Preparation And Microstructure And Properties Of ?SiC-Al₃Ti?/7075Al Composites

SiC particle reinforced aluminum-based?SiC/A1?composites have good comprehensive performance and are widely used in aerospace,defense,automotive and marine equipment,but the poor bonding and low performance of SiC interface in composite materials have affected their widespread use.In the method of preparing the SiC/Al composite material,the advantages of the agitation casting method,such as less process flow,simple operation,and low production cost,are widely concerned.However,the current SiC/A1 composites prepared by the stirring casting method have problems such as poor wettability,poor uniform dispersion,poor interfacial bonding strength and many pores.Therefore,the wettability of Ti content in SiC particles in A1-Ti alloy was studied.The effect of SiC-Ti-Al composite powder prepared by ball milling pre-dispersion on SiC morphology and SiC content in composites was studied.The dispersibility of SiC particles was studied by stirring process parameters.The bonding strength of ultrasonic treatment to the interface of composites was studied.Based on this,the microstructure of?SiC-Al₃Ti?/7075A1 composites with different SiC content prepared by high-energy ultrasonic liquid agitation was studied.Hardness,room temperature and wear resistance at 200°C and thermal compression deformation have important practical significance.In this paper,7075 is used as the base alloy,Ti is used as the active element,and SiC particles are added to prepare?SiC-Al₃Ti?/7075A1 composite material to improve its performance.The microstructure of A1-Ti-SiC composite powders with different Ti contents was studied.The results show that the active element Ti can improve the angular and roundness of the SiC particles.The microstructure and actual SiC content of aluminum matrix composites with different Ti contents were studied.The results show that the Ti element exists in the composite material with Al₃Ti phase,and the Al₃Ti phase plays a role in improving the wettability between SiC particles and aluminum liquid.When the Ti content is 2.0wt.%,the SiC particles in the composite structure are obvious.Increased,and the actual content reached a maximum of 3.04wt.%,but the agglomeration phenomenon was serious.The effect of Ti content and temperature on the wetting behavior of A1-Ti alloy in single crystal SiC was studied.The results show that the final contact angle decreases with the increase of Ti content at 1173K.The final contact angles of the three groups of pure aluminum,0.5wt.%and2.0%wt.Ti content of A1-Ti alloy are 79.4°,77.9°and 44.5°,2.0wt.%Ti content of the A1-Ti alloy is lower than the pure aluminum contact angle by 43.9%,2.0wt.%Ti content of the A1-Ti alloy in the single crystal SiC has the best wetting effect.On the basis of the wetting test results of A1-Ti alloy with 2.0wt.%Ti content,the final contact angle gradually decreased with the increase of temperature,and the final contact angles at 1073K,1123K,1173K and 1223K were 133.7°respectively,94.4°,44.5°,and 15.8°,the final contact angle of2.0 wt.%Ti at 1223 K to the A1-Ti alloy at 0.5 wt.%Ti content was reduced by 88.2%.Therefore,the wetting effect of A1-Ti alloy with 2.0wt.%Ti content at 1223K is best.Therefore,the optimum addition amount of the composite material Ti is 2.0 wt.%.The effects of stirring parameters on the distribution of SiC,actual SiC content,density and hardness in?SiC-Al₃Ti?/7075Al composites were investigated by orthogonal experiments.Stirring parameters can affect the distribution of SiC,actual SiC content,density and hardness in the composite.The optimum stirring process parameters were obtained by range analysis and comprehensive performance analysis:stirring temperature was 800°C,stirring speed was 450 r/min,and stirring time was 20 min.It was verified by a confirmatory experiment.The effect of high energy ultrasound on the microstructure and properties of the composite was investigated.The quantitative analysis of the composite material prepared by high-energy ultrasonic liquid agitation by quantitative metallographic method shows that the porosity and porosity in the composite material are reduced,the agglomeration of SiC particles is reduced,the pores are smaller,and the hardness is improved.The microstructure,hardness,room temperature and high temperature wear resistance and hot compressive deformation ability of?SiC-Al₃Ti?/Al7075 composites with different SiC content prepared by high-energy ultrasonic liquid agitation were studied.With the increase of SiC content,the SiC phase in the composite increases obviously,and the hardness of the composite increases gradually.The SiC content of 5wt.%is increased by 17.16%compared with the 1wt.%hardness value,and the room temperature and high temperature wear resistance of the composite are improved.At room temperature,the average friction coefficient of SiC content of 5wt.%to 1wt.%is reduced by 33.9%,the wear amount is reduced by 71.06%,the SiC content of 5wt.%at 200°C is reduced by 43.75%compared with1wt.%,and the wear amount is reduced.62.04%,the wear morphology of the composites was analyzed by scanning electron microscopy.It was revealed that the friction mechanism at room temperature was mainly abrasive wear and accompanied by adhesive wear.The high temperature friction mechanism was mainly oxidative wear with a certain degree of abrasive wear.With the increase of SiC content,the maximum compressive strength of the composite material is significantly improved.