Fabrication and properties of functionally graded Al/AlB 2 composites

In the present study, an AlB 2 -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 AlB 2 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 AlB 2 and the other is poor of AlB 2 . The highest AlB 2 content has been found to be around 11% in outer zones, whereas the lowest AlB 2 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.