ALUMINUM ALLOY AND METHODS FOR ADDITIVE MANUFACTURING OF LIGHTWEIGHT PARTS

Abstract

An aluminum (Al) alloy consisting of titanium (Ti) with a proportion of 0.1 wt % to 15 wt %; scandium (Sc) with a proportion of 0.1 wt % to 3.0 wt %; zirconium (Zr) with a proportion of 0.1 wt % to 3.0 wt %; manganese (Mn) with a proportion of 0.1 wt % to 3.0 wt %; and a balance Al and unavoidable impurities with a total of less than 0.5 wt %. The alloy is used in an additive manufacturing method for manufacturing high strength, high ductile lightweight parts for aircraft. The alloy may be initially produced as a powder that is remelted during the manufacturing process.

Claims

1.-15. (canceled)

16. An aluminum (Al) alloy consisting of: 0.1 wt % to 15 wt % titanium (Ti); 0.1 wt % to 3.0 wt % scandium (Sc); 0.1 wt % to 3.0 wt % zirconium (Zr); 0.1 wt % to 10.0 wt % manganese (Mn); less than 0.5 wt % unavoidable impurities; and, balance Al, optionally at least one first additional alloy element selected from a group consisting of: tantalum (Ta), hafnium (Hf), Yttrium (Y), and erbium (Er), wherein an individual proportion of an individual first additional alloy element does not exceed 2.0 wt % and a total proportion of all first additional alloy elements does not exceed 3.0 wt %; optionally at least one second additional alloy element selected from a group consisting of: vanadium (V), niobium (Nb), chromium (Cr), molybdenum (Mo), silicon (Si), iron (Fe), and cobalt (Co), wherein an individual proportion of each second additional alloy element does not exceed 3.0 wt %, and a total proportion of all second additional alloy elements does not exceed 3.0 wt %; and, optionally at least one third additional alloy element selected from a group consisting of: magnesium (Mg) and calcium (Ca), wherein an individual proportion of each third additional alloy element is less than 2.0 wt %, and a total proportion of all third additional alloy elements does not exceed 3.0 wt %.

17. The aluminum alloy according to claim 16, wherein Mn has a proportion of 0.1 wt % to 6 wt %.

18. The aluminum alloy according to claim 16, wherein Ti has a proportion of 0.5 wt % to 5.0 wt %, Sc has a proportion from 0.2 wt % to 1.5 wt %, and Zr has a proportion of 0.20 wt % to 0.70 wt %.

19. The aluminum alloy according to claim 18, wherein Ti has a proportion of 1.0 wt % to 5.0 wt %, Sc has a proportion of 0.5 wt % to 1.0 wt %, and Zr with a proportion of 0.2 wt % to 0.8 wt %.

20. The aluminum alloy according to claim 16, wherein Ti has a proportion of 1.0 wt % to 5.0 wt %, Sc has a proportion of 0.6 wt % to 1.1 wt %, and Zr has a proportion of 0.20 wt % to 0.50 wt %.

21. The aluminum alloy according to claim 16, wherein Ti has a proportion of up to 2.0 wt %, and the alloy consists only of Al, Mn, and metals that have an enthalpy of vaporization that is greater than that of Al or that have a smaller vapor pressure than that of Al.

22. The aluminum alloy according to claim 16, wherein Ti has a proportion of more than 2.0 wt % to 5.0 wt %, and Mn has a proportion of 0.1 wt % to 2.0 wt %.

23. The aluminum alloy according to claim 16, consisting only of Al, Mn, and metals that have an enthalpy of vaporization that is greater than that of Al or that have a smaller vapor pressure than that of Al.

24. The aluminum alloy according to claim 16, wherein the alloy is free of magnesium (Mg), or calcium (Ca), or nickel (Ni), or any combination thereof.

25. A method for additive manufacturing of a lightweight part precursor from the aluminum alloy according to claim 16, the method comprising: a) melting the metals into an aluminum alloy melt; b) cooling the aluminum alloy melt or letting the aluminum alloy melt cool b1) in a solidification process having a cooling speed of 1,000 K/s to K/s, and obtaining a solidified, when applicable, powdery aluminum alloy with scandium included in solid solution; or b2) in a cooling process and obtaining a solidified aluminum alloy; and, c) crushing the aluminum alloy of step b1) or b2) into a powder.

26. The method of claim 25 further comprising: d) manufacturing a powder bed from the powder obtained in step c); and, e) additive manufacturing of a three-dimensional part precursor in a laser melting process in the powder bed with a laser by locally melting the powder and cooling or letting cool a locally melted portion and obtaining the three-dimensional part precursor.

27. The method of claim 26, further comprising: heat treating the three-dimensional part precursor oat a temperature that hardens the three-dimensional part precursor due to precipitation hardening.

28. A part obtained by the method according to claim 27.

29. A part precursor obtained by the method according to claim 26.

30. The method of claim 25, wherein the solidification process of step b1 comprises melt spinning, powder atomizing with gas or in water, thin strip casting or spray compacting, and obtaining a solidified and, when applicable, powdery aluminum alloy with scandium included in solid solution.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] Embodiments of the invention are now described in more detail.

[0063] A) Process for the Production of Aluminum Alloys

Example 1 Production of Powdered Aluminum Alloys

[0064] In an inert crucible, 0.75 wt % Sc, 0.35 wt % Zr, 1.0 wt % Ti, 1.0 wt % Mn and 96.9 wt % Al are melted. The melt can be homogenized before further processing.

[0065] An initial portion of the melt is poured into an inert crucible where it cools and solidifies. During cooling, primary Al3Sc, Al3Zr and Al3Ti phases precipitate. The resulting material is crushed into a powder that can be used for selective laser melting in a powder bed.

[0066] A second portion of the melt is poured onto a rotating copper roll cooled with water in a melt spinning process. The melt cools at a rate of 1,000,000 K/s forming a strip. The melt cools so rapidly that the formation of Al3Sc, Al3Zr and Al3Ti is completely or substantially suppressed. The ribbon is cut into short flakes.

[0067] The alloy material obtained from the two cooling processes is reduced to a powder that can be used for selective laser melting in a powder bed.

Example 2 Production of Powdered Aluminum Alloys with Different Titanium Content

[0068] The above process is repeated with the proportion of Ti increased to 3.0 wt %, 5.0 wt %, 10.0 wt % and 15.0 wt % and the proportion of Al decreased accordingly. The proportion of Sc, Zr and Mn remains unchanged.

Example 3 Production of a Powdered Aluminum Alloy with Vanadium Content

[0069] The process of Example 1 is repeated, with an additional 2.0 wt % of vanadium being added to the crucible and the content of Ti, Sc and Zr being kept constant.

Example 4 Production of a Powdered Aluminum Alloy with Nickel Content

[0070] The process of Example 1 is repeated with an additional 1.2 wt % nickel added to the crucible and the content of Ti, Sc and Zr kept constant.

Example 5 Production of Powdered Aluminum Alloy with Chromium-Vanadium Content

[0071] The process of Example 1 is repeated with an additional 1.0 wt % vanadium and 2.0 wt % chromium added to the crucible and the titanium content increased to 5 wt %. The Zr content remains unchanged.

Example 6 Production of Powdered Aluminum Alloy with Different Mn Content

[0072] The process according to Example 1 or 2 is repeated, whereby the proportion of Mn is changed to 0.1 wt %, 0.2 wt %, 0.3 wt, 0.4 wt %, 0.5 wt %, 1.5 wt %, 2.0 wt %, 2.5 wt %, 4 wt %, and 6 wt %, with the proportion of Al being adjusted accordingly.

[0073] B) Process for the Production of a Lightweight Precursor by the L-PBF Process.

[0074] In each case, an aluminum alloy powder from one of the above examples 1 to 6 is added to a system for additive manufacturing by selective laser melting, forming a powder bed. The laser beam is moved over the three-dimensional powder bed according to the digital information, whereby the powder bed is lowered step by step and new powder layers are applied. The cooling of the spot-melted aluminum alloy is so fast that scandium, zirconium and titanium are completely or essentially or predominantly frozen in solid solution, irrespective of the other composition of the aluminum alloy and irrespective of whether the powder has been produced by normal cooling or rapid cooling, for example at a rate of 1,000,000 K/sec. After completion of the scanning process, the aluminum alloy component precursor is removed from the powder bed.

[0075] C) Process for Producing a Lightweight Component

[0076] The component precursor produced in B) is heated to a temperature, such as in the range of 250 C. to 450 C., preferably 300 C. to 400 C. and even more preferably 325 C. to 350 C., at which precipitation of various Al3X phases (X=Ti, Zr, Sc or any non-stoichiometric mixture of the individual elements) occurs. Al3Ti is also precipitated, but compared to Al3Sc and Al3Zr, a predominant or larger proportion of the titanium remains in solid solution.

[0077] In summary, the invention relates to an aluminum (Al) alloy consisting of titanium (Ti) with a proportion of 0.1 wt % to 15 wt %; scandium (Sc) with a proportion of 0.1 wt % to 3.0 wt %; zirconium (Zr) with a proportion of 0.1 wt % to 3.0 wt %; manganese (Mn) with a proportion of 0.1 wt % to 3.0 wt %; and a balance Al and unavoidable impurities with a total of less than 0.5 wt %. The alloy is used in an additive manufacturing method for manufacturing high strength, high ductile lightweight parts for aircraft. The alloy may be initially produced as a powder that is remelted during the manufacturing process, whereby the desired features are achieved.

[0078] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, the terms a or one do not exclude a plural number, and the term or means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.