Abstract

The pressureless sintering behavior of Al_2O_3/Cu powder mixtures, prepared from Al_2O_3/CuO and Al_2O_3/Cu-nitrate, has been investigated. Microstructural observation revealed that Al_2O_3 powders with nano-sized Cu particles could be synthesized by hydrogen reduction method. The specimens, pressureless-sintered at 1400°C for 4 min using infrared heating furnace with the heating rate of 200°C/min, showed the relative density of above 90%. Maximum hardness of 16.1 GPa was obtained in Al_2O_3/MgO/Cu nanocomposites. The nanocomposites exhibited the enhanced fracture toughness of 4.3-5.7 MPacdotm1/2, compared with monolithic Al_2O_3. The mechanical properties were discussed in terms of microstructural characteristics.

• Keywords: Al_2O_3 based composites;Dispersion of Cu;Pressureless sintering;Properties;