Production of metal matrix composites ingots from semisolid alloys

Abstract
The working principle and the peculiarities of new electromagnetic rheocasters, which are based on the use of rotating permanent magnets and which allow the production of intense three-dimensional multiphase flows in solidifying semi-solid alloy slurries and metal matrix composites, are described. These processes are likely to be applied to the direct continuous casting of billets, tubes and slabs. They are also characterized by a very low electric power consumption. Local measurement techniques are applied to the study of the evolution of the fluid flow phenomena with the rotation speed of the inductor, the solid fraction, and the size and volume percent of SiC particles. A discussion is presented relating the metallurgical findings to the heat and fluid flow measurements. Satisfactory performances concerning the microstructure of solidified aluminum slurries and aluminum matrix composites (homogeneity, crystal shape, grain size, fraction of primary solid, distribution of SiC particles) were obtained.