Microstructures of DC Cast Light Alloys under the Influence of Intensive Melt Shearing
A new direct chill (DC) casting process, melt conditioned DC (MC-DC) process has been developed for production of high quality ingots and billets of light alloys. In the MC-DC casting process, intensive melt shearing provided by a newly developed rotor-stator unit is used to control the solidification process during the DC casting with a conventional DC caster. Experimental results of DC casting of Al- and Mg-alloys with and without intensive melt shearing have demonstrated that the MC-DC casting process can produce light alloy billets with significantly refined microstructure and substantially reduced cast defects. The effect of intensive melt shearing on grain refinement has been mainly attributed to the enhanced heterogeneous nucleation on well dispersed oxides occurring naturally in the alloy melt.