Ultrasonic Vibration Of 7050 Aluminum Alloy Melt Solidification Dynamics The Undercooling Impact

Treating aluminum melt by ultrasonic field is an effective method of improving casting ingot solidification structure and material mechanical property. It is the international research hotspot in nowadays and a new direction of future casting technique. This paper took 7050 aluminum ultrasonic casting as penetration point and the main study was shown as follows:1,Through carrying out the semi-continuous casting experiment of the 7050 aluminum melt, the effect of ultrasonic treatment on decreasing the dimension of crystal grain,grain refinement,reducing sub-phase, obtaining of fine equiaxed grain have been research.2,Through the crucible experiment of 7050 aluminum alloy ,the results show that: the time of crystallization was delayed with the increase of power and the actual crystallization temperature was decreased. At the same time, the actual crystallization temperature was measured, which offered certain theoretic referenced value for later research.3,Through the analysis and deduction of the mathematic model of the dynamic overcooling,we obtained the results that the vibration energy and frequency of the solidification front was correlative to the dynamic overcooling. Based on the knowledge of quantum mechanics, the mathematic expression of the vibration energy and frequency of the critical crystal-embryo was deduced and the specific values were measured. After ultrasonic field was injected into the aluminum melt, the ultrasonic energy was absorbing by the melts and the frequency of the critical crystal-embryo was increased. Thus it boosted the dynamic overcooling under the action of ultrasound. Combined with the front measured values of the actual crystallization temperature, the specific values of the dynamic overcooling with ultrasonic effect were measured. In the end, based on the developing model of the crystal and the difference of the measured dynamic overcooling, the change of the curvature radius of dendritic crystal's end was tiny and the slight change of the dynamic overcooling was not the main reason for the formation of the equiaxed grain.