Prepare The Homogeneous Al Based Immiscible Alloys By A Cooling Slope Method

As an important metal material, immiscible alloy (Monotectic Alloy) has extensive application in industry. However, the components of immiscible alloy are hardly miscible and very easy to be separated as layers by traditional casting methods. An obvious character of immiscible alloy is that there's a bow-shape immiscible zone in the phase diagram. When the solidification comes to this zone, the two liquid phases with different densities will depart quickly forming the severe macro segregation or components on different layers. Therefore, it is difficult to prepare the homogenous immiscible alloys by traditional casting technology.This work prepared Al based immiscible alloys by using a cooling slope method. In this method, the melted alloy's temperature was kept 20°C higher than the immiscible temperature for 30min, and it's determined according to the phase diagram and a great deal of experiments. This paper changed the cast cooling slope's length and angle to get different samples. By analyzing the macro-micro structures, it shows: the pouring position at 700mm and inclined angle at 45°are the best parameters for getting the homogenous immiscible alloy slurry. Then the immiscible alloy slurry is formed by using a water-bath copper mold or a diecasting machine. Finally, the homogenous immiscible alloys can be obtained.In this paper, the forces Bi drops suffered are analyzed in detail. The results show that Marangoni force, gravity, viscous force and scouring force restrained each other, so that the Stokes deposition and Marangoni moving are reduced. This software ANSYS? was employed to simulate the temperature distribution of the melt flowing on the cooling slope. The simulated results show that the temperature has a sharp decrement after passing through the cooling slope.In order to study the mechanism of phase separation of immiscible alloy, the synchrotron radiation imaging method was applied to obtain the real time solidification process. For simplicity, the low melting point Sn-20wt%Bi binary alloy was firstly tried and the images of dendritic growth were obtained with the Beijing synchrotron radiation source. The synchrotron imaging experiments for Al-Bi immiscible alloy has not been done in this study due to the time limitation and will be done in near future.