Metallic materials for rheocasting or thixoforming and method for manufacturing the same

Abstract

A method for manufacturing a metallic material for rheocasting or thixoforming and a metallic material formed using the method are provided. The method includes: applying an electromagnetic field to a vessel and loading a molten metal into the vessel; and cooling the molten metal to form a metallic material for rheocasting or thixoforming. The entire volume of molten metal is rapidly and uniformly cooled throughout, from the wall toward the center of the vessel, without generating latent heat caused by the formation of solidification layers at the early stage of cooling. The molten metal in the vessel is cooled rapidly below its liquidus temperature within 1-10 seconds after the loading of the molten metal into the vessel, so that numerous uniform crystal nuclei are created throughout the entire volume of molten metal to form a metallic material having uniform, micro, spherical particles.

What is claimed is:  
     
         1 . A method for manufacturing a metallic material for rheocasting or thixoforming, comprising: 
 applying an electromagnetic field to a vessel and loading a molten metal into the vessel; and    cooling the molten metal to form a metallic material for rheocasting or thixoforming.    
     
     
         2 . The method of  claim 1 , wherein the electromagnetic field is applied prior to the loading of the molten metal into the vessel.  
     
     
         3 . The method of  claim 1 , wherein the electromagnetic field is applied simultaneously with the loading of the molten metal into the vessel.  
     
     
         4 . The method of  claim 1 , wherein the electromagnetic field is applied in the middle of the loading of the molten metal into the vessel.  
     
     
         5 . The method of  claim 1 , wherein the application of the electromagnetic field is stopped when the molten metal has a solid fraction of 0.001-0.7.  
     
     
         6 . The method of  claim 1 , wherein the application of the electromagnetic field is stopped when the molten metal has a solid fraction of 0.001-0.4.  
     
     
         7 . The method of  claim 1 , wherein the application of the electromagnetic field is stopped when the molten metal has a solid fraction of 0.001-0.1.  
     
     
         8 . The method of  claim 1 , wherein the metallic material is in the form of slurries or billets.  
     
     
         9 . The method of  claim 1 , wherein the molten metal is loaded into the vessel in a temperature range between a liquidus temperature of the molten metal and 100° C. above the liquidus temperature.  
     
     
         10 . The method of  claim 1 , further comprising a secondary forming process for the metallic material after cooling the molten metal.  
     
     
         11 . The method of  claim 10 , wherein the secondary forming process for the metallic material includes die casting, squeeze casting, forging, and pressing.  
     
     
         12 . The method of  claim 8 , further comprising remelting the billets back to semi-solid or semi-molten state for a secondary forming process.  
     
     
         13 . The method of  claim 1 , wherein the molten metal is cooled until the molten metal has a solid fraction of 0.1-0.7.  
     
     
         14 . The method of  claim 1 , wherein the molten metal is cooled at a rate of 0.2-5° C./sec.  
     
     
         15 . The method of  claim 1 , wherein the molten metal is cooled at a rate of 0.2-2° C./sec.  
     
     
         16 . The method of  claim 1 , wherein the molten metal is selected from the group consisting of aluminum, magnesium, zinc, copper, iron, and alloys of the forgoing metals.  
     
     
         17 . A metallic material for rheocasting or thixoforming in the form of slurries or billets manufactured according to the method of  claim 1 , the metallic material having spherical particles with uniform distribution.  
     
     
         18 . The metallic material of  claim 17 , wherein the spherical particles of the metallic material have an average diameter of 10-60 μm.