The influence of sintering temperature on the characteristics of the Cu-xAl۲O۳ composites

The exquisite characteristics of Cu-Al۲O۳ composites such as low thermal expansion and high thermal conductivity have offered these composites as favorable materials for applications like spot welding electrodes and packaging materials for the integrated circuits. To fabricate the Cu-Al۲O۳ composites with favorable properties, the copper powder was blended with up to ۲۰ weight % of γ- alumina particles, then mechanically alloyed using a high energy ball mill route. The resultant powder mixtures were cold-pressed then sintered at various temperatures of ۸۵۰, ۹۰۰, and ۹۵۰ °C to evaluate the effect of sintering temperature on the density and fracture energy of the synthesizedcomposites. The grain structure and the formed phases were characterized using scanning electron microscopy equipped with an energy dispersive spectroscopy, and X-ray diffractometry. Besides, the impact Charpy standard test and the Archimedes method were used to measure the fracture toughness and density of the composites, respectively. According to the results, the fracture toughness of the synthesized composites decreases with increment in their alumina content. So the Cu–۵%Al۲O۳ composite with an impact energy of ۴.۱ joules showed the highest fracture toughness. The higher misfit strains at Cu/Al۲O۳ interface, as well as the higher surface energy of the mechanically alloyed powders through enhancing the formation of interfacial CuAl۲O۴ and CuAlO۲ compounds thus reduction the particles clustering, lead to an intensive reduction in densification, but a rather acceptable fracture toughness for Cu-۲۰%Al۲O۳ composite after sintering at ۹۵۰˚C.

کلیدواژه ها:

Cu-Al۲O۳ composites ، misfit strain ، particle clustering ، fracture toughness ، sintering.