Aluminum alloys, aluminum alloy products and methods for making the same

• US 20100183869A1
• Filed: 01/12/2010
• Published: 07/22/2010
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: Alcoa USA Corp. (Alcoa Corp.)
• Original Assignee: Alcoa Incorporated (Howmet Aerospace, Inc.)
• Inventors: Fields, James R., Abbott, Janell Lyn, Yan, Xinyan, Sullivan, Shawn Patrick, Askin, Albert L., Sawtell, Ralph R., Lin, Jen C.
• Granted Patent: US 8,349,462 B2
• Time in Patent Office: Days
• US Class Current: 428/332
• CPC Class Codes: B22D 17/00 Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
• CPC Class Codes: B22D 17/20 Accessories: Details
• CPC Class Codes: B22D 21/007 with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
• CPC Class Codes: B22D 25/00 Special casting characterised by the nature of the product B22D15/02, B22D17/16, B22D19/00 take precedence; casting stereotype plates B41D3/00
• CPC Class Codes: C22C 21/00 Alloys based on aluminium
• CPC Class Codes: C25D 11/022 Anodisation on selected surface areas
• CPC Class Codes: C25D 11/04 of aluminium or alloys based thereon
• CPC Class Codes: C25D 11/16 Pretreatment , e.g. desmutting
• CPC Class Codes: C25D 11/18 After-treatment, e.g. pore-sealing
• CPC Class Codes: C25D 5/02 Electroplating of selected surface areas
• CPC Class Codes: C25D 9/06 by anodic processes
• CPC Class Codes: Y10T 428/12736 Al-base component
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension

Abstract

Decorative shape cast products and methods, systems, compositions and apparatus for producing the same are described. In one embodiment, the decorative shape cast products are produced from an Al—Ni or Al—Ni—Mn alloy, with a tailored microstructure to facilitate production of anodized decorative shape cast product having the appropriate finish and mechanical properties.

Claims

1. An aluminum casting alloy consisting essentially of:

about 6.6 to about 8.0 wt. % Ni;

about 0.5 to about 3.5 wt. % Mn;

up to about 0.25 wt. % of any of Fe and Si;

up to about 0.5 wt. % of any of Cu, Zn, and Mg;

up to about 0.2 wt. % of any of Ti, Zr, and Sc, wherein one of B and C may be included up to about 0.1 wt. %;

up to about 0.05 wt. % of other elements, wherein the total of the other elements does not exceed 0.15 wt. %; and

the balance being aluminum.

2. An shape cast and anodized product produced from the aluminum alloy of claim 1, wherein the shape cast product has an ISO brightness of at least about 20.

3. The shape cast and anodized product of claim 2, wherein the shape cast product has a CIELAB L-value of at least about 55.

4. The shape cast and anodized product of claim 2, wherein the shape cast product realizes a tensile yield strength of at least about 100 MPa in the F temper.

5. The shape cast and anodized product of claim 2, wherein the shape cast product realizes an impact strength of at least about 4 joules in the F temper.

6. The shape cast and anodized product of claim 2, wherein the product has a layered microstructure;

wherein the layered microstructure comprises an outer layer and a second layer;

wherein the outer layer comprises alpha aluminum phase and eutectic microstructure;

wherein the outer layer comprises a thickness of not greater than about 400 microns.

7. A method comprising:

(a) selecting a product application for a shape cast aluminum alloy product;

(b) selecting a finishing style for the shape cast aluminum alloy product;

(c) selecting, based on at least one of steps (a) and (b);

(i) a predetermined microstructure of the shape cast aluminum alloy product; and

(ii) an alloy for use in producing the shape cast aluminum alloy product, wherein the alloy is one of;

(A) an Al—

Ni casting alloy comprising from about 0.5 wt. % to about 8.0 wt. Ni; and

(B) an Al—

Ni—

Mn casting alloy comprising from about 0.5 wt. % to about 8.0 wt. % Ni and from about 0.5 wt. % to about 3.5 wt. % Mn; and

(d) producing the shape cast product in response to the selection step (c), wherein the producing comprises;

(i) die casting the a shape cast product from either the Al—

Ni or the Al—

Ni—

Mn alloy; and

(ii) anodizing the shape cast aluminum alloy product, wherein the anodizing comprises forming a uniform oxide layer from a portion of the shape cast aluminum alloy product;

wherein after the anodizing step (ii), the shape cast aluminum alloy product realizes both (A) a CIELAB L-value of at least about 55 and (B) an ISO brightness of at least about 20.

8. The method of claim 7, wherein after the anodizing step (ii), the shape cast aluminum alloy product realizes a Delta-E of not greater than about 5.0.

9. The method of claim 7, wherein the finishing style includes a visually apparent surface defect free surface, and wherein the selecting step (c) comprises:

selecting a layered microstructure, wherein the layered microstructure comprises an outer layer having alpha aluminum phase and eutectic microstructure; and

wherein the producing step (d) comprises;

producing the shape cast product having the layered microstructure, wherein the outer layer has a thickness of not greater than about 400 microns; and

removing at least a portion of the outer layer from the shape cast product.

10. The method of claim 9, wherein the selecting step (c) comprises selecting a hypereutectic alloy composition.

11. The method of claim 10, wherein the alloy is the Al—

Ni—

Mn alloy.

12. The method of claim 10, wherein the uniform oxide layer is associated with an intended viewing surface of the product, wherein the method comprises:

applying a colorant to at least a portion of the uniform oxide layer, wherein after the applying step, the intended viewing surface of the shape cast product has a Delta-E of not greater than about 5.0 due to, at least in part, the uniformity of the oxide layer, and wherein the intended viewing surface is substantially free of visually apparent surface defects.

13. The method of claim 7, wherein the finishing style is a marbled surface, and wherein the selecting step (c) comprises:

selecting a layered microstructure, wherein the layered microstructure comprises an outer layer having a fairly regular distribution of alpha aluminum phase and eutectic microstructure; and

wherein the producing step (d) comprises;

producing the shape cast product having the layered microstructure; and

applying a colorant to the uniform oxide layer of the layered microstructure, wherein, after the applying step, the shape cast product has a marbled intended viewing surface due to, at least in part, the selected alpha aluminum phase and eutectic microstructure.

14. The method of claim 13, wherein the selecting step (c) comprises selecting a hypoeutectic alloy composition.

15. The method of claim 14, wherein the alloy is an Al—

Ni—

Mn alloy.

38. The thin-walled shape cast aluminum alloy product of claim 7, wherein the coating passes a cross-hatching test in accordance with ASTM D3359-09, wherein the intended viewing surface of the thin walled shape cast aluminum alloy product contains no pits on the intended viewing surface after 2 hours of exposure to a salt solution when tested in accordance with ASTM B117, wherein the coating passes a Taber abrasion test in accordance with ASTM D4060-07, wherein the coating of the thin walled shape cast aluminum alloy product realizes a Delta-E of less than about 0.7 after 24 hours of exposure to a QUV-A bulb having a wavelength of 340 nm when tested in accordance with ISO 11507, wherein the intended viewing surface realizes no material visual change following exposure to artificial sweat when tested in accordance with EN 1811 to nickel extraction, wherein the intended viewing surface of the decorative shape cast product achieves a rating of at least about 2H as measured in accordance with the pencil hardness test of ASTM D3363-09, and wherein the variability of the color of the intended viewing surface of the shape cast product is not greater than +/−

5.0 Delta E.

16. A method comprising:

(a) flowing a molten metal in an initial path;

(b) forcing the molten metal into a casting cavity from the initial path at an angle in the range of from about 30 degrees to about 90 degrees, wherein the casting cavity is in fluid communication with the initial path;

(c) cooling the molten metal in the casting cavity to produce a solidified metal; and

(d) producing an aluminum product having an intended viewing surface from the solidified metal and a nominal wall thickness of not greater than about 2.0 mm, wherein the producing step comprises anodizing the aluminum product, wherein, after the anodizing, the intended viewing surface of aluminum product is substantially free of visually apparent surface defects.

17. The method of claim 16, wherein the aluminum product has a nominal wall thickness of not greater than about 1.0 mm.

18. The method of claim 16, wherein the distance traveled by the molten metal from the initial path into the casting cavity is not greater than about 15 mm.

19. The method of claim 18, wherein the distance traveled by the molten metal from the initial path into the casting cavity is not greater than about 10 mm.

20. The method of claim 19, wherein the distance traveled by the molten metal from the initial path into the casting cavity is not greater than about 5 mm.

21. The method of claim 16, wherein the initial path comprises a runner passageway.

22. The method of claim 16, wherein the initial path is connected to the casting cavity via a transition path.

23. The method of claim 22, wherein the transition path includes a tangential gate, and wherein, after the anodizing, the intended viewing surface of the aluminum product is substantially free of visually apparent surface defects due to, at least in part, the tangential gate.

24. The method of claim 23, wherein the forcing step comprises forcing the molten metal into a casting cavity from the initial path at an angle in the range of 60 to 90 degrees.

25. The method of claim 23, wherein the forcing step comprises forcing the molten metal into a casting cavity from the initial path at an angle in the range of 70 to 90 degrees.

26. The method of claim 23, wherein the forcing step comprises forcing the molten metal into a casting cavity from the initial path at an angle in the range of 80 to 90 degrees.

27. A method comprising:

(a) flowing a molten metal in an initial path;

(b) forcing the molten metal into a casting cavity from the initial path at an angle in the range of from about 0 degrees to about 90 degrees, wherein the casting cavity is in fluid communication with the initial path, and wherein the distance traveled by the molten metal from the initial path into the casting cavity is not greater than about 15 mm;

(c) cooling the molten metal in the casting cavity to produce a solidified metal; and

(d) producing an aluminum product having an intended viewing surface from the solidified metal and a nominal wall thickness of not greater than about 2.0 mm, wherein the producing step comprises anodizing the aluminum product, wherein, after the anodizing, the intended viewing surface of aluminum product is substantially free of visually apparent surface defects.

28. The method of claim 27, wherein the aluminum product has a nominal wall thickness of not greater than about 1.0 mm.

29. The method of claim 28, wherein the distance traveled by the molten metal from the initial path into the casting cavity is not greater than about 5 mm.

30. The method of claim 29, wherein the forcing step comprises forcing the molten metal into a casting cavity from the initial path at an angle in the range of 80 to 90 degrees.

31. A thin-walled shape cast aluminum alloy product comprising:

a body comprising an intended viewing surface, wherein the body comprises;

(I) an aluminum alloy base, wherein the aluminum alloy base comprises from about 0.5 to about 8.0 wt. % Ni and up to about 3.5 wt. % Mn;

(II) a uniform oxide layer formed from the aluminum alloy base, wherein the oxide layer comprises a plurality of pores, and wherein the oxide layer is associated with the intended viewing surface of the thin-walled shape cast aluminum alloy product;

wherein the intended viewing surface of the shape cast product is substantially free of visually apparent surface defects; and

wherein the thin-walled shape cast aluminum alloy product has a tensile yield strength of at least about 100 MPa in the F temper.

32. The thin-walled shape cast aluminum alloy product of claim 31, wherein the oxide layer consists essentially of Al, Ni, O and at least one of S, P, Cr, and B.

33. The thin-walled shape cast aluminum alloy product of claim 31, wherein the oxide layer consists essentially of Al, Ni, O and at least one of S and P.

34. The thin-walled shape cast aluminum alloy product of claim 31, wherein the body is free of non-oxide layers between the aluminum alloy base and the oxide layer.

35. The thin-walled shape cast aluminum alloy product of claim 31, wherein the variability of the color of the intended viewing surface of the shape cast product is not greater than +/−

5.0 Delta E, and wherein the variability is due to, at least in part, the uniformity of the uniform oxide layer.

36. The thin-walled shape cast aluminum alloy product of claim 31, comprising:

a colorant at least partially filling the pores of the oxide layer.

37. The thin-walled shape cast aluminum alloy product of claim 36, wherein the colorant is in the form of a silicon polymer coating, wherein the coating overlays at least a portion of the oxide layer.

39. The thin-walled shape cast aluminum alloy product of claim 36, wherein the variability of the color of the intended viewing surface of the shape cast product is not greater than +/−

5.0 Delta E.

40. The thin-walled shape cast aluminum alloy product of claim 31, wherein the aluminum alloy composition comprises a hypereutectic alloy composition of aluminum, nickel and manganese.

41. A thin-walled cast aluminum alloy product comprising:

a body comprising an intended viewing surface, wherein the body comprises;

(I) an aluminum alloy base having a layered microstructure, wherein the aluminum alloy base comprises from about 0.5 to about 8.0 wt. % Ni and up to about 3.5 wt. % Mn, and wherein the layered microstructure comprises a fairly regular distribution of alpha aluminum phase and eutectic microstructure;

(II) an oxide layer formed of the aluminum alloy base, wherein the oxide layer comprises a plurality of pores, wherein the oxide layer is associated with the intended viewing surface of the thin-walled shape cast aluminum alloy product, and wherein a colorant at least partially fills the pores of the oxide layer;

wherein the intended viewing surface of the shape cast product has a substantially marbled appearance, wherein the alpha aluminum phase comprises a first color due to the colorant, and wherein the eutectic microstructure comprises a second color due to the colorant, wherein the second color is different than the first color, wherein the combination of the first color of the alpha aluminum phase and the second color of the eutectic microstructure at least partially contributes to the marbled appearance.

42. A method comprising:

(a) producing a thin walled shape cast aluminum alloy product having an intended viewing surface;

(i) wherein the producing comprises die casting an aluminum alloy containing from about 0.5 to about 8.0 wt. % Ni and up to about 3.5 wt. % Mn;

(ii) wherein, after the producing step, the thin-walled shape cast product comprises an outer layer having alpha aluminum phase and eutectic phase;

(b) removing not greater than about 500 microns of the outer layer from the thin-walled shape cast product;

(c) anodizing the thin-walled shape cast product, wherein the anodizing comprises forming an oxide layer from a portion of the thin walled shape cast aluminum alloy product, wherein the oxide layer is associated with the intended viewing surface, and wherein the oxide layer comprises a plurality of pores;

(d) applying a colorant to the oxide layer of the thin walled shape cast aluminum alloy product, wherein after the applying step at least some of the colorant is at least partially disposed within the pores of the oxide layer;

wherein, after the applying step, the intended viewing surface is substantially free of visually apparent surface defects; and

wherein, after the applying step, the variability of the color of the intended viewing surface is not greater than +/−

5.0 Delta E.

43. The method of claim 42, wherein the applying colorant step comprises:

contacting the oxide layer with a dye and in the absence of electric current;

44. The method of claim 42, wherein the applying step comprises:

depositing a coating precursor on a surface of the oxide layer; and

converting the coating precursor to a coating, wherein after the converting step the coating substantially covers the oxide layer.

45. The method of claim 44, wherein the coating precursor is a precursor to a silicon polymer and wherein the covering step comprises applying radiation or heat to the coating precursor to produce a coating containing the silicon polymer.

46. A method comprising:

(a) producing a thin walled shape cast aluminum alloy product having an intended viewing surface;

(i) wherein the producing comprises die casting an aluminum alloy containing from about 0.5 to about 8.0 wt. % Ni and up to about 3.5 wt. % Mn;

(ii) wherein, after the producing step, the thin-walled shape cast product comprises a fairly regular distribution of alpha aluminum phase and eutectic phase;

(b) removing not greater than about 500 microns of the outer layer from the thin-walled shape cast product;

(c) anodizing the thin-walled shape cast product, wherein the anodizing comprises forming an oxide layer from a portion of the thin walled shape cast aluminum alloy product, wherein the oxide layer is associated with the intended viewing surface, and wherein the oxide layer comprises a plurality of pores;

(d) applying a colorant to the oxide layer of the thin walled shape cast aluminum alloy product, wherein after the applying step at least some of the colorant is at least partially disposed within the pores of the oxide layer;

wherein, after the applying step, the intended viewing surface of the shape cast product has a substantially marbled appearance, wherein the alpha aluminum phase comprises a first color due to the colorant, and wherein the eutectic microstructure comprises a second color due to the colorant, wherein the second color is different than the first color, wherein the combination of the first color of the alpha aluminum phase and the second color of the eutectic microstructure at least partially contributes to the marbled appearance.