C. Vives, ELABORATION OF METAL-MATRIX COMPOSITES FROM THIXOTROPIC ALLOY SLURRIES USING A NEW MAGNETOHYDRODYNAMIC CASTER, Metallurgical transactions. B, Process metallurgy, 24(3), 1993, pp. 493-510
The working principle and the peculiarities of a new electromagnetic r
heocaster, which is based on the use of rotating permanent magnets and
which allows the production of intense three-dimensional (3-D) multip
hase flows in solidifying semisolid alloy slurries and metal matrix co
mposites, are described. This process can be applied to the direct con
tinuous casting of billets, tubes, and slabs and is characterized by v
ery low electric power consumption. Local measurement techniques are a
pplied to the study of the evolution of non-Newtonian magnetohydrodyna
mic multiphase flow phenomena with the rotational speed of the inducto
r, the solid fraction of the aluminum alloy matrix, and the size and v
olume percent of SiC particles. An order of magnitude analysis of the
various forces acting on the suspended crystals and SiC particles is g
iven. The rheological behavior of electromagnetically rheocast ferrous
metals, simulated by a lead-tin alloy, is also investigated. Satisfac
tory results concerning the microstructure of solidified aluminum slur
ries and aluminum matrix composites (homogeneity, crystal shape, grain
size, fraction of primary solid, and distribution of SiC particles) w
ere obtained. A discussion is presented relating the metallurgical fin
dings to the heat and three-phase flow measurements.