Process and apparatus for continuous slurry casting

A heat exchanger for removing heat from a molten material and forming a semi-solid slurry, said heat exchanger comprising:

• first chamber means for containing said molten material;
• means for controlling the amount of said heat extracted from said molten material and the cooling rate of said molten material, said controlling means comprising a plurality of members formed from a material having a relatively low thermal conductivity lying in a plurality of circumferential planes;
• each said circumferential plane having at least one of said members and an enclosing material having a higher thermal conductivity defining an effective heat transfer area defined by that portion of said circumferential plane not encompassing said at least one member;
• said effective heat transfer area of a most upstream one of said planes being greater than said effective heat transfer area of a most downstream one of said planes;
• and
• insulating means lying between adjacent ones of said circumferential planes and being formed from a material having a relatively low thermal conductivity,
• whereby said molten material is cooled so as to initiate growth of primary phase particles of said molten material and to form sid semi-solid slurry, said semi-solid slurry having a fraction solid comprising said particles sufficient to form a cast structure having a non-dendritic structure across substantially its entire cross section.