MICROSEGREGATION OF DIRECT CHILL INGOT OF SUPER HIGH STRENGTH ALUMINUM ALLOY CAST FROM HEAVILY ELECTROMAGNETICALLY STIRRED MELT

摘要

Low frequency electromagnetic casting (LFEC) applied to Al alloys produces intensive stirring in direct chill (DC) melt, which prevents hot cracking of high strength aluminum alloys never manufactured by DC. For instance, Al-10%Zn-2.7Mg-2.3Cu alloy, of which extruded and heat treated alloy show 780MPa in tensile strength and 13% in elongation, is able to produce by LFEC because of fine grain size due to heavy stirring and its grain size is small enough, such as 45 μm cast into 200 mm diameter billet. Not only to control this new casting well but also to develop alloy designing properly it is necessary to understand microscopic solidification behavior. Therefore, in this report, microsegregation in accordance with solidification progress including formation of various kinds of intermetallic compounds is firstly discussed by both precise experiments and the prediction by using thermodynamic data base.