Aluminium based metal matrix composites (MMCs) offer higher specific stiffness and strength, better wear resistance and greater thermal stability when compared to the corresponding unreinforced alloys [1]. One of the outstanding challenges in the use of these materials concerns their joining, since traditional fusion welding processes generally lead to microstructural defects, also due to the presence of the ceramic reinforcement and, consequently, to a general decrease in their mechanical properties [2]. These problems can be significantly reduced by the use of solid state joining techniques, such as Friction Stir Welding (FSW) [3]. A main limitation of this process, however, could be the severe wear of the pin [4]. This problem could be overcome by using Linear Friction Welding (LFW), in which the bonding of two flat-edged components is achieved through frictional heating, caused by their relative reciprocating motion, under an axial compressive force [5], without using any consumable tool.
Linear friction welded joints on a 2124Al/SiCp composite were already studied by some of the authors in terms of residual stress caused by the process [6]. The aim of this work was to evaluate the effect of linear friction welding on the microstructure and mechanical behaviour of the composite, by hardness, tensile, fatigue and impact tests.