Effect of power ultrasonic on solidification microstructure of Al-Ni-Zn-Mg aluminum alloy

The effect of power ultrasonic on the solidification microstructure of a newly developed Al-Ni-Zn-Mg aluminum alloy has been investigated. The melt of the alloy was treated by ultrasonic field with different powers from 0W to 850W. Without high-energy ultrasonic treatment, the eutectic Al3Ni phases with coarse long dendritic-shape were observed in the aluminum matrix, and its size could be much more than 50μm. With the ultrasonic field of power more than 450W introducing into the melt, the morphologies of the Al3Ni phases were changed into short rod-shape or particle-shape and the distributions were nearly uniform. Meanwhile, the influence of ultrasonic treating time and ultrasonic treating temperature on the morphologies of the Al3Ni phases was studied. The results showed that ultrasonic treatment of the proper time such as 180s for the Al-Ni-Zn-Mg alloy could result in considerable improvement of the morphologies of the Al3Ni phases. The morphologies and the size of the eutectic Al3Ni phases were gradually improved with the increase of temperature from 680˚C to760˚C.