7075/6009 gradient materials were prepared by continuous casting using double-stream-pouring technique. The effects of throttle bore diameter of submerged embedded nozzle on composition

macrostructure and Rockwell hardness of the alloys were investigated. Main attention is paid to the interface characteristics of the alloy ingot. The results show that there is a transition layer about 5 mm in thickness in the alloy ingot. The interface boundary between external layer and transition layer is clear. However

the interface boundary between internal layer and transition layer is difficult to clarify. With the increase in the throttle bore diameter

the thickness of the external layer of the developed alloy increase but the throttle bore diameter has little effect on the thickness of the transition layer.