Double-stream-pouring technique for production of gradient materials by continuous casting

A novel method for producing gradient materials by continuous casting is introduced. By using many-stream-pouring technique, samples with gradient distribution of alloy composition along the cross section have been prepared. The main difference of this method from the conventional continuous casting is the pouring system equipped with two sets of tundishes for liquid metals of different alloy compositions. Special consideration is given to the promotion and control of the crass-sectional mass transport. The steady heat transfer and mass flow ensure a partial mixing of two metals and yield a continously varying composition distribution. By adjusting the processing parameters, composition profile with different shapes can be achieved. First experiments have been carried out in Al-Si system and Al-Cu system for three series of Al/AlSi, AlSi/Al and AlCu/Al. It is shown that the alloy composition, the microntructure and the mechanical property change smoothly from the centre to the surface of the samples. This simple and practical method is potential for mass prodution of “structural gradient materials” and may offer a new way for alloy design.