effect of some processing parameters on microstructure and hardness profiles of al-al2cu functionally graded composites prepared in-situ via interaction between molten al and solid cu

Functionally graded materials (fgms) are receiving excessive consideration as they provide optimum thermal and mechanical properties without a distinct interface between two materials. these materials are considered for many applications such as aerospace, nuclear, energy, biology, electromagnetism, optics, energy and other fields. in the present study, for the first time, al-al2cu fgms produced by employing a casting method by utilizing the interaction between molten al and solid cu. different weights of solid copper placed in a ceramic mold, pre-heated to the desired temperature and subsequently filled with molten al at various temperatures. consequently due to different proportions of generated al-cu solid solution (α-al), al-al2cu eutectic and remained un-reacted al in the molten alloy, a functionally graded material was formed. the specimens subjected to optical microscopy (om), x-ray diffraction (xrd) studies and hardness measurements. it was found that the pouring temperature as well as the mold preheat temperature affected the resultant microstructure gradients in the samples via their effects on the cooling rates during solidification. moreover, the increased weight of solid copper resulted in shifting the hardness profiles towards higher values, while the gradient remained almost constant. it was concluded that three phenomena including melt convection, gravitational macro-segregation, and normal segregation governed the distribution of cu atoms towards different directions in the samples. however, due to the dominant effect of gravity, steeper microstructure and hardness gradients obtained along the vertical as compared with horizontal directions.