. A magnesium element was detected along the interface. It was expected that the alumina ceramic plate and the aluminum alloy plate were welded via magnesium oxide or a magnesiumaluminumoxygen compound.