Production of aluminum/alumina composite by new methods Roohollah JAMAATI*, Mohammad Reza TOROGHINEJAD* * Isfahan University of Technology, Materials Eng. Dep., Isfahan-Iran r.jamaatikenari@ma.iut.ac.ir toroghi@cc.iut.ac.ir Abstract A technique, called CAR (continual annealing and roll-bonding) process, was used to produce an aluminum matrix composite dispersed with different quantity of alumina particles. Adding the alumina to matrix was carried out by two interesting methods. In first method (CAR-1), the alumina particles and in second method (CAR-2), the anodizing process for formation of alumina was used. The results were revealed that increasing the number of cycles improves the distribution of alumina particles in the aluminum matrix. The microstructure of the fabricated composites at end of the CAR process showed an excellent distribution of alumina particles in the aluminum matrix for both methods and no porosities were observed between the aluminum layers and also between aluminum matrix and alumina particles. The composites produced by CAR-1 and CAR-2 processes exhibited a higher tensile strength than the monolithic and the annealed aluminum strips while the changes in elongation values were not pronounced. The results also indicated that the tensile strength of the composites increased as the number of CAR cycles increased. Keywords: Metal matrix composites, CAR process, Anodizing process, Mechanical properties, Microstructure 1. INTRODUCTION Particle and short fiber reinforced metal matrix composites (MMCs) have unique and desirable thermal and mechanical properties such as high strength and high elastic modulus. They are also relatively inexpensive, compared to their continuous fiber reinforced counterparts, and can be processed by conventional techniques. Also, discontinuously reinforced MMCs containing particulates are of particular interest to the industrial community owing to their isotropic behavior. Aluminum is a light and relatively weak metal. Its applications are limited when a high modulus and enhanced strengths are required. Although high-strength aluminum alloys have been developed, the addition of alloying elements and microstructural control has a very small effect in enhancing their stiffness. The demands for lightweight, high-modulus, and high-strength materials have led to the development of MMCs [1-3]. Many manufacturing processes have been used for producing such composites. In general, most metal matrix composites are produced by squeeze or stir casting, spray forming, or powder metallurgy techniques. In these methods, reinforcements are incorporated or added into the matrix by ex situ methods. Homogenous reinforcement and strong bonding of reinforcements with the matrix will certainly improve mechanical properties; however, the reinforcement particulates used in these methods tend to agglomerate, leading to a non- homogenous distribution and poor wettability of reinforcement oxides, thus decreasing the mechanical and electrical properties of the composites obtained. Another problem of this casting method is the sinking or floating behavior of reinforcement in the melt, depending on particle-to-liquid density [4]. A number of efforts, such as mechanical alloying, have been