Evaporation Behavior of Al and Sn from Ti-6242 Alloy Melt
Hideo Mizukami, Tomoyuki Kitaura, Yoshihisa Shirai
For multi-component titanium alloy ingots that contain evaporable solute elements, the evaporation behavior of these elements is very important for optimizing the casting conditions. This study examined the evaporation of Al and Sn from molten Ti-6242, an alloy used for aircraft engines, after partial melting in a small electron beam furnace. The amount of Al and Sn evaporation depended on the melting time, there equilibrium vapor pressure of the elements and activity in the molten alloy. The concentration of Al changed in proportion to that of Sn in the molten alloy during evaporation process and the amount of evaporation of Al was twice as Sn. The rate control step of evaporation of Al and Sn were limited by evaporation from the molten alloy surface to the vacuum phase. The liquidus temperature of the alloy melt also changed with the evaporation of Al and Sn. These findings will help predict the amount of solute evaporation from molten titanium alloys and maintain the surface and internal quality of the ingots.
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ISIJ International Vol.52(2012), No.9