Degassing of aluminum alloys via the electromagnetic directional solidification

• A new route for degassing of molten aluminum alloys was put forward.
• The degassing feasibility and mechanism have been analyzed.
• A model of the degassing was set up.
• It has potential applications for the fabrication of high quality aluminum alloys.

A new route for degassing of molten aluminum alloys has been developed via the electromagnetic directional solidification. We evaluated the degassing feasibility and mechanism for the formation and evolution of the porosity. As expected, it enabled the migration of porosity to the upper end instead of the distribution in the whole sample. Furthermore, we investigated the effects of various pull-down rates, i.e., solidification rates on the degassing efficiency, porosity area fraction, and microstructure of alloys, etc. Clearly, the experimental results show that with the reducing of pull-down rates, the degassing efficiency increases and the porosity area fraction decreases, respectively. The lowest porosity area fraction is down to 0.08% under the 5 μm/s pull-down rate. Simultaneously, there are almost no porosity and other defects in the lower part of the final product. In conclusion, it offers an alternative method for degassing and possesses potential applications in aeronautic and space industry.