Fabrication and properties of functionally graded Al/AlB2 composites

In the present study, an AlB2-reinforced functionally graded aluminium matrix composite has been produced by centrifugal casting. Boron 1.2-1.85% by weight has been dissolved in aluminium at 1400? by adding boron oxide resulting in AlB2 flakes 2.71-4.20% by weight before being cast centrifugally at 800?. Results showed that there were two distinct regions without a smooth grading: one is rich of AlB2 and the other is poor of AlB2. The highest AlB2 content has been found to be around 11% in outer zones, whereas the lowest AlB2 content has been observed to be below 0.02% in inner zones. Results also showed that, depending on the increase in the reinforcement phase in outer zones, up to 64% increase in the strength and hardness of the composite has been achieved.