Process and apparatus for making thixotropic metal slurries
AssigneeInternational Telephone and Telegraph Corporation
InventorsJoseph Winter, Jonathan A. Dantzig, Derek E. Tyler
Life of this patent
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Abstract
A process and apparatus for forming a semi-solid thixotropic alloy slurry and preferably a rheocasting therefrom. Molten metal in a mold is cooled under controlled conditions while it is mixed under the influence of a moving magnetic field. A non-zero, magnetic field is provided across the full cross section of the mold and over the entire solidification zone. This results in a magnetomotive stirring force of sufficient magnitude to provide mixing of the molten metal to form the slurry. Preferably, a two pole induction motor stator is used to generate the magnetic field.
Claims23
In an apparatus for continuously or semi-continuously forming a semi-solid thixotropic alloy slurry, said slurry comprising throughout its cross section degenerate dendrite primary solid particles in a surrounding matrix of molten metal, said apparatus comprising:
- means for containing molten metal, said containing means having a desired cross section;
- means for controllably cooling said molten metal in said containing means;
- and
- means for mixing said molten metal for shearing dendrites formed in a solidification zone as said molten metal is cooled for forming said slurry;
- the improvement wherein said mixing means comprises:
- a single two pole stator for generating a non-zero rotating magnetic field which moves transversely of a longitudinal axis of said containing means across the entirety of said cross section of said containing means and over said entire solidification zone, said moving magnetic field providing a magnetomotive stirring force directed tangentially of said containing means for causing said molten metal and slurry to rotate in said containing means, said magnetomotive force being of sufficient magnitude to provide said shearing of said dendrites, said magnetomotive force providing a shear rate of at least 500 sec..sup.-1.
In a process for continuously or semi-continuously forming a semi-solid thixotropic alloy slurry, said slurry comprising throughout its cross section degenerate dendrite primary solid particles in a surrounding matrix of molten metal, said process comprising:
- providing a means for containing molten metal having a desired cross section;
- controllably cooling said molten metal in said containing means;
- and
- mixing said contained molten metal for shearing dendrites formed in a solidification zone as said molten metal is cooled for forming said slurry;
- the improvement wherein said mixing step comprises:
- generating solely with a two pole stator a non-zero rotating magnetic field which moves transversely of a longitudinal axis of said containing means across the entirety of said cross section of said containing means and over said entire solidification zone, said moving magnetic field providing a magnetomotive stirring force directed tangentially of said containing means for causing said molten metal and slurry to rotate in said containing means, said magnetomotive force being of sufficient magnitude to provide said shearing of said dendrites, said magnetomotive force providing a shear rate of at least 500 sec..sup.-1.
Dependencies are inferred from the claim text.