Direct chill rheocasting (DCRC) of AZ31 Mg alloy

A new processing technology, direct chill rheocasting (DCRC), has recently been developed by BCAST at Brunel University, for production of high quality Mg alloy billets and slabs. In the present paper the authors present the DCRC process and experimental results on microstructure and mechanical properties of DCRC billets. Basically, the DCRC process consists of a high quality semisolid slurry supply system, continuously feeding a conventional direct chill caster, to produce billets or slabs. Experimental results show that the DCRC billets have a fine and uniform microstructure throughout the cross section, the average grain size being similar to 50 mu m. Direct extrusion of the DCRC billets was conducted to assess the deformability and mechanical properties after extrusion. The average grain size is < 3 mu m in the as extruded state. The increased deformability of the DCRC billets has been attributed to the fine and uniform microstructure, while the improved mechanical properties of the extruded product is attributed to the fine grain size.