Synthesis of Cu-Al2O3 Nano Composite by Thermochemical Method

Copper reinforced with extremely fine and uniform alumina dispersoids has shown remarkable thermal and mechanical stability at an elevated temperature. Particularly, its mechanical properties do not decrease with the increase in temperature, keeping good electric conductivity even up to near copper melting point. Such nanostructured composite materials therefore have attracted much attention to the applicability of high-performance electrode for industrial spot welding [1]. These materials have been widely used as lead frames and electrical connectors. Their use has also been suggested in connection with the International Thermonuclear Experimental Reactor(ITER)[2]. Conventional melting and casting techniques are not useful because they are unable to give good uniformity of dispersoids. This material therefore had to be produced by the powder metallurgy method only. The internal oxidation process, in which the alumina particles with the size of 20–100 nm have been synthesized, has offered a good technique for fine and uniform dispersion of alumina in copper matrix [3].However, One of main defects of internal oxidation method is the non-homogeneous distribution of oxide particles, which negatively influences on the mechanical and electrical characteristics of Cu-Al2O3 composite material[4]. A few trials such as mechanical alloying or rapi solidification have been tried to overcome such problems, but have often shown a contamination and poor economical efficiency[5]. Recently, Jena et al.[6] have developed a novel method for preparing nanocomposites of Cu–Al2O3 with complete homogeneity. In their studies, besides observing the homogeneity and nanoparticle size of the components, they have indicated the presence of a new phase other than Cu and Al2O3, possibly CuAlO2. They have suggested that the high strength in the Cu–Al2O3 system might be due to the formation of a strong bonding phase at the interface of Cu and Al2O3