NICKEL-IRON-ALUMINUM-CHROMIUM BASED ALLOYS, AND PRODUCTS MADE THEREFROM
The present disclosure relates to new nickel-iron-aluminum-chromium based alloys. Generally, the new alloys contain 20-40 at. % Ni, 15-40 at. % Fe, 5-20 at % Al, and 5-26 at. % Cr, the balance being optional incidental elements and unavoidable impurities. Generally, methods for producing the new alloys include one or more of heating a mixture above its liquidus temperature, then cooling the mixture below its solidus temperature, optionally hot and/or cold working the solid material into a final product form, then heating and quenching the solid material, and precipitation hardening the solid material.
1 . A method comprising:
(a) heating a mixture above its liquidus temperature, wherein the mixture comprises:
(i) 20-40 at. % Ni;
(ii) 15-40 at. % Fe;
(iii) 5-20 at % Al; and
(iv) 5-26 at. % Cr;
(b) cooling the mixture below its solidus temperature, thereby forming a solid material having a mixed fcc+bcc crystalline structure, wherein the mixture includes a sufficient amount of the Ni, the Fe, the Al and the Cr to realize the mixed fcc+bcc crystalline structure;
(c) optionally hot and/or cold working the solid material into a final product form;
(d) heating the solid material, thereby dissolving at least some second phase particles within the solid material;
(e) quenching the solid material; and
(f) precipitation hardening the solid material, thereby forming precipitates within the mixed fcc+bcc crystalline structure of the solid material.
2 . The method of claim 1 , wherein the mixture comprises 60-77 at. % Ni+Fe.
3 . The method of claim 2 , wherein the mixture comprises 23-40 at. % Al+Cr.
4 . The method of claim 3 , wherein the mixture includes 27.5-40 at. % Ni.
5 . The method of claim 4 , wherein the mixture includes 25-40 at. % Fe.
6 . The method of claim 5 , wherein the mixture includes at least 12 at. % Cr.
7 . The method of claim 6 , wherein the mixture includes not greater than 16 at. % Al.
8 . The method of claim 1 , wherein the balance of the solid material is optional incidental elements and unavoidable impurities, wherein the optional incidental elements comprise:
up to 15 at. %, in total, of one or more of cobalt (Co), copper (Cu), molybdenum (Mo), manganese (Mn), and tungsten (W);
up to 10 at. %, in total, of one or more of niobium (Nb), tantalum (Ta), and titanium (Ti);
up to 10 at. % carbon (C);
up to 5 at. % of silicon (Si);
up to 5 at. %, in total, of one or more of vanadium (V) and hafnium (Hf);
up to 2 at. %, in total, of one or more of boron (B) and zirconium (Zr);
up to 1 at. %, in total, of magnesium (Mg), calcium (Ca), cerium (Ce) and lanthanum (La);
up to 1 at. % of nitrogen (N); and
up to 10 vol. % of at least one ceramic material.
9 . The method of claim 8 , wherein the mixture includes at least 0.5 at. % Ti.
10 . The method of claim 9 , wherein a combined amount of Al plus Ti in the mixture is not greater than 20 at. %.
11 . The method of claim 1 , wherein the solid material comprises an alloy matrix and wherein the alloy matrix comprises at least 3.0 vol. % of fcc crystalline structures.
12 . The method of claim 11 , wherein the cooling the mixture below its solidus temperature step comprises first forming fcc crystalline structures from the mixture and then forming bcc crystalline structures.
13 . The method of claim 12 , wherein the solid material comprises dendritic fcc crystalline structures.
14 . The method of claim 1 , wherein the heating step (a) comprises selectively heating a portion of a powder comprising the mixture via a laser, thereby forming a molten pool having at least Ni, Fe, Al, and Cr therein; and
wherein the cooling step (b) comprises cooling the molten pool at a cooling rate of at least 1000° C. per second.
15 . The method of claim 1 , wherein step (c) is completed and the method includes hot and/or cold working the solid material into the final product form;
wherein the heating step (d) comprises heating the final product form, thereby dissolving at least some second phase particles within the final product form;
wherein the quenching step (e) comprises quenching the final product form; and
wherein the precipitating hardening step (f) comprises precipitation hardening the final product form, thereby forming precipitates within the mixed fcc+bcc crystalline structure of the final product form.
16 . The method of claim 15 , wherein the forming precipitates comprises forming at least 0.5 vol. % of the precipitates within the mixed fcc+bcc crystalline structure of the final product form.
17 . The method of claim 16 , wherein the precipitates comprise at least one of L1 2 , L2 1 , B2, Laves, delta, and D0 22 .
18 . The method of claim 16 , wherein the forming precipitates comprise forming at least one of L1 2 , L2 1 , B2, delta, and D0 22 , and wherein the final product form is essentially free of Laves precipitates.
19 . The method of claim 1 , wherein the mixture comprises 20-40 at. % Ni, 20-40 at. % Fe, 5-16 at % Al, 8-26 at. % Cr, and 0.5-10 at. % Ti.
20 . The method of claim 1 , wherein the mixture comprises 20-40 at. % Ni, 20-35 at. % Fe, 6-14 at % Al, and 18-22 at. % Cr, and 1.0-7.0 at. % Ti.