Mechanical Properties Study On Ultrasonic Vibration Tension Of SiCp/Al Composites With High Volume Fraction

Silicon carbide particle reinforced aluminum matrix composites(SiCp/Al)have been widely used in military,aerospace and electronic packaging fields due to their special mechanical properties and physical properties.Compared with the traditional processing methods,ultrasonic vibration composite processing has shown great advantages in the processing of SiCp/Al composites,but its removal mechanism and surface layer formation mechanism under ultrasonic vibration conditions are still unclear.Related studies have shown that after applying ultrasonic vibration,some materials will have special mechanical behaviors such as ultrasonic softening effect,ultrasonic residual hardening effect and ultrasonic residual softening effect.Therefore,it is necessary to study the influence of ultrasonic vibration on the mechanical behavior of SiCp/Al composites and lay a foundation for subsequent research.The main research contents and experimental results of this paper are as follows:(1)Based on the viscoelastic-plastic constitutive model,the stress superposition effect,the softening effect and the Hall-Petch strengthening effect are considered to establish the stress-strain model of ultrasonic vibration tension.According to the theory of stress wave propagation,the resonant dumbbell type specimens with different materials were designed and the ultrasonic vibration tensile test device was developed.The tested vibration performance was excellent.(2)The ultrasonic vibration uniaxial tensile test was carried out by using the test device.The effects of ultrasonic frequency,amplitude and vibration process on the stress reduction amplitude and fracture strength of SiCp/Al composites were studied.The fracture macroscopic appearance and microscopic appearance of the material were observed.The results show that the stress variation of the material under ultrasonic vibration is obviously divided into three stages.The stress superposition effect and the softening effect exist simultaneously with the Hall-Petch strengthening effect,and the proportions of different stages are different.As the ultrasonic frequency and amplitude increase,the stress reduction increases,mainly because the softening effect is the main factor.The longer the ultrasonic action time,the higher the frequency and amplitude,and the lower the breaking strength of the material.The microscopic morphology shows that the fracture of the material has brittle fracture and ductile fracture.The dimple fracture was observed in the aluminum alloy matrix.Under conditions of ordinary tensile,the SiC particles mainly have interface debonding,and the SiC particles are more likely to undergo cleavage fracture during the ultrasonic vibration tensile.Ultrasonic vibrations cause more cracks inside the material,resulting in a decrease in the overall fracture strength of the material.(3)Based on the tensile test,the ultrasonic vibration tensile simulation research is carried out.The research shows that there have stress superposition effect and softening effect in the simulation process.The Hall-Petch enhancement effect cannot be reflected in the simulation process due to the inability to simulate the variation of dislocations,which also leads to the same trend of the simulation results and the overall trend of the test results,but there exist error.Through the range analysis method of orthogonal test,the order of the main factors is: ultrasonic amplitude,tensile rate and ultrasonic frequency,which provides a reference for the subsequent experiments.