Patent ID: 7140419
Filing Date: 2006-11-28
Classification: B22D,C22C,Y10S

Abstract:
1. A method for processing a metallic alloy having a liquidus temperature and a solidus temperature, the method comprising the steps of providing the metallic alloy having a semi-solid range between the liquidus temperature and the solidus temperature of the metallic alloy; heating the metallic alloy to an alloy initial elevated temperature above the liquidus temperature; reducing the temperature of the metallic alloy from the initial metallic alloy elevated temperature to a semi-solid temperature of less than the liquidus temperature and more than the solidus temperature, wherein the step of reducing the temperature includes the steps of and maintaining the metallic alloy at the semi-solid temperature for a sufficient time to produce a semi-solid structure in the metallic alloy of a globular solid phase dispersed in a liquid phase, wherein said crucible has a predetermined mass, heat capacity and initial temperature and a predetermined quantity of said metallic alloy is provided at a predetermined initial temperature above the liquidus temperature of the alloy, said predetermined temperature, quantity, mass, heat capacity and initial temperature being selected such that said temperature at which said thermal equilibrium is reached is between the liquidus and solidus temperatures of the alloy, and wherein the predetermined mass, heat capacity and initial temperature of said crucible and said semi-solid temperature define an enthalpy chance of the crucible, and the alloy predetermined initial temperature and the mass and heat capacity of said predetermined quantity of the alloy and said semi-solid temperature together with the fraction of the quantity of alloy that has solidified at the semi-solid temperature and the heat of fusion of transformation of the alloy from liquid to solid define an enthalpy change of the quantity of metallic alloy poured into the crucible, such that the enthalpy changes of the quantity of metallic alloy and the crucible differ only by the radiative and convective heat losses from the surface of the crucible.