Bulk solidifying amorphous alloys with improved mechanical properties

• US 20060157164A1
• Filed: 12/16/2005
• Published: 07/20/2006
• Est. Priority Date: 12/20/2002
• Status: Active Grant

• Current Assignee: Crucible Intellectual Property LLC
• Original Assignee: Crucible Intellectual Property LLC
• Inventors: Johnson, William, Schroers, Jan
• Granted Patent: US 7,896,982 B2
• Time in Patent Office: Days
• US Class Current: 148/403
• CPC Class Codes: C22C 45/003 with one or more of the noble metals as major constituent

Abstract

Bulk solidifying amorphous alloys exhibiting improved processing and mechanical properties and methods of forming these alloys are provided. The bulk solidifying amorphous alloys are composed to have high Poisson'"'"'s ratio values. Exemplary Pt-based bulk solidifying amorphous alloys having such high Poisson'"'"'s ratio values are also described. The Pt-based alloys are based on Pt—Ni—Co—Cu—P alloys, and the mechanical properties of one exemplary alloy having a composition of substantially Pt_57.5Cu_14.7Ni_5.3P_22.5 are also described.

Claims

1. A bulk-solidifying amorphous alloy comprising:

at least four elemental components, wherein the combination of components has a Poisson'"'"'s ratio of at least 0.38, the alloy exhibiting an elastic strain limit of at least 1.5%, a ductility of more than 10% under compression geometries with aspect ratio more than 2, a bend ductility of more than 3% under bending geometries with a thickness more than 2.0 mm, and a fracture toughness greater than K1c>

35 MPa m<sup>−

1/2</sup>.

2. The bulk solidifying amorphous alloy of claim 1, wherein the bulk-solidifying amorphous alloy has an elastic strain limit in the range of 1.5% to 2.0%.

3. The bulk solidifying amorphous alloy of claim 1, wherein the bulk-solidifying amorphous alloy has a Poisson'"'"'s ratio of 0.42 or higher.

4. The bulk solidifying amorphous alloy of claim 3, wherein the bulk-solidifying amorphous alloy exhibits a ductility of more than 20% under compression geometries with aspect ratio more than 2.

5. The bulk solidifying amorphous alloy of claim 3, wherein the bulk-solidifying amorphous alloy exhibits a bend ductility of more than 3% under bending geometries with thickness more than 4.0 mm.

6. The bulk solidifying amorphous alloy of claim 3, wherein the bulk-solidifying amorphous alloy exhibits a bend ductility of more than 10% under bending geometries with thickness of more than 2.0 mm.

7. The bulk solidifying amorphous alloy of claim 3, wherein the bulk solidifying amorphous alloy has a Poisson'"'"'s ratio of 0.42 or higher and show a fracture toughness of K1c>

60 MPa m<sup>−

1/2</sup>.

8. The bulk solidifying amorphous alloy of claim 1, wherein the bulk-solidifying amorphous alloy has a crystalline volume fraction of less than 5% by volume.

9. The bulk solidifying amorphous alloy of claim 1, wherein the bulk-solidifying amorphous alloy is formed in a composite consisting of at least 10% of the bulk solidifying amorphous alloy.

10. The bulk solidifying amorphous alloy of claim 1, wherein the alloy is Pt-based.

11. The bulk solidifying amorphous alloy of claim 1, wherein the alloy is based on Pt—

Co—

Ni—

Cu—

P alloys.

12. The bulk solidifying amorphous alloy of claim 1, wherein the alloy is based on quarternary Pt—

Co—

Cu—

P alloys.

13. The bulk solidifying amorphous alloy of claim 1, wherein the bulk-solidifying amorphous alloy composition is Pt_57.5Cu_14.7Ni_5.3P_22.5.

14. The bulk solidifying amorphous alloy of claim 13, wherein, the bulk-solidifying has a high fracture toughness of more than 60 MPa m⁻

1/2.

15. The bulk solidifying amorphous alloy of claim 13, wherein the bulk-solidifying amorphous alloy has a plastic region of up to 20% under compressive loading with aspect ratios of greater than 2.

16. The bulk solidifying amorphous alloy of claim 13, wherein the bulk solidifying amorphous alloy has a fracture toughness of K1c>

70 MPa m<sup>−

1/2</sup>.

17. The bulk solidifying amorphous alloy of claim 13, wherein the bulk solidifying amorphous alloy is plastically deformable by more than 15% in an unconfined geometry under quasistatic compressive loading conditions.

18. The bulk solidifying amorphous alloy of claim 13, wherein the bulk solidifying amorphous alloy is plastically deformable under bending conditions by more than 2% for sample thicknesses up to 4 mm.

19. The bulk solidifying amorphous alloy of claim 13, wherein the bulk solidifying amorphous alloy has a critical crack radius of 4 mm.

20. The bulk solidifying amorphous alloy of claim 10, wherein the bulk-solidifying amorphous alloy exhibits a ductility of more than 10% under compression geometries with aspect ratio more than 2.

21. The bulk solidifying amorphous alloy of claim 10, wherein the bulk-solidifying amorphous alloy exhibits a ductility of more than 20% under compression geometries with aspect ratio more than 2.

22. The bulk solidifying amorphous alloy of claim 10, wherein the bulk-solidifying amorphous exhibits a bend ductility of more than 3% under bending geometries with thickness more than 2.0 mm.

23. The bulk solidifying amorphous alloy of claim 10, wherein the bulk-solidifying amorphous alloy exhibits a bend ductility of more than 3% under bending geometries with thickness more than 4.0 mm.

24. The bulk solidifying amorphous alloy of claim 10, wherein the bulk solidifying amorphous alloy exhibits a bend ductility of more than 10% under bending geometries with thickness of more than 2.0 mm.

25. The bulk solidifying amorphous alloy of claim 10, wherein the bulk solidifying amorphous alloy can be permanently plastically deformed at room temperature for sample sizes up to 4 mm×

4 mm in a bend test.

26. A method of forming a three-dimensional object having minimum dimensions of at least 0.5 mm in all dimensions and at least 50% amorphous phase by volume from the alloy as described in claim 1, comprising:

providing a molten volume of the alloy;

quenching the entire volume of the alloy from above its melting temperature to a temperature below its glass transition temperature to form an as-cast object, wherein the quenching occurs at a sufficient rate to prevent the formation of more than a 50% crystalline phase by volume.

27. The method of claim 26, further comprising reheating the as-cast alloy in a supercooled region after quenching and then re-quenching the alloy from above supercooled region to a temperature below its glass transition temperature at a sufficient rate to prevent the formation of more than a 5% crystalline phase.

28. The method of claim 27, wherein after the step of reheating the Poisson'"'"'s ratio for the as-cast and reheated alloy does not differ by more than 5%.

29. The method of claim 28, wherein the Poisson'"'"'s ratio of the alloy after reheating is at least 0.38.

30. The method of claim 29, wherein the step of quenching comprises cooling the bulk solidifying amorphous alloy at a rate substantially faster than the critical cooling rate of the alloy.

31. The method of claim 27 wherein, the bulk-solidifying amorphous alloy is Pt_57.5Cu_14.7Ni_5.3P_{22 5}, and the alloy is reheated in the supercooled liquid region for a time and temperature such that the crystalline phase of the alloy by volume is less than 3%, and the fracture toughness after this process is more than 60 NPa m⁻

1/2.

32. The method of claim 27, further comprising:

providing two or more pieces of the bulk-solidifying amorphous alloy; and

bonding said pieces together by applying pressure that results in the physical contact of the pieces during the reheating step.

33. The method of claim 26, wherein the three-dimensional object has minimum dimensions of at least 1.0 mm in all dimensions

34. The method of claim 26, further comprising forming the alloy at a temperature between the glass transition temperature and the crystallization temperature of the alloy to obtain a near net shape object.

35. The method of claim 26, further comprising:

providing a quantity of feedstock materials for the alloy; and

melting the feedstock under vacuum to form the molten alloy such that no flotation of bubbles can be observed.

36. The method of claim 26, wherein the molten alloy is processed under vacuum.

37. The method of claim 27, wherein after reheating the molten alloy is put under vacuum until no bubble flotation can be observed.

38. The method of claim 27, wherein the post-quenching reheating is conducted under vacuum until no bubble flotation can be observed.

39. The method of claim 35, wherein after melting under vacuum the pressure is increased from 5 to 150 psi.