Development of a new magnetic aluminum matrix nanocomposite

This article presents the results of a comparative investigation on microstructure, mechanical properties and magnetic characteristics of aluminum matrix nanocomposites reinforced with nickel ferrite nanoparticles. Magnetic nickel ferrite (NiFe2O4) nanoparticles with average size of 35 nm were synthesized via citrate-nitrate route and were used as the reinforcement phase in commercially pure aluminum matrix. Aluminum matrix samples with 0, 1, 2.5, 5 and 10 wt% ceramic reinforcement were fabricated using the powder metallurgy process. The sintered samples were then extruded at 400 °C to improve the density and homogeneity of the composite. Optical microscopy, SEM, FESEM, densitometry, XRD, DSC and VSM analyses were all used to evaluate the microstructure, porosity distribution, density, existing phases, possible reactions between the matrix and the reinforcements and magnetic properties of the samples. The results showed that the relative density of the composites decreased as the reinforcement weight percent was increased. The samples yield stress and ultimate tensile strength increased by increasing the weight percent of the reinforcement up to 5 wt%, however, they dropped at 10 wt% reinforcement content. The compressive yield stress, magnetization and coercivity of the composites were all observed to increase as the reinforcement content increased. However, the elongation of composite samples decreased considerably as the reinforcement content increased.