Method and apparatus for making high strength metals with a face-centered-cubic structure

Abstract

A process for increasing the strength of pure copper and other fcc matrix alloys. The method is particularly applicable to face-centered-cubic materials that undergo dynamic recovery when strain-hardened at room temperature. A cryogenic strain hardening process is used to create a high strength pure copper or copper+Al 2 O 3 alloy. The strength of the material is substantially increased. However, the loss of conductivity is minimal. In the preferred embodiment, pure copper or a copper alloy is drawn into a wire at a temperature of about 77 K. Dynamic recovery of the material is substantially reduced. With this method, drawn copper wire exhibits a strength level about 45% higher than that achievable by an equivalent room temperature deformation.

1 . A method for strain hardening a length of metal while reducing dynamic recovery, comprising:
 a. providing a vessel containing a cryogenic liquefied gas;   b. providing a deformation die, located within said vessel and immersed in said cryogenic liquefied gas; and   c. passing said length of metal through said deformation die while a portion of said length of metal proximate said deformation die and said deformation die remain immersed in said cryogenic liquefied gas.   
   
   
       2 . A method of strain hardening as recited in  claim 1 , wherein said cryogenic liquefied gas is liquid nitrogen. 
   
   
       3 . A method of strain hardening as recited in  claim 1  wherein said length of metal is a wire and said deformation die is a diameter reducing die. 
   
   
       4 . A method of strain hardening as recited in  claim 3 , wherein said wire is fed from a payoff reel, through said diameter reducing die, and onto a draw reel. 
   
   
       5 . A method of strain hardening as recited in  claim 4 , wherein said payoff reel is contained within said vessel and said draw reel is located outside said vessel. 
   
   
       6 . A method of strain hardening as recited in  claim 4 , wherein both said payoff reel and said draw reel are located outside said vessel. 
   
   
       7 . A method of strain hardening as recited in  claim 6 , wherein said wire is fed from said payoff reel to a first idler pulley, then through said diameter reducing die, then to a second idler pulley, and then to said draw reel. 
   
   
       8 . A method of strain hardening as recited in  claim 7 , wherein said first and second idler pulleys are contained within said vessel. 
   
   
       9 . A method for strain hardening a length of metal while reducing dynamic recovery, comprising:
 a. providing a volume of cryogenic liquefied gas;   b. providing a deformation die;   c. immersing said deformation die in said volume of cryogenic liquefied gas; and   d. using said deformation die to deform said length of metal while a portion of said length of metal proximate said deformation die and said deformation die remain immersed in said cryogenic liquefied gas.   
   
   
       10 . A method of strain hardening as recited in  claim 9 , wherein said cryogenic liquefied gas is liquid nitrogen. 
   
   
       11 . A method of strain hardening as recited in  claim 9  wherein said length of metal is a wire and said deformation die is a diameter reducing die. 
   
   
       12 . A method of strain hardening as recited in  claim 11 , wherein said wire is fed from a payoff reel, through said diameter reducing die, and onto a draw reel. 
   
   
       13 . A method of strain hardening as recited in  claim 12 , wherein said payoff reel is contained within said vessel and said draw reel is located outside said vessel. 
   
   
       14 . A method of strain hardening as recited in  claim 12 , wherein both said payoff reel and said draw reel are located outside said vessel. 
   
   
       15 . A method of strain hardening as recited in  claim 14 , wherein said wire is fed from said payoff reel to a first idler pulley, then through said diameter reducing die, then to a second idler pulley, and then to said draw reel. 
   
   
       16 . A method of strain hardening as recited in  claim 15 , wherein said first and second idler pulleys are contained within said vessel. 
   
   
       17 . A method of strain hardening as recited in  claim 3 , wherein said cryogenic liquefied gas is liquid nitrogen. 
   
   
       18 . A method of strain hardening as recited in  claim 4 , wherein said cryogenic liquefied gas is liquid nitrogen. 
   
   
       19 . A method of strain hardening as recited in  claim 11 , wherein said cryogenic liquefied gas is liquid nitrogen. 
   
   
       20 . A method of strain hardening as recited in  claim 12 , wherein said cryogenic liquefied gas is liquid nitrogen.