Joining parts by diffusion welding is one of the recent manufacturing techniques, since it allows manufacturing of similar or dissimilar parts, and complex components with high precision. It is difficult to weld Aluminium and its composites by conventional fusion welding techniques. Thus, In this study, diffusion welding technique was applied to weld Al+5-10-15% WCp composites in argon gas. An experimental set up has been designed and series of experiments have been performed, Metallographical examinations have been carried out to determine the welding quality. It was concluded that changes in volume fraction of the reinforcement particles strongly affect the weldability of the materials and their microstructures.