The effect of carbon fibers distribution on fracture behavior of carbon fiber reinforced aluminum matrix composites prepared by ultrasonic vibration

Controlling the distribution of carbon fibers(CFs) in the matrix has important influence on obtaining the composites with excellent properties. In this paper, the distributions of CFs under different amplitudes and the fracture behavior of the composites during tensile process were investigated. The results show that the amplitude has an important effect on infiltration behavior of aluminum melt into carbon fiber bundle and the distribution of CFs in the matrix. With the increase of amplitude, the fibers bundle can be completely infiltrated, and the carbon fiber distributes evenly in the matrix. However, excessive amplitude will cause the flow velocity to exceed the turbulence threshold and the CFs cannot be evenly distributed in the matrix to generate fiber cluster defects. CFs can be uniformly distributed in the matrix at an amplitude between 37 μm and 39 μm. In this case, the fibers can bear the larger load, and the tensile strength can reach 172 MPa. As well as the effect of carbon fiber distributions in the matrix on the fracture behaviors of composites were elaborately analyzed. The CFs changed from uniform distribution to partial fiber clusters, the fracture behavior changed from single fibers pullout to fiber bundles pullout state. The inhomogeneous distribution of CFs and the existence of defects in the fiber clusters would reduce the properties of the composite by 10% compared to the uniform distribution of carbon fibers in the matrix.