An experimental study of aluminum boride particles distribution in centrifugally cast Al/AlB(x) composites.

摘要

In this research, centrifugal casting has been used to investigate the influence of casting parameters and chemical composition on the manufacturing of functionally graded Al-2 wt. %B-6 wt. %Mg and Al-2 wt. %B-6 wt. %Cu composites reinforced with aluminum boride particles. The resulting microstructure of the cast specimens were characterized both quantitatively and qualitatively via image J analysis to study the distribution of the reinforcement particles. An evaluation of the composite hardness was also conducted through the use of superficial Rockwell hardness and Vickers microhardness.;The microstructure analysis revealed the strong effect of varying centrifugal casting parameters on the redistribution of the reinforcement particles along the cylindrical casting axis, which was parallel to the centrifugal force. This distribution resulted in a compositional gradient of particles, with more particles towards the external zone than in the internal zone of the casting. The hardness analysis also reflects this tendency: higher superficial Rockwell hardness and a higher Vickers microhardness values towards the external zone.;Alloying elements Mg and Cu favored good wettability between the reinforcement particles and the aluminum matrix melt. This reduced the pores formation in the composites to a very little quantity, i.e. between the ranges of 0.01% to 2%. The presence of magnesium favored the partial transformation of AlB 12 particles into AlB2 in the Al-2 wt. %B-6 wt. %Mg composites. SEM/EDS analysis helped study the interaction of magnesium and copper levels on the reinforcement particles.