Fabrication and properties of functionally graded Al/AlB₂ composites

Abstract

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 C by adding boron oxide resulting in AlB 2 flakes 2.71-4.20% by weight before being cast centrifugally at 800 C. 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.

Casting and Applications of Functionally Graded Metal Matrix Composites

“…In a study, Ramadan and Omer fabricated FGAACs of varying fraction volumes of boron (1.2% to 1.85% wt), dispersed in Al, Al-Cu, and Al-Si alloys matrixes respectively, using CCT [56]. It was observed that B could only dissolve in aluminium alloys sufficiently at elevated tempera- [56].…”

“…It was observed that B could only dissolve in aluminium alloys sufficiently at elevated tempera- [56].…”

PRODUCIBILITY OF FUNCTIONALLY GRADED AlB2/Al COMPOSITE MATERIAL

“…Commercial Al-B master alloys are used as boron donors in the production of AlB 2 composites [8,9]. Commercial Al-B alloys are widely used as grain refiners in the casting of aluminum alloys and in the production of high conductivity conductor wire [10,11].…”

Fabrication of functionally graded composites using a homogenised low-frequency electromagnetic field

“…3,5 This technique can be used to obtain a linear concentration gradient of reinforcement for any composition of the reinforcement and matrix materials, provided there is a difference in their density. A method which also uses the difference in the density of materials is centrifugal casting, 6 which allows obtaining, depending on the orientation of the mould relative to the rotation axis, both linear gradient, 7,8 as well as radial gradient, [9][10][11] which is useful in such applications such as engine or compressor pistons, bearings elements. If the difference in the density of the material and the matrix is insufficient to achieve due to the action of gravity or the centrifugal force of the concentration gradient in the desired direction, other physical phenomena can be used (e.g.…”

“…Figure10. Division of the sleeve section into areas, used in the analysis of reinforcement fraction and bands, marked in grey, was taken into account when calculating the Feret diameter of particles.…”