System and filter for filtering hard alpha inclusions from reactive metal alloys

Abstract

A system for filtering hard alpha inclusions from a reactive metal alloy, such as titanium, is provided. The system includes a vessel, a receptacle and a filter. The vessel is capable of holding the reactive metal alloy in a molten form, and can pour the molten reactive metal alloy. The receptacle is for receiving the molten reactive metal alloy poured from the vessel. And to prevent at least some hard alpha inclusions from entering the receptacle, the filter is disposed between the vessel and the receptacle such that the molten reactive metal alloy passes therethrough before being received by the receptacle. The filter includes a frame, and a porous surface that is disposed within the frame. The porous surface defines openings that are sized to permit the reactive metal alloy in molten form to pass therethrough while capturing hard alpha inclusions.

What is claimed is:  
     
         1 . A system for filtering hard alpha inclusions from a reactive metal alloy, said system comprising: 
 a vessel capable of holding the reactive metal alloy in a molten form, wherein said vessel is capable of pouring the molten reactive metal alloy;    a receptacle for receiving the molten reactive metal alloy poured from said vessel; and    a filter disposed between said vessel and said receptacle through which the molten reactive metal alloy passes before being received by said receptacle for preventing at least some hard alpha inclusions from entering said receptacle, said filter comprised of a material having a melting point that exceeds a melting point of the reactive metal alloy and is at least partially insoluble in the molten reactive metal alloy.    
     
     
         2 . A system according to  claim 1  further comprising: 
 a heating element in thermal contact with said filter, wherein said heating element is capable of preheating said filter so as to limit solidifying of the molten reactive metal alloy on said filter as the molten reactive metal alloy passes therethrough.  
 
     
     
         3 . A system according to  claim 2  further comprising: 
 a chamber defining an internal cavity within which said vessel, receptacle and filter are disposed, wherein the internal cavity is isolated from an external environment, and wherein said heating element is capable of preheating said filter by passing current through said filter.  
 
     
     
         4 . A system according to  claim 2 , wherein said filter comprises a porous surface defining a plurality of openings, and wherein said heating element preheats said filter to thereby limit the solidifying of the molten reactive metal alloy within the openings defined by said porous surface of said filter.  
     
     
         5 . A system according to  claim 1 , wherein at least a portion of said filter comprises a refractory metal alloy including at least one of niobium, molybdenum, tantalum, rhenium and tungsten.  
     
     
         6 . A system according to  claim 1 , wherein said filter includes a porous surface defining a plurality of openings, and wherein the porous surface comprises a refractory metal.  
     
     
         7 . A system according to  claim 6 , wherein the refractory metal is selected from a group consisting of niobium, molybdenum, tantalum, rhenium and tungsten.  
     
     
         8 . A system according to  claim 1 , wherein the reactive metal alloy with a solvus temperature displaying a positive slope comprises titanium.  
     
     
         9 . A system according to  claim 1 , wherein said filter comprises: 
 a frame; and    a porous surface disposed within said frame such that said frame extends peripherally about said porous surface, wherein said porous surface defines a plurality of openings that are sized to permit the reactive metal alloy in molten form to pass therethrough.    
     
     
         10 . A system according to  claim 1 , wherein said filter comprises a material having a solubility less than a predetermined percent by weight in the molten reactive metal alloy.  
     
     
         11 . A system according to  claim 10 , wherein the material of said filter has a solubility less than twenty-five percent by weight in the molten reactive metal alloy.  
     
     
         12 . A system according to  claim 1 , wherein said filter comprises a material having a melting point greater than a melting point of the reactive metal alloy by at least a predetermined amount.  
     
     
         13 . A system according to  claim 12 , wherein the material of said filter has a melting point greater than a melting point of the reactive metal alloy by at least 500 degrees Celsius.  
     
     
         14 . A filter for filtering hard alpha inclusions from a reactive metal alloy, said filter comprising: 
 a frame; and    a porous surface disposed within said frame such that said frame extends peripherally about said porous surface, wherein said porous surface defines a plurality of openings that are sized to permit the reactive metal alloy in molten form to pass therethrough while separating at least some hard alpha inclusions therefrom, said porous surface comprised of a material having a melting point that exceeds a melting point of the reactive metal alloy and is at least partially insoluble in the molten reactive metal alloy.    
     
     
         15 . A filter according to  claim 14 , wherein said filter is formed of a thermally conductive material that is capable of being preheated so as to limit solidifying of the molten reactive metal alloy on the filter as the molten reactive metal alloy passes through said porous surface.  
     
     
         16 . A filter according to  claim 14 , wherein said porous surface comprises a refractory metal alloy including at least one of niobium, molybdenum, tantalum, rhenium and tungsten.  
     
     
         17 . A filter according to  claim 14 , wherein said porous surface comprises a refractory metal.  
     
     
         18 . A filter according to  claim 17 , wherein the refractory metal is selected from a group consisting of niobium, molybdenum, tantalum, rhenium and tungsten.  
     
     
         19 . A filter according to  claim 14 , wherein said porous surface comprises a material having a solubility less than a predetermined percent by weight in the molten reactive metal alloy.  
     
     
         20 . A filter according to  claim 19 , wherein the material of said porous surface has a solubility less than twenty-five percent by weight in the molten reactive metal alloy.  
     
     
         21 . A filter according to  claim 14 , wherein said porous surface comprises a material having a melting point greater than a melting point of the reactive metal alloy by at least a predetermined amount.  
     
     
         22 . A filter according to  claim 21 , wherein the material of said porous surface has a melting point greater than a melting point of the reactive metal alloy by at least 500 degrees Celsius.