Study On Growth Characteristics Of ZL114aalloy Eutectic Silicon Under Ultrasonic Vibration-Vacuum Counter-pressure

Al-Si alloy is widely used for its good mechanical properties,specific strength and corrosion resistance.However,Al-Si alloy is easy to form coarse dendrites and lamellar eutectic silicon structures under solidification conditions,thus affecting the organization and performance of aluminum alloy castings.Vacuum Counter-pressure casting is an advanced and precision counter-gravity forming method,can get the organization and performance of aluminum alloy castings.Ultrasonic treatment technology is an efficient,non-polluting physical refinement of the grain method.Combining the ultrasonic treatment technology with the vacuum counter-pressure casting technology,discussed the growth characteristics of the eutectic silicon under the ultrasonic vibration-vacuum counter-pressure casting,which can provide the theoretical guidance and stand by technology for the vacuum counter-pressure casting of high quality and complex thin-walled aluminum alloy castings.It takes the ZL114 A alloy as the research object,through analysis the aluminum alloy microhardness,eutectic silicon growth orientation and morphology under different ultrasonic power and solidification pressure of the vacuum counter-pressure casting,explore the growth characteristics of ZL114 A eutectic silicon of ultrasonic vibration-vacuum counter-pressure casting.The result showed that: ultrasonic power and solidification pressure have significant effects on microhardness,eutectic silicon growth orientation and morphology of aluminum alloy.When the solidification pressure is constant,the microhardness of ZL114 A alloy increases with the increase of ultrasonic power and then decrease.the best ultrasonic power is 600W;(111)and(220)of the eutectic silicon at 600 W are strongly inhibited,while the(311)plane favors disappear,and the eutectic silicon tends to be isotropic,so that the eutectic silicon is small and round.At the same ultrasonic power,the microhardness of ZL114 A alloy increases with the increase of solidification pressure,the eutectic silicon is more difficult to grow to the preferential(111),(220)and(331),so the eutectic silicon is finer.The optimal ultrasonic vibration-vacuum counter-pressure casting coordination parameters were ultrasonic power 600 W and solidification pressure 350 KPa,The mathematical relationship model between ultrasonic power,solidification pressure and microhardness was established under the ultrasonic vibration-vacuum counter-pressure casting coordination field.At the same time,the evolution model of eutectic silicon microstructure under ultrasonic vibration-vacuum counter-pressurecasting is established,and the mathematical model of cavitation extrusion under the action of ultrasonic vibration-vacuum counter-pressure casting is deduced:With the increase of cavitation squeeze infiltration?G,the effect of dendrites and eutectic silicon become more and more stronger,the microstructure of the aluminum alloy is more uniform and smaller.The results of this study provide a new approach for the application of Al-Si alloy in vacuum counter-pressure casting,which lays the theoretical and technical foundation for the application and popularization of composite field in vacuum counter-pressure casting aluminum alloy technology.