a study on the effect of al2o3 nano-particles on aging behavior and mechanical properties of al-4.5wt.%cu/al2o3 composites produced by stir casting

using the nanotechnology and decreasing the dimension of reinforcement particles to nanometer, outstanding mechanical properties are achieved in aluminum matrix nanocomposites. fabrication of aluminum matrix nanocomposites by casting is of great importance because of its simplicity, low cost and ease of the control of matrix microstructure. in this study, the aging behavior of nanocomposite samples with different volume percents nano-particles, i.e. 1.5, 3 and 5%, have been investigated. for production of composite samples with al2o3 nano-particles using the al-4.5%wt.cu alloy as its matrix, mixtures of al powders (with the particle size of about 35 m) and suitable amounts of alumina powders (about 50 nm in size) were prepared by mechanical alloying process to be used in casting process. microstructural studies showed a uniform distribution of reinforcements in al-4.5wt.%cu matrix in the samples with a considerable grain refining effect on the matrix. the effects of reinforcement particles on compressive properties, hardness, and density of composite samples as well as the kinetics of heat treatment were also investigated. addition of al2o3 particles as the reinforcement component to the matrix changed the aging behavior of the samples. the results showed that the addition of nano-sized alumina particles to the matrix accelerates the aging process of the matrix and results in higher peak hardness values.