Method of refinement of microstructure of metallic materials

Abstract

The present invention provides a method for refining microstructure of metallic materials and the present invention relates to a method in which cavitation (cavities) is formed in molten metal by the application of high-energy vibrating force to a metal in the process of solidification, and the newly formed solid crystal particles are crushed by the impact pressure generated during the collapse of the cavities to refine the microstructure of the material, and high-energy electromagnetic vibrating force is applied to a solidifying metal sample 10 by the simultaneous imposition of an electric current and a magnetic field in an apparatus comprising an electromagnet 12 for applying a stationary magnetic field and an electrode 11 for passing an alternating current through the metal sample, so that the solid crystal particles are crushed into small pieces, yielding a fine microstructure thereof.

1 - 14 . (canceled)  
   
   
       15 . A method for shifting a refined microstructure of a metallic material, comprising: 
 solidifying a molten metallic material at temperatures lower than a liquidus of the molten metallic material; and    vibrating the solidifying molten metallic material by applying an alternating electric current and a magnetic field simultaneously at a current value and a Tesla value configured to crush solid crystal particles of the solidifying metallic material into small pieces; and    shifting the small pieces to a periphery of a cylindrical tube or container with said alternating current and said magnetic field set at a current value and a Tesla value configured to concentrate said refined microstructure of the metallic material in the periphery of the cylindrical tube or container.    
   
   
       16 - 17 . (canceled)  
   
   
       18 . The method of  claim 15 , wherein the applying further comprises applying the electric current and the magnetic field during last stages of solidifying of the solidifying metallic material.  
   
   
       19 . (canceled)  
   
   
       20 . The method of  claim 15 , wherein the magnetic field is generated with an electromagnetic coil enveloping the metallic material.  
   
   
       21 . The method of  claim 15 , wherein said current value and said Tesla value configured to crush solid crystal particles comprises: 
 a current value less than a current value used to melt said metallic material.    
   
   
       22 . The method of  claim 15 , wherein said current value and said Tesla value configured to concentrate said refined microstructure comprises: 
 a Tesla value of 1.4 Tesla.    
   
   
       23 . The method of  claim 15 , wherein said metallic material is Al—Si alloy and said small pieces have a crystal grain diameter between 0.5 and 3 μm.  
   
   
       24 . The method of  claim 15 , wherein said metallic material is Al—Si alloy with silicon carbide particles dispersed therein and said small pieces comprise small silicon carbide particles having a crystal grain diameter between 0.1 and 2 μm.  
   
   
       25 . The method of  claim 15 , further comprising: 
 concentrating said metallic material in an end portion of said metallic material by moving the metallic material within the magnetic field.