Study of Casting Parameters and Magnesium Effects on the Distribution of Boride Particles during Centrifugal Casting of functionally graded Aluminum Matrix Composite

摘要

An experimental investigation of the effect of casting parameters during the fabrication of functionally graded Al-B- Mg (AI-2 wt. % B- 6 wt. % Mg) composites via centrifugal casting method has been conducted. Particular interest was dedicated to the transformation of the dodecaboride particles into complex aluminum diboride particles and the redistribution of these particles on the matrix of the composites. Pertinent image analysis permitted characterizing the resulting composite microstructures both quantitatively and qualitatively. Our results revealed that as casting time, rotational speed and pouring temperature of the melt increased, the concentration of the reinforcement particles becomes denser at the outer periphery of the casting. The data obtained from both superficial Rockwell hardness and Vickers microhardness analysis demonstrated that both mechanical properties bore similar trend as the gradient in particles distribution. Additionally, backscattered electron imaging helped differentiate the morphology and apparent composition of the aluminum boride particles with different levels of boron. The interaction of the magnesium levels in the composite matrix and the reinforcement particles via energy dispersive spectroscopy is also discussed.