Journal of Materials Processing Technology 178 (2006) 211–217 Investigation on diffusion bonding characteristics of aluminum metal matrix composites (Al/SiCp) with pure aluminum for different heat treatments M. Murato ˘ glu ∗ , O. Yilmaz, M. Aksoy University of Fırat, Faculty of Engineering, Department of Metallurgical Engineering, Elazı˘ g 23119, Turkey Received 2 December 2002; received in revised form 15 March 2006; accepted 15 March 2006 Abstract Joining characteristic of SiC particulate reinforced aluminum metal matrix composites (MMCs) with pure aluminum were investigated by diffusion bonding process. The joining quality of the Al/SiCp MMCs was studied to determine the influences of SiCp particulates with homoge- nization and age hardening on bonding properties. The experimental results indicate that the application of aging before and after diffusion bonding decreases SiC particulate accumulation, and increases other elemental concentration at interface. Especially, the application of aging treatment before the diffusion bonding of Al/SiCp MMCs to pure Al, increased Cu% concentration at interface which treats as the insert alloy. © 2006 Elsevier B.V. All rights reserved. Keywords: Diffusion bonding; Metal matrix composites; Heat treatments 1. Introduction The metallic matrix composites materials (MMCs) are becoming more popular as structural materials in industries and so forth, in particular dispersed for the discontinuously rein- forced metallic matrix composites [1]. Recently, MMCs have received substantial attention because of their improve strength, high elastic modulus and increased wear resistance over conven- tional base alloys [2]. The researches relating joining science and technology for the discontinuously reinforced metallic matrix composites becomes important at engineering application in near future [3]. The usage of the MMCs has a great potential advantages, however they have not reached widespread industrial applica- tion. The limited use of the MMCs is basically due to joining, because, fabrication of virtually any complex structure requires joints to be made. Extensive studies have been done to investigate the appropriate processes to join the similar or dissimilar com- posites [3–5]. We can classify the works on welding of MMCs into two categories: fusion welding, and solid-state welding. The joining of the MMCs has still some problems [3–6]. During welding of conventional welding methods, some problems arise. ∗ Corresponding author. E-mail address: oyilmaz@firat.edu.tr (O. Yilmaz). Especially this is the difficulty of mixing of composite matrix material with the filler material due to great viscosity and poor flowability of the liquid welding pool. This result brings out unsatisfactory welded joints [1]. In other words, due to rejec- tions of SiC particulates or whiskers by the solidification front, the normal solidification processes of the welding pool were broken down, and this leads to microsegragation or inhomoge- neous distribution of reinforcements. At the end, there would be many micro and macro defects in the weld, and the properties of welded joints will be very low [1]. Investigations have shown that it is possible to join SiCp- reinforced aluminum metal matrix composites (A/SiC MMC) by diffusion bonding methods [5–8], friction welding processes [9,10]. In regard to the diffusion bonding of discontinuously reinforced aluminum MMCs, on the surface of composite spec- imen alumina barrier, which would make diffusion bonding process more difficult exists [1]. For this problem, transition liquid phase diffusion bonding is used by using a metal foil insert between the surfaces to be joined [11]. The diffusion bonding of this kind of composites could be realized with satis- factory joining quality. Nevertheless, it is necessary to carry on further fundamental investigation on the joining characteristics of discontinuously reinforced aluminum alloy matrix compos- ites by diffusion bonding process, particularly for detection of the activation energy for dissimilar particulate reinforced alu- minum MMCs with different heat treatments. The bond specific 0924-0136/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2006.03.168