High performance nanostructured materials and methods of making the same

Abstract

In accordance with the invention, nanostructured metallic materials having high tensile strength and increased ductility are prepared by providing a metallic material, deforming the metallic material to form a plurality of dislocation cell structures, annealing the material at a temperature from about 0.3 to about 0.7 of its absolute melting temperature, and cooling the annealed metallic material. The result is a nanostructured metal or alloy having increased tensile strength as compared with the corresponding coarse-grained material and substantially greater ductility as compared with nanostructured material made by conventional processes. Using this process applicants have made nanostructured alloys with tensile strengths in excess of 1.5 Gpa and ductility greater than 1 per cent strain-to-failure. They have also made nanostructured metals with tensile strength in excess of 400 MPa and ductility in excess of 50% strain-to-failure. The new materials are useful in a variety of applications such as rotors, electric generators, magnetic bearings, microelectromechanical devices and biomedical systems.

What is claimed:  
     
         1 . A method of making a nanostructured metallic material comprising the steps of: 
 providing a metallic material;    deforming the metallic material wherein a plurality of dislocation cell structures are formed;    annealing the metallic material at a temperature from about 0.3 to about 0.7 of its absolute melting temperature; and    cooling said metallic material to produce nanostructured material.    
     
     
         2 . The method of  claim 1 , wherein said temperature is from about 0.37-0.53 of its absolute melting temperature.  
     
     
         3 . The method of  claim 1 , wherein said temperature is from about 0.39 to about 0.44 of its absolute melting temperature.  
     
     
         4 . The method of  claim 1 , wherein said temperature is at least about 350 degrees Celsius.  
     
     
         5 . A method of adjusting the tensile strength of a nanostructured material comprising: 
 providing a metallic material;    deforming the metallic material wherein a plurality of dislocation cell structures are formed;    annealing the metallic material at a temperature from about 0.30 to 0.70 of its absolute melting temperature for a time from about 1000 hours to several seconds; and    cooling the metallic material.    
     
     
         6 . A method of adjusting the ductility of a nanostructured crystalline material comprising the steps of: 
 providing a metallic material;    deforming said metallic material so that a plurality of dislocation cell structures are formed;    annealing said metallic material at a temperature from about 0.37 to 0.53 of its absolute melting temperature for a period of time from 50 hours to several minutes; and    cooling said metallic material after said annealing step.    
     
     
         7 . A method of adjusting the ductility of a nanostructured crystalline material comprising the steps of: 
 providing a metallic material;    deforming said metallic material so that a plurality of dislocation cell structures are formed;    annealing said metallic material at a temperature from about 0.39 to about 0.44 of its absolute melting temperature for a period of time from about 20 hours to about 1 hour, wherein the temperature and time are selected to achieve a ductility of at least about 1% plastic strain-to-failure and a tensile elastic yield strain of at least about 0.5%; and    cooling said metallic material after said annealing step.    
     
     
         8 . The method of  claim 5  wherein said deforming step further comprises cold rolling said metallic material with a thickness reduction ratio in the range from about 50% to about 95%.  
     
     
         9 . The method of  claim 8  wherein said thickness reduction ratio is at least about 90%.  
     
     
         10 . The method of  claim 8  wherein said thickness reduction ratio is at least about 80%.  
     
     
         11 . A nanostructured metallic material having a tensile yield strength of at least about 1.5 GPa and a ductility of at least about 1 percent strain-to-failure.  
     
     
         12 . The nanostructured material of  claim 11 , further comprising microstructures with an average grain size ranging from about 10 nanometers to about 900 nanometers.  
     
     
         13 . The nanostructured material of  claim 11 , further comprising microstructures with an average grain size of at least 10 nanometers.  
     
     
         14 . The nanostructured material of  claim 11  having a tensile elastic yield strain of at least about 0.5% and a ductility from about 1 to about 18 percent plastic strain-to-failure.  
     
     
         15 . The nanostructured material of  claim 11 , wherein said ductility is from between 1.3 to about 5.5 percent plastic strain-to-failure.  
     
     
         16 . The nanostructured material of  claim 11 , wherein said the nanostructured material has a Vicker's hardness of about 5.5 to about 10 GPa.  
     
     
         17 . Nanostructured magnetic materials, wherein the materials are cold-rolled and annealed at a temperature ranging from about 350 to about 705 degrees Celsius, have a room temperature yield strength in excess of about 1.2 GPa and tensile ductility in excess of about 1% plastic strain-to-failure.  
     
     
         18 . The nanostructured magnetic materials of  claim 17 , wherein the materials consist essentially of about 0.003% to about 0.02% C, no more than about 0.10% Mn, no more than about 0.10% Si, no more than about 0.01% P, no more than about 0.003% S, no more than about 0.1% Cr, no more than about 0.2% Ni, no more than about 0.1% Mo, from about 48 to about 50% Co, from about 1.8 to about 2.2% V, from about 0.03 to about 0.5% Nb, no more than about 0.004% N, and no more than 0.006% O, and iron as the balance.  
     
     
         19 . The nanostructured magnetic materials of  claim 17 , wherein said materials consist essentially of 48.78% cobalt, 1.92% vanadium, 0.06% niobium, 0.012% carbon, 0.1% nickel, balanced with iron.  
     
     
         20 . A nanostructured metallic material having a tensile yield strength of at least about 400 MPa and a ductility of at least about 5 percent strain-to-failure.  
     
     
         21 . The nanostructured material of  claim 20  wherein the ductility is at least 30 percent strain-to-failure.  
     
     
         22 . The nanostructured material of  claim 20  wherein the metal comprises copper.  
     
     
         23 . The nanostructured material of  claim 20  wherein the metal consists essentially of copper.  
     
     
         24 . The nanostructured material of  claim 20  wherein the nanostructured metal has a strength in excess of 3 times the strength of the conventional coarse-grained metal and a ductility in excess of 50 percent strain-to-failure.  
     
     
         25 . The method of  claim 1  wherein the nanostructured metallic material is metal and the deformation comprises cold working the metal.  
     
     
         26 . The method of  claim 25  wherein the metal is cold worked at liquid nitrogen temperature.  
     
     
         27 . The method of  claim 25  wherein the cold worked metal is heat treated to recrystallization and secondary recrystallization.