Study On The Mechanical Properties And Dimensional Stability Of SiC_p/2024Al Composites Containing Interlayer Defects

The interlayer defects are generated in the squeeze casting process of SiCp/2024Al composites. The effect of interlayer defects on the strength of the material has not been studied as so far. So we can not determine the allowable limit of composite materials with interlayer defects. Therefore, we can not develop national standards. This paper studied the effect of interlayer defects with different thicknesses as well as different direction on the mechanical properties and dimensional stability of SiCp/2024Al composites through the bending tests, tensile tests and dimensional stability tests. The angle between the interlayer defects and the axial direction of test sample is selected in30°,45°,90°.The bending strength of SiCp/2024Al composites with no interlayer defects is867.8MPa. The bending strength of composites with interlayer defects has the following relationship with the thickness and direction of the interlayer defects:With the thickness of interlayer defects in the same direction increases, the bending strength of the composites declines in the form of exponent. When the thickness is a constant value, the effect of interlayer defects in the direction of30°and90°on the strength of the composite material is closer, which is smaller than the effect of interlayer defeces in the direction of45°The tensile strength of SiCp/2024Al composite materials with no interlayer defects is544.4MPa. The tensile strength of composites with interlayer defects has the following relationship with the thickness and direction of the interlayer defects:With the thickness of the interlayer defects increases, the tensile strength of the composites declines in the form of exponential. When the thickness of interlayer defects is in a constant value, the interlayer defects with the45°direction has the minium tensile strength, and the90°direction followed by, then the30°direction has the greatest impact on the composite tensile strength.The interlayer defects have a greater impact on the distribution of stress field under tensile load of SiCp/2024Al composites. The stress concentration is generated in the vicinity of the interface between the composites and the interlayer defects. And the stress concentration factor increases with an exponential trend as the thickness of the interlayer defects increase. There is a great residual stress in the SiCp/2024Al composites with interlayerdefects after heat treatment. The residual stress increases gradually as the thickness ofinterlayer defects increases when the direction of interlayer is30°，while the residualstress decreases when the direction is45°and90°.The dimensional stability of SiCp/2024Al composites with interlayer defects whosedirection is30°and45°decreases with the increases of thickness of interlayer defects.As for the SiCp/2024Al composites with interlayer defects whose direction is90°，thedimensional stability substantially unchanged with the thickness of interlayer defectincreases.