PURPOSE: To remove the contained impurity element in a short time by deposition, by heating a molten Mg-Al alloy at a high temp. below the temp. at which the solidification of the alloy is started.
CONSTITUTION: Impurity iron (by about 0.02wt.%) is removed from an Mg alloy (about 600°C solidification starting temp.) contg., for example, 9wt.% Al, 0.7wt.% zinc and 0.3wt.% Mn. In this case, the alloy is heated to about 750°C in the (Ar+0.2% SF6) gas atmosphere while preventing the combustion of Mg and completely melted. The molten alloy is kept at 590°C which is lower than the temp. where the solidification of the molten alloy is started, and the iron concn. is reduced to about 0.001wt.% in about 30min. Consequently, the impurity is removed in a short time without using a special molten metal holder, etc.
NISHI SEIJI
ONOE TOSHIO
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