Abstract:

In order to improve the strength of short carbon fibers reinforced aluminum matrix (Csf/Al) composite, the dispersion of short carbon fibers with multi-orientation was controlled with a square crucible by mechanical stirring. The three-dimensional flow field models of liquid aluminum melt in the square/round crucibles were established and calculated, and the results were compared. The calculated results show that turbulent flow could be induced both in the square and round crucible, while the non-axisymmetric structure of the square crucible results in higher turbulent kinetic energy in the melt. Therefore, the uniformity and multi-orientation dispersion of the short fibers can be improved by the intensive turbulent flow in the square crucible, which will be increased by increasing the rotational velocity. The distribution of the short carbon fibers in the aluminum matrix prepared under different rotation velocities in square crucible was experimentally investigated. With the increase of stirring velocity, the multi-orientation dispersion of the short fibers in the composites increased gradually. The experimental results are consistent with the calculation results. The tensile testing results show that the strength of the Csf/Al composite can reach 172 MPa when the rotational velocity is 1000 rpm, and it is 48.3% higher than that prepared by the round crucible under the same conditions, which results from the improved multi-orientation dispersion of short carbon fibers in aluminum matrix.

Key words: Square crucible, Short carbon fibers, Aluminum matrix composite, Mechanical stirring, Multi-orientation dispersion