High performance nanostructured materials and methods of making the same

• US 6,596,101 B2
• Filed: 10/03/2001
• Issued: 07/22/2003
• Est. Priority Date: 10/05/2000
• Status: Expired due to Term

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Shang, Changhe, Chien, Chia-Ling, Cammarata, Robert, Weihs, Timothy P.
• Primary Examiner(s): Yee, Deborah
• Application Number:
  US09/970,402
• Publication Number:
  US 20020069944A1
• Time in Patent Office: 657 Days
• Field of Search: 148/120, 148/121, 148/122, 148/300, 148/320, 148/442, 148/538, 148/540, 148/545, 148/651, 420/127, 420/581
• US Class Current: 148/442
• CPC Class Codes: C21D 2201/03 Amorphous or microcrystalline structure
• CPC Class Codes: C21D 6/007 containing Co
• CPC Class Codes: C21D 8/1233 Cold rolling
• CPC Class Codes: C21D 8/1272 Final recrystallisation annealing
• CPC Class Codes: C22C 30/00 Alloys containing less than 50% by weight of each constituent
• CPC Class Codes: C22C 38/10 containing cobalt
• CPC Class Codes: C22C 38/12 containing tungsten, tantalum, molybdenum, vanadium, or niobium
• CPC Class Codes: C22F 1/00 Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working apparatus for mechanical working of metal B21, B23, B24
• CPC Class Codes: C22F 1/10 of nickel or cobalt or alloys based thereon
• CPC Class Codes: H01F 1/147 Alloys characterised by their composition treatment thereof for enhancing their electromagnetic properties C21D8/12
• CPC Class Codes: H01F 1/15316 based on Co H01F1/15325 takes precedence
• CPC Class Codes: H01F 1/15333 containing nanocrystallites, e.g. obtained by annealing

Abstract

Preferred embodiments of the invention provide new nanostructured materials and methods for preparing nanostructured materials having increased tensile strength and ductility, increased hardness, and very fine grain sizes making such materials useful for a variety of applications such as rotors, electric generators, magnetic bearings, aerospace and many other structural and nonstructural applications. The preferred nanostructured materials have a tensile yield strength from at least about 1.9 to about 2.3 GPa and a tensile ductility from at least 1%. Preferred embodiments of the invention also provide a method of making a nanostructured material comprising melting a metallic material, solidifying the material, deforming the material, forming a plurality of dislocation cell structures, annealing the deformed material at a temperature from about 0.30 to about 0.70 of its absolute melting temperature, and cooling the material.

Claims

1. A nanostructure material having a tensile yield strength from at least about 1.5 to about 2.3 GPa and a ductility of from at least about 1 to about 18 percent strain-to-failure,

wherein the material consists 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.

2. The nanostructured material of claim 1, further comprising microstructures with a grain size ranging from about 10 nanometers to about 900 nanometers.

3. The nanostructured material of claim 1, further comprising microstructures with a grain size of at least 10 nanometers.

5. The nanostructured material of claim 1, wherein said ductility is from between 1.3 to about 5.5 percent plastic strain-to-failure.

6. The nanostructured material of claim 1, wherein said the nanostructured material has a Vicker'"'"'s hardness from about 5.5 to about 10 GPa.

4. A nanostructured material having a tensile elastic yield strain of at least about 1% for the material and a ductility from at least about 1 to about 18 percent plastic strain-to-failure.

7. A method of making a nanostructured material comprising melting a metallic material into a liquid state, solidifying the material, deforming said metallic material wherein a plurality of dislocation cell structures are formed, annealing said 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 having a tensile elastic yield strain of at least about 1% for the material and a ductility of at least about 1 percent plastic strain-to-failure.

8. The method of claim 7, wherein said temperature is from about 0.37-0.53 of its absolute melting temperature.

9. The method of claim 7, wherein said temperature is from about 0.39 to about 0.44 of its absolute melting temperature.

10. The method of claim 7, wherein said temperature is at least about 350 degrees Celsius.

11. A method of adjusting the tensile strength of a nanostructured material comprising:

melting a metallic material into a liquid state;

solidifying said material;

deforming said metallic material wherein a plurality of dislocation cell structures are formed;

annealing said 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, wherein the temperature and time are selected to achieve a tensile elastic yield strain of at least about 1% for the material for said the nanostructured material; and

cooling said metallic material.

14. The method of claim 11 wherein said deforming step further comprises cold rolling said metallic material with a thickness reduction ratio from about 50% to about 95%.

15. The method of claim 14 herein said thickness reduction ratio is at least about 90%.

16. The method of claim 14 wherein said thickness reduction ratio is at least about 80%.

12. A method of adjusting the ductility of a nanostructured crystalline material comprising the steps of:

melting a metallic material into a liquid state;

solidifying said 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, wherein the temperature and time are selected to achieve a ductility from at least about 1% percent to about 18 percent plastic strain-to-failure; and

cooling said metallic material after said annealing step.

13. A method of adjusting the ductility of a nanostructured crystalline material comprising the steps of:

melting a metallic material into a liquid state;

solidifying said 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 from at least about 1% to about 18 percent plastic strain-to-failure; and

cooling said metallic material after said annealing step.

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 from 1.2 GPa to more than 2.3 GPa, and tensile ductility from 1% to more than 18% plastic strain-to-failure;

wherein the material consists 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.

18. 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 from 1.2 GPa to more than 2.3 GPa, and tensile ductility from 1% to more than 18% plastic strain-to-failure;

wherein said materials consist essentially of 48.78% cobalt, 1.92% vanadium, 0.06% niobium, 0.012% carbon, 0.1% nickel, balanced with iron.