A novel aluminum alloy that can be heat treated after casting by HPDC, GDC, and lpdc

Abstract

The disclosure provides aluminum alloy compositions comprising a rare earth metal such as Ce, La, or mischmetal, Zn, and Mg suitable for high pressure die casting that can be heat treated to achieve increased strength compared to existing Al alloys cast by high pressure die casting (HPDC). The alloy also allows for elimination of solutionizing step in heat treatment of castings made by gravity die casting (GDC) or low pressure die casting (LPDC) to reduce greenhouse gas emissions as well as process cost and processing steps and time while obtaining higher hardness, tensile strength, and yield strength.

Description

A NOVEL ALUMINUM ALLOY THAT CAN BE HEAT TREATED AFTER CASTING BY HPDC, GDC, AND LPDCCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to Indian Provisional Application No. 202311086778 filed December 19, 2023, the disclosure of which is hereby incorporated by reference in its entirety.BACKGROUND

[0002] High pressure die casting (HPDC) is a process for mass manufacturing of aluminum (Al) alloy castings. High production volume castings are frequently made by HPDC. Typically, aluminum alloys that can be cast with HPDC are not heat treatable limiting their strength-especially yield strength. This is because of a high amount of entrapped air and dissolved gases in the casting during processing. Silicon is frequently used for rendering fluidity to Al alloys. Copper is frequently used for development of strength in Al alloys. Precipitation-hardening requires the alloys to be treated to a temperature close to 500 deg C or more for dissolution of elements such as Cu and Si in Al matrix (solutionizing) followed by rapid quenching in water. During the process of solutionizing, gases expand and can form blisters on the surface of the casting making it unusable. As the castings cannot be heated for solutionizing, there is a limit to the strength the alloys can achieve.

[0003] Gravity die casting (GDC) is a process for mass manufacturing of aluminum (Al) alloy castings. Castings that need high mechanical strength are often manufactured by GDC. The castings need to be heat treated for development of mechanical strength. The heat treatment typically comprises solutionizing at a temperature above 500 deg C for an extended period of about 6-12 hrs and quenching in hot water. Due to the thermal shock faced during quenching, there is a high possibility of distortion and cracks in the part. This causes losses not only in terms of material and energy required for manufacturing the parts, but also a lot of energy is consumed in heating and soaking of the castings and heating water for quenching. This increases energy consumption and greenhouse gas (GHG) emissions.

[0004] U.S. Pat. No. 9,963,770 to Rios et al., UT-Battelle, LLC et al. discloses castable high-temperature Ce-modified Al alloys including aluminum and from 5 to 30 wt% of at least one material selected from the group consisting of cerium, lanthanum, and mischmetal.

[0005] U.S. Pat. No. 10,584,403 to Rios et al., UT-Battelle, LLC et al. discloses surface-hardened aluminum-rare earth alloys comprising aluminum, and 4 to 60 wt% of a rare earth element selected from cerium, lanthanum, and mischmetal, or a combination thereof. The Al alloy may optionally further comprise 0-15 wt% magnesium, 0-12 wt% silicon, 0-6 wt% iron, 0-5 wt% nickel, and 0-6 wt% zinc.

[0006] U.S. Pat. No. 11,185,923 to Karlen et al., Hamilton Sundstrand Corp, discloses a method of manufacturing aluminum alloys comprising aluminum, 2-10 wt% cerium, and 0.5-2.5 wt% titanium.

[0007] U.S. Pub. No. 2006 / 0289093 Al discloses an Al-Zn-Mg-Ag high strength alloy for aerospace and automotive castings. The aluminum casting alloy includes 4-5 wt% Zn, 1-3 wt% Mg, up to 1% Cu, and less than about 0.3 wt% Si.

[0008] U.S. Pub. No. 2017 / 0096730 Al to Rios et al., UT-Battelle, LLC et al. discloses a cast alloy including aluminum and from about 5 to about 30 wt percent of at least one of cerium, lanthanum, and mischmetal having a strengthening AI11X3 intermetallic phase, where X is from about 5 to about 30 wt percent of at least one of cerium, lanthanum, and mischmetal.

[0009] U.S. Pub No. 2018 / 0237893 Al to Rios et al. discloses a rapidly solidified aluminum-rare earth element alloy and method of making. Improved mechanical properties without the need for post-processing heat treatments are said to be exhibited.

[0010] U.S. Pat. No. 2021 / 0108292 Al to Moore et al. discloses aluminum -rare earth element alloys comprising an alloying element selected from Si, Cu, Mg, Fe, Ti, Zn, Zr, Mn, Ni, Sr, B and Ca.

[0011] U.S. Pat. No. 2021 / 0130934 Al to Bahl et al. discloses an Al-Ce-Cu alloy comprising 3 to 35 wt% Cu for use in additive manufacturing.

[0012] There is a need for Al alloys that enable heat treating after casting by HPDC to obtain significantly higher yield strength. There is also a need to reduce long, high temperature hardening processes for Al alloys to significantly reduce greenhouse gas emissions.SUMMARY

[0013] The disclosure provides heat treatable aluminum alloy compositions comprising Ce, La, Zn, and Mg suitable for high pressure die casting and also heat treatable alloy compositions for gravity die casting that allow for significant reduction in time of long, high temperature hardening processes to reduce greenhouse gas emissions while obtaining higher tensile strength and yield strength.

[0014] A novel Al alloy is provided that can be heat treated after casting by HPDC. The novel alloy can also be cast by gravity die casting and does not need a separate solutionizing heat treatment before age hardening treatment for strengthening. Al alloys are provided that eliminate the need for elements such as Si or Cu which come out of solution rapidly and hence typically require a separate solutionizing cycle after casting.

[0015] Al alloys are provided including other alloying elements which increase strength by precipitation hardening. Age hardening is ensured by addition of elements such as Zn and Mg, which come out of solution much more slowly. With absence of Si, alternative alloying elements are employed that enable a narrow freezing range and render enough fluidity to the alloy. This can be achieved by adding rare earth elements alloying elements, for example, cerium (Ce) and / or lanthanum (La) among others. By selecting a composition near eutectic composition, a narrow freezing range can be ensured. At the same time the right stoichiometry of Zn and Mg can ensure high strength.

[0016] Uses for the new Al alloy may include various Al alloy castings. For example, the new Al alloy may be used for castings for DC-DC converters, casings for transmissions, casings for transmission and clutch, and castings for electrical enclosures, lights, and the like.

[0017] An inventive aluminum alloy is provided comprising 3.0 to 12.0 wt% of a rare earth element, 3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance ofaluminum. In some cases, the rare earth element comprises predominantly Ce, La, or Mm. In some cases, the rare earth element is selected from the group consisting of Ce, La, and Mm. In some cases, the aluminum alloy does not include Cu or Si.

[0018] An inventive aluminum alloy is provided comprising 3.0 to 12.0 wt% Ce, La, or mischmetal; 3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.0 to 11.0 wt% Ce, La, or mischmetal; 5.0 to 8.0 wt% Zn; 1.2 to 4.0 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 6.5 to about 10.0 wt% Ce, La, or mischmetal; about 5.5 to about 7.5 wt% Zn; and about 1.5 to about 3.0 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 6.5 to about8.5 wt% Ce, La, or mischmetal; about 5.5 to about 7.5 wt% Zn; and about 1.8 to about 3.0 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 7.0 wt% Ce, La, or Mm, about 6.7 wt% Zn, about 2.5 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 7.5 wt% Ce, La, or Mm, about 6.5 wt% Zn, about 2.5 wt% Mg, and a balance of aluminum.

[0019] An inventive aluminum alloy is provided comprising 3.0 to 12.0 wt% Ce or La; 3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.0 to 11.0 wt% Ce or La; 5.0 to 8.0 wt% Zn; 1.2 to 4.0 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 6.5 to about 10.0 wt% Ce or La; about 5.5 to about 7.5 wt% Zn; and about 1.5 to about 3.0 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 6.5 to about 8.5 wt% Ce or La; about 5.5 to about 7.5 wt% Zn; and about 1.8 to about 3.0 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 7.0 wt% Ce or La, about 6.7 wt% Zn, about2.5 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 7.5 wt% Ce or La, about 6.5 wt% Zn, about 2.5 wt% Mg, and a balance of aluminum.

[0020] An inventive aluminum alloy is provided comprising 3.0 to 12.0 wt% Ce;3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.0 to 11.0 wt% Ce; 5.0 to 8.0 wt% Zn; 1.2 to 4.0 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 6.5 to about 10.0 wt% Ce; about 5.5 to about 7.5 wt% Zn; and about 1.5 to about3.0 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 6.5 to about 8.5 wt% Ce; about 5.5 to about 7.5 wt% Zn; and about 1.8 to about 3.0 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 7.0 wt% Ce, about 6.7 wt% Zn, about 2.5 wt% Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises about 7.5 wt% Ce, about 6.5 wt% Zn, about 2.5 wt% Mg, and a balance of aluminum.

[0021] In some cases, the alloy composition does not include Cu. In some cases, the alloy composition does not include added Si. In some cases, the alloy composition does not include added Cu or Si. In some cases, the Al alloy composition includes no more than about 0.5, 0.3 or 0.1 wt% of Cu. In some cases, the Al alloy composition includes no more than about 0.5, 0.3 or 0.1 wt% of Si. In some cases, the amount of cerium and zinc in the alloy composition are sufficient to cause formation of a ternary intermetallic phase of Al-Ce-Zn or Al-La-Zn, or a quaternary phase of Al-Ce-La-Zn. In some cases, the Al alloy composition comprises % Ce > % Mg. In some cases, the Al alloy composition comprises % Ce > % Zn. In some cases, the Al alloy composition comprises % Zn > %Mg. In some cases, the Al alloy composition comprises a ratio of Ce:Zn from 3 : 1 to 1 : 1. In some cases, the Al alloy composition comprises a ratio of Ce:Zn from 3 : 1 to 1.1 : 1. In some cases, the Al alloy composition comprises a ratio of Ce:Zn from 2: 1 to 1.2: 1. In some cases, the Al alloy composition comprises a ratio of Ce:Mg from 12: 1 to 1.1 : 1. In some cases, the Al alloy composition comprises a ratio of Ce:Mg from 8: 1 to 1.3: 1. In some cases, the Al alloy composition comprises a ratio of Ce:Mg from 4: 1 to 1.5: 1. In some cases, the Al alloy composition comprises a ratio of Zn:Mg from 10: 1 to 1.3 to 1. In some cases, the Al alloy composition comprises a ratio of Zn:Mg from 4: 1 to 1.5: 1. In some cases, the aluminum alloy comprises one or more of iron, titanium, zirconium, manganese, chromium, tin, boron, or vanadium in an amount less than 1 wt%, less than 0.8 wt%, less than 0.7 wt%, less than 0.5 wt%, or less than 0.1 wt% for each element taken individually. In some cases, the aluminum alloy contains no more than 1.5 % Fe. In some cases, the aluminum alloy contains no more than 1.3 % Fe. In some cases, the aluminum alloy contains no more than 1.0 % Fe. In some cases, the aluminum alloy contains no more than 0.8 % Fe. In some cases, the aluminum alloy contains no more than 0.5 % Fe. In some cases, the aluminum alloy contains < 0.2 % Fe. In some cases, the aluminum alloy contains < 0.1 % Fe. In some cases, the aluminum alloy contains no more than 1.5 % Mn. In some cases, thealuminum alloy contains no more than 1.3 % Mn. In some cases, the aluminum alloy contains no more than 1.0 % Mn. In some cases, the aluminum alloy contains no more than 0.8 % Mn. In some cases, the aluminum alloy contains no more than 0.5 % Mn. In some cases, the aluminum alloy contains < 0.2 % Mn. In some cases, the aluminum alloy contains < 0.1 % Mn. In some cases, the Al alloy does not include Ag. In some cases, the Al alloy comprises less than 0.05 % Ag.

[0022] A method of making a cast aluminum alloy is provided. In some cases, a method of making a cast aluminum alloy comprises: a. heating pure Al and an Al-Ce, Al -La, or Al -Mm master alloy in a furnace to create a melt; b. adding an Al-Zn master alloy or pure Zn to the melt; c. de-gassing by suitable method, for example, bubbling an inert gas, such as Ar or N2, or any other suitable method followed by slag removal; d. adding an Al-Mg master alloy or pure Mg to the melt; e. holding the melt at a heating temperature and stirring to homogenize the melt; f. removing slag to create a molten charge; and g. pouring the molten charge into a casting mold. In some cases, the heating temperature is in a range of from about 660 deg C to about 760 deg C, or about 700 deg C to about 760 deg C. In some cases, the casting mold is preheated. In some cases, the casting mold is preheated to a temperature in a range of from 150 to 550 deg C, 200 to 525 deg C, or about 500 deg C.

[0023] In some cases, the method comprises high pressure die casting. In some cases, the method further comprises feeding a molten charge of the inventive alloy into the die under high pressure of from about 1,500 psi to about 25,000 psi, about 2,000 to about 20,000 psi, or about 1,000 to 5,000 psi. In some cases, the method comprises opening the die, removing the casting, and allowing the casting to cool to obtain a shaped part. In some cases, the casting is cooled to ambient room temperature. In some cases, the cooling comprises air cooling. In some cases, the cooling comprises quenching in water.

[0024] In some cases, the method comprises gravity die casting. In some cases, the method comprises feeding a molten charge of the inventive alloy into the die under atmospheric pressure gravity feed. In some cases, the method comprises opening the die, removing the casting, and allowing the casting to cool to obtain a shaped part. In some cases, the casting is cooled to ambient room temperature. In some cases, the cooling comprises air cooling. In some cases, the cooling comprises quenching inwater. The cast aluminum alloy can comprise from 3.0 to 12.0 wt% of a rare earth element, 3.5 to 10.0 wt% Zn, and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the rare earth element comprises predominantly Ce, La, or Mm. In some cases, the cast aluminum alloy comprises 6.0 to 11.0 wt% Ce, La, or Mm, 5.0 to 8.0 wt% Zn, and 1.2 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the cast aluminum alloy comprises 6.5 to 10.0 wt% Ce, La, or Mm, 5.5 to 7.5 wt% Zn, 1.5 to 3.0 wt% Mg, and a balance of aluminum. In some cases, the cast aluminum alloy comprises 6.5 to 8.5 wt% Ce, La, or Mm, 5.5 to 7.5 wt% Zn, 1.8 to 3.0 wt% Mg, and a balance of aluminum.

[0025] In some cases, the method comprises heat treating the shaped part. In some cases, the method comprises heat treating the shaped part without solutionizing. In some cases, the heat treating comprises quenching, and naturally or artificially ageing the shaped part to create a heat-treated shaped part. In some cases, the heat treating comprises quenching, and artificially ageing the shaped part to create a heat-treated shaped part without solutionizing. In some cases, the heat treating comprises artificially ageing the shaped part. In some cases, the heat treating comprises artificially ageing the shaped part without solutionizing.

[0026] In some cases, the heat treating comprises artificially ageing the shaped part by holding at one or more temperatures in a range between 120 deg C to 200 deg C for from 2 to 24 hours to provide an artificially aged shaped part. In some cases, the artificially aged shaped part exhibits a hardness of at least 118 HV, at least 120 HV, at least 130 Hv, at least 140 HV, 118-175 HV, or 140-175 HV when measured by ASTM E384-22 at 1,000 gf. In some cases, the artificially aged shaped part without solutionizing exhibits a hardness of at least 100 BHN, at least 110 BHN, at least 120 BHN, at least 130 BHN, when measured by ASTM E10-18. In some cases, the artificially aged shaped part exhibits yield strength of at least about 200 MPa, at least 250 MPa, at least about 300 MPa, or at least about 400 MPa when measured by ASTM E8ZE8M. In some cases, the artificially aged shaped part exhibits a tensile strength of at least about 250 MPa, at least about 300 MPa, at least about 350 MPa, or at least about 400 MPa when measured by ASTM E8ZE8M. In some cases, the artificially aged shaped part exhibits a yield strength of at least about 250 MPa, at least about 300 MPa, at least about 350 MPa, or at least about 400 MPa when measured by ASTM E8ZE8M.In some cases, a shaped part is provided that exhibits a hardness of at least 103 HV when measured by ASTM E384-22 at 1,000 gf. In some cases, the shaped part exhibits a Vickers hardness of at least 140 HV when measured by ASTM E384-22 at 1,000 gf. In some cases, a shaped part is provided that exhibits a Brinell hardness of at least 80 BHN, or at least 85 BHN, after 3 days of natural ageing without any heat treating. In some cases, a shaped part is provided that exhibits a Brinell hardness of at least 100 BHN with only artificial ageing 160 deg C for 4 hours without solutionizing.

[0027] A shaped part is provided comprising a cast aluminum alloy. In some cases, the shaped part comprises a cast aluminum alloy comprising from 3.0 to 12.0 wt% of a rare earth element, 3.5 to 10.0 wt% Zn, and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the shaped part comprises a cast aluminum alloy comprising 3.0 to 12.0 wt% Ce or La or mischmetal; 3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the shaped part comprises a cast aluminum alloy comprising 6.0 to 11.0 wt% Ce or La or mischmetal; 5.0 to 8.0 wt% Zn; and 1.2 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the shaped part comprises a cast aluminum alloy comprising 6.5 to 10.0 wt% Ce or La or mischmetal; 5.5 to 7.5 wt% Zn; and 1.5 to 3.0 wt % Mg, and a balance of aluminum. In some cases, the shaped part comprises a cast aluminum alloy comprising 6.5 to 8.5 wt% Ce or La or mischmetal; 5.5 to 7.5 wt% Zn; and 1.8 to 3.0 wt % Mg, and a balance of aluminum. In some cases, the cast aluminum alloy of the shaped part does not contain Cu or Si. In some cases, the shaped part is selected from the group consisting of a DC-DC converter casting, a transmission casing, a transmission and clutch casing, and castings for electrical enclosures, lights, and the like.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 A shows an existing prior art process comprising gravity die casting (GDC) in which the molten charge is ladled from the crucible into a casting runner until the molten charge enters the riser after completely filling part (left panel). The GDC cast aluminum alloy may be heat treated via a precipitation-hardening process (right panel) comprising solution treatment, quenching and artificial ageing (e.g., ~8 h) to improve the tensile strength of the cast article.

[0029] FIG. IB shows an existing prior art process comprising high pressure die casting (HPDC) in which the molten charge is fed into a die under high pressure. Unfortunately, most aluminum alloys that can be cast with HPDC are typically not heat treatable via a precipitation-hardening process due to the gases / air that dissolve or get entrapped during the HPDC process, unless they are cast by vacuum HPDC which is expensive. This can result in a low tensile strength and / or low yield strength product (e.g., < 200 MPa).

[0030] FIG. 2 shows a process suitable for use with inventive Al alloy composition comprising either gravity die casting (GDC) (upper panel) or HPDC casting (lower panel) and artificial ageing without a solutionizing step resulting in a higher yield strength product, e.g., exhibiting >200 MPa for parts cast by HPDC and 250-300 MPa or higher for parts cast by GDC. Avoiding the solutionizing step can also significantly reduce greenhouse gas emissions.

[0031] FIG. 3 shows a bar graph of Vickers hardness of the inventive aluminum alloy after (A) air cooling or (W) water quenching and ageing for 121 deg C for 4 hours, or ageing at 160 deg C for 4 hours, or completely aged for 4 h at 121 deg C + 4 h at 160 deg C. The hardness after ageing post air cooling is very similar to post water quenching. This demonstrates that artificial ageing of the inventive cast Al alloy directly after HPDC could provide high hardness and strength products without a solutionizing step.

[0032] FIG. 4 shows a bar graph of Brinell hardness of the inventive aluminum alloy after (A) air cooling or (W) water quenching as cast, naturally hardened-3 days, naturally hardened-6 days, artificially age hardened- 160 deg C for 4 hours, and artificially age hardened at 120 deg C for 4 hours and 160 deg C for 4 hours.DETAILED DESCRIPTION OF THE INVENTION

[0033] The present disclosure provides new aluminum alloy compositions that enable heat treating after casting, for example, by HPDC to obtain significantly higher yield strength. The new alloy compositions allow for reduction of long, high temperature hardening processes for Al alloy after casting, for example, by GDC to significantly reduce greenhouse gas emissions.

[0034] Definitions

[0035] The singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0036] The term "and / or" refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0037] The term "about," when referring to a measurable value such as an amount of a compound, dose, time, temperature, and the like, is meant to encompass variations of + / -10%, 5%, 1%, 0.5%, or even 0.1% of the specified amount.

[0038] The terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless otherwise defined, all terms, including technical and scientific terms used in the description, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In the event of conflicting terminology, the present specification is controlling.

[0039] All patents, patent applications and publications referred to herein are incorporated by reference in their entirety.

[0040] Unless otherwise specified, the term “percent,” or “%,” refers to weight percent.

[0041] The embodiments described in one aspect of the present disclosure are not limited to the aspect described. The embodiments may also be applied to a different aspect of the disclosure as long as the embodiments do not prevent these aspects of the disclosure from operating for its intended purpose.

[0042] The term “alloy” refers to a solid or liquid mixture of two or more metals or of one or more metals with certain metalloid elements.

[0043] The term “master alloy” refers to a pre-alloyed concentrate of mixture of alloying elements. A master alloy can be used to add major alloying elements in oneform to the base metal. A master alloy may be a semi-finished product that is commercially available for use as a raw material by the metals industry.

[0044] The term “ambient room temperature” or “ambient temperature” refers to the temperature of the surrounding air. In some cases, the term “ambient room temperature” refers to a temperature in a range of 20 to 30 deg C (68 to 86 deg F). In some cases, ambient room temperature is 25 deg C ± 2.0 deg C (77 deg F ± 3.6 deg F).

[0045] The term “eutectic composition” or structure refers to a homogenous solid mix of atomic and / or chemical species forming a super lattice having a unique molar ratio between the components. At this molar ratio, the mixtures melt as a whole (i.e., all components of the mixture melt simultaneously) at a specific temperature or narrow temperature range (e.g., 1-2 deg) -the eutectic temperature. At other atomic ratios, one component of the mixture will melt at a first temperature and other component(s) will melt at other temperatures.

[0046] The term “rare earth elements” refers to elements selected from the group consisting of Scandium (Sc), Yttrium (Y), Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), and mixtures thereof. In some cases, the mixture of rare earth elements is mischmetal (Mm). In some cases, the mixture of rare earth elements comprises Ce and La. In some cases, the mixture of rare earth elements comprises predominantly Ce. In some cases, the rare earth element is Ce. In some cases, the mixture of rare earth elements comprises predominantly La. In some cases, the rare earth element is La.

[0047] The term “mischmetal” (Mm) refers to an alloy of rare earth elements containing primarily Cerium (Ce) as well as Lanthanum (La), Neodymium (Nd), Praseodymium (Pr), mixed in several proportions. Minor impurities can include Fe, Mg, etc. In some cases, mischmetal comprises up to about 50% Ce and 45% La with the rest to be lesser amounts of Nd and Pr. In some cases, mischmetal comprises Ce and La in a Ce:La ratio of about 2: 1. In some cases, mischmetal comprises 47-70% Ce, balance La / Nd / Pr, and impurities % max Fe 0.3-1.0%, Mg 0.8-1.0%. In some cases, mischmetal comprises 47-70% Ce, balance La. In some cases, mischmetal comprises47-70% Ce, balance La and impurities % max Fe 0.3-1.0%, Mg 0.8-1.0%. In some cases, the Mm does not contain Neodymium (Nd) or Praseodymium (Pr). In some cases, the Mm does not contain Neodymium (Nd). In some cases, the Mm does not contain Praseodymium (Pr).

[0048] The term “castability” refers to a feasibility of an alloy for casting into complex shapes and can be rated in a system of poor (0) to excellent (5). “0” refers to incomplete filling with frequent hot tearing and macro-voids resulting in multiple breaks in casting. “1” refers to incomplete filling of casting mold with hot-tearing and cracking present with abundant micro-voids and moderate number of macro-voids. “2” refers to complete filling of mold with moderate hot-tearing and cracking or complete fill with little hot-tearing or cracking and moderately numerous micro- and macrovoids. “3” refers to complete filling of mold with little hot-tearing or cracking or complete filling with moderate frequency of micro-voids and few macro-voids. “$” refers to complete filling of casting mold with no hot-tearing or cracking, very few macro-voids in combination with very few-micro-voids; or a low / med presence of micro-voids. “5” refers to complete filling of the casting mold with no hot-tearing or cracking, no macro-voids and very few micro-voids.

[0049] The term “hardness” refers to the mechanical resistance of a material (test specimen) to mechanical indentation by another harder body (indenter).

[0050] The term “Vickers hardness” refers to a hardness measurement determined by indenting the test material with an indenter subjected to a load of 0.1 to 100 kgf for a period of time. The hardness test method according to Vickers is described in ISO 6507 (Metallic materials- Vickers hardness test-Part 1 : Test method), ASTM E92, or ASTM E384 (Standard Test Method for Microindentation Hardness of Materials to Vickers and Knoop). Vickers hardness may be expressed in units of HV. A Vickers Hardness Testing Machine may be employed. Unless otherwise specified, Vickers hardness is measured under Micro-Vicker’s hardness test ASTM E384-22 Standard Test Method for Microindentation Hardness of Materials using a square-based pyramidal shaped diamond indenter with face angles of 136 degrees and test forces in the range of 9.8 x 10-3 to 9.8 N (1 to 1000 gf). In some cases, the indenter for aluminum is Vickers diamond and force load is 1000 gf (1 kg).

[0051] The term “Brinell hardness” refers to a hardness measurement determined by ISO 6506 or ASTM E10. Unless otherwise specified, ASTM E10-18 test version is employed. In some cases, the term “Brinell hardness” expressed in units of HBS refers to indenter steel 10mm ball and 500-kgf force, e.g., for aluminum products.

[0052] The term “Rockwell hardness” refers to a hardness measurement made by a differential-depth method where the residual depth of the indent made by the indenter is measured. The deeper a defined indenter penetrates the surface of a test specimen, the softer the material being tested. Rockwell hardness may be determined by standardized test methods such as ISO 6508 or ASTM El 8. The Rockwell hardness (HR) is determined from the residual indentation depth. Th indenter and test force must be specified. For example, under ISO 6508, method HRHW employs a tungsten carbide 1 / 8” metal ball and 60 kgf force, e.g., for aluminum materials. Method HRB refers to a 1 / 16” ball indenter and 100 kg test force.

[0053] The requirement to convert from one hardness test scale to another is covered by various International Standards (ASTM E140 or ISO 18265). Conversion charts are available according to hardness test scale conversion algorithms provided within ASTM E140.

[0054] Standard test methods for tension testing of metallic materials including the aluminum alloys disclosed herein may be performed at room temperature including methods of determining yield strength, yield point elongation, tensile strength, elongation, and reduction of area may be determined by standardized test ASTM E8ZE8M. Unless otherwise specified, ASTM E8ZE8M-22 test version may be employed.

[0055] The term “tensile strength” refers to the maximum tensile stress that a material is capable of sustaining. Tensile strength for aluminum alloys may be determined by standardized test ASTM E8 / E8M. Unless otherwise specified, ASTM E8ZE8M-22 test version may be employed.

[0056] The term “yield strength” or “yield stress” refers to the engineering stress at which, by convention, it is considered that plastic elongation of the material has commenced, i.e., the stress a material can withstand without permanent deformation;the stress at which a material begins to deform plastically. Yield strength for aluminum alloys may be determined by standardized test ASTM E8ZE8M. Unless otherwise specified, ASTM E8 / E8M-22 test version may be employed.

[0057] Alloy Compositions

[0058] Aluminum alloys frequently include silicon which renders fluidity to Al alloys. Fluidity and casting characteristics are typically poor without silicon (e.g., A513). Aluminum alloys frequently include copper for development of strength by precipitation hardening. However, aluminum alloys containing silicon and / or copper don’t have super-saturation after cooling from HPDC. Castings made by HPDC cannot be solution treated as high temperature can form blisters on the surface of the product due to expanding gases.

[0059] The term “A356.0” refers to a known prior art cast aluminum alloy including 7% silicon, 0.3 % magnesium, no more than 0.2 % copper, no more than 0.2 % manganese, no more than 0.1% zinc, and no more than 0.2% iron.

[0060] The term “A357” refers to a known prior art cast aluminum alloy including6.5-7.5 % silicon, 0.04-0.07% beryllium, 0.2% iron, 0.2% copper, 0.4-0.7% magnesium, 0.04-0.2% titanium, 0.1% zinc, 0.1% manganese.

[0061] The term “A380” refers to a known prior art cast aluminum alloy including7.5-9.5 % silicon, 1.3% iron, 3.0-4.0 % copper, 0.3% magnesium, 0.5% manganese, 0.5% nickel, 3.0% zinc, and 0.35% tin. See, for example, NADCA Alloy Data- Aluminum Castings-2021.

[0062] The term “A383” (ADC12) refers to a known prior art cast aluminum alloy including 2.0-3.0 % copper, 0.1 % magnesium, a maximum of 1.3% iron, a maximum of 0.15 % tin, a maximum of 0.3% nickel, 3.0% zinc, 0.5% manganese, 9.5-11.5% silicon, and up to 0.5% other metallic elements. A383 (ADC12) aluminum alloy may be used in cold chamber die casting process.

[0063] The disclosure provides a new aluminum alloy comprising Ce, Zn, and Mg and a method for high strength casting without a solutionizing heat treatment.

[0064] A new aluminum alloy has been developed that is amenable to HPDC and suitable for high strength casting without a solutionizing heat treatment. In the new aluminum alloy, cerium is used ensure good fluidity, narrow freezing range, with retention of precipitation hardening elements Zn and Mg in solution after HPDC. In some cases, no added copper or silicon is employed. The inventive alloy compositions are shown in Table 1.

[0065] Table 1. Exemplary Inventive Aluminum Alloy Compositions

[0066] An inventive aluminum alloy is provided comprising 3.0 to 12.0 wt% of one or more rare earth elements, 4.0 to 10.0 wt% Zn, and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.0 to 11.0 wt% of one or more rare earth elements, 5.0 to 8.0 wt% Zn, and 1.2 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.5 to 10.0 wt% of one or more rare earth elements, 5.5 to 7.5 wt% Zn, and 1.5 to 3.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.5 to 8.5 wt% of one or more rare earth elements, 5.5 to 7.5 wt% Zn, and 1.8 to 3.0 wt % Mg, and a balance of aluminum.

[0067] In some cases, the inventive aluminum alloy comprises 3.0 to 12.0 wt% Ce, La, or Mm, 4.0 to 10.0 wt% Zn, and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.0 to 11.0 wt% Ce, La, or Mm, 5.0 to 8.0 wt% Zn, and 1.2 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.5-10.0 wt% Ce, La, or Mm, 5.5 to 7.5 wt% Zn, and 1.8 to3.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.5-8.5 wt% Ce, La, or Mm, 5.5-7.5 wt% Zn, and 1.8-3.0 wt % Mg, and a balance of Al.

[0068] In some cases, the inventive aluminum alloy comprises 3.0 to 12.0 wt% Ce, 4.0 to 10.0 wt% Zn, and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.0 to 11.0 wt% Ce, 5.0 to 8.0 wt% Zn, and 1.2 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.5-10.0 wt% Ce, 5.5 to 7.5 wt% Zn, and 1.8 to 3.0 wt % Mg, and a balance of aluminum. In some cases, the aluminum alloy comprises 6.5-8.5 wt% Ce, 5.5-7.5 wt% Zn, and 1.8-3.0 wt % Mg, and a balance of Al.

[0069] In some cases, the alloy composition comprises about 7.5 wt% Ce, about 6.5 wt% Zn, and 2.5 wt% Mg, and a balance of Al. In some cases, the alloy composition comprises about 7.0 wt% Ce, about 6.7 wt% Zn, and 2.5 wt% Mg, and a balance of Al.

[0070] In some cases, the alloy composition includes less than 0.1 wt% Cu. In some cases, the inventive Al alloy does not include added Cu. In some cases, the alloy composition does not include added Cu. In some cases, the alloy composition includes less than 0.1 wt% Si. In some cases, the alloy composition does not include Si. In some cases, the inventive Al alloy does not include added Si. In some cases, the inventive Al alloy composition includes no more than 0.1 wt% Cu and no more than 0.1 wt% Si. In some cases, the inventive Al alloy does not include Cu or Si. In some cases, the inventive Al alloy does not include added Cu or Si.

[0071] The aluminum alloy composition of the disclosure may comprise one or more elements such as iron, titanium, zirconium, manganese, chromium, tin, boron, or vanadium in an amount less than 1 wt%, less than 0.5 wt%, or less than 0.1 wt% for each element taken individually. In some cases, the inventive aluminum alloy composition does not include any detectable iron, titanium, zirconium, manganese, chromium, tin, boron, or vanadium.

[0072] Optionally a flux may be added to the aluminum alloy. The main components of the flux may include chloride or fluoride, rare earth halides, rare earth carbonates, or other rare earth compounds. Common fluoride salts such as NasAlFe,CaF2, and Na2SiFe may be employed. Chloride salts such as KC1, MgCh may be employed. Auxiliary additives such as K2CO3, Na2CCh, CaCCh, NaF, KNO3, CaCh, CaSO4, and graphite may also be used. The flux may be employed to prevent excess oxide formation, remove non-metal inclusions, and aid in slag removal.

[0073] Casting methods

[0074] Many advantages of high pressure die casting (HPDC) include higher production rates for high volume manufacturing, good quality parts manufactured, and good uniformity. Thin wall products of thicknesses under 0.4 mm are possible. HPDC allows for use of various die shapes, and the dies used in the HPDC process typically have a durable lifespan which means they can be reused in multiple production cycles to reduce cost of the die casting product.

[0075] Unfortunately, aluminum alloys comprising Cu and / or Si that can be cast with HPDC are typically not heat treatable via a precipitation-hardening process due to the gases / air that dissolve or get entrapped during the HPDC process, unless they are cast by vacuum HPDC, which is expensive. The gases / air can come out of solution when heating for solutionizing, which is an important step of HT of aluminum alloys. The resulting HPDC aluminum alloy product may exhibit low strength of no more than about 150 MPa.

[0076] FIG. 1 A shows an existing prior art process comprising gravity die casting (GDC) in which the molten charge is ladled from the crucible into a casting runner until the molten charge enters the riser, (left panel). After solidification, the die is opened, the product part is removed from the casting, and subjected to precipitation hardening comprising solutionizing (e.g., about 515-579 deg C) for several hours, quenching in cold or hot water, and artificial ageing at about 177 + / 16 deg C for about 8 hours. Although GDC products may be precipitation hardened to improve product strength, gravity die casting is slower and so can be more expensive as compared to HPDC.Sand casting requires a new mold for every production, while permanent mold casting is slower as opposed to HPDC casting.

[0077] FIG. IB shows an existing prior art process comprising high pressure die casting (HPDC) in which the molten charge is fed into a die under high pressure andsolidified to obtain the desired component. The molten metal is forced by an injection piston under high pressure (~ 1,500 to 25,000 psi, e.g., via hydraulic pressure), within the casting cavity, and a press secures it inside. The process takes place rapidly, in some cases, seconds or a fraction of seconds. The mold has to be completely sealed and kept under high pressure for solidification to occur. Hydraulic pressures can compress any gases trapped within the mold and feed the solidification shrinkage during the cooling process. Once solidification is complete, removal of the casting takes place by opening the die. Upon ejection of the final product, the die is locked again from the next production cycle. Typically, high pressure die casting tool comprises two steel blocks that form the two ends of a die cavity to form the desired part. Unfortunately, aluminum alloys comprising Cu and / or Si that can be cast with HPDC are typically not heat treatable via a precipitation-hardening process due to the gases / air that dissolve or get entrapped during the HPDC process. The gases / air can come out of solution when heating for solutionizing, which is an important step of HT of aluminum alloys. Without the precipitation-hardening process the resulting HPDC aluminum alloy product may exhibit low strength of no more than about 150 MPa, or no more than about 200 MPa.

[0078] The inventive Al alloy may be cast by any suitable method including sand casting, gravity die casting (GDC), low pressure die casting (LPDC), or high pressure die casting (HPDC) using a hot chamber die casting machine, or a cold chamber die casting machine. The intermetallic ternary phases of Al-Ce-Zn, Al-La-Zn or the quaternary phase of Al-Ce-La-Zn in the inventive cast Al alloy allow for heat treating without solutionizing to significantly increase hardness of the high strength finished product and result in significant energy savings.

[0079] A method of making a cast aluminum alloy is provided, comprising heating pure Al and an Al-Ce, Al-La, or Al-Mm master alloy in a furnace to create a melt; adding an Al-Zn master alloy to the melt; adding an Al-Mg master alloy to the melt; holding the metal at the heating temperature and stirring to homogenize the melt; removing slag to create a molten charge; and pouring the molten charge into a casting mold, wherein the cast aluminum alloy comprises from about 3.0 to 12.0 wt% Ce, La, or Mm; 3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum. In some cases, the cast aluminum alloy comprises from about 6.0 to about 11.0 wt% Ce,La, or Mm; from about 5.0 to about 8.0 wt% Zn; and about from 1.2 to about 4.0 wt % Mg with the balance being aluminum. In some cases, the cast aluminum alloy comprises from about 6.5 to about 10.0 wt% Ce, La, or Mm; about 5.5 to about 7.5 wt% Zn; and about 1.5 to about 3.0 wt% Mg, and a balance of aluminum. In some cases, the cast aluminum alloy comprises from about 6.5 to about 8.5 wt% Ce, La, or Mm; about 5.5 to about 7.5 wt% Zn; and about 1.8 to about 3.0 wt% Mg, and a balance of aluminum. In some cases, the heating temperature is in a range from about 660 deg C to about 760 deg C.

[0080] In some cases, an aluminum alloy is provided for use in HPDC. In some cases, the aluminum alloy comprises from about 3.0 to about 12.0 wt% Ce, La, or Mm, from about 4.0 to about 10.0 wt% Zn, and about from 1.0 to about 4.0 wt % Mg with the balance being aluminum. In some cases, the aluminum alloy comprises from about 7.5 to about 10.5 wt% Ce, from about 5.5 to about 7.5 wt% Zn, and about from 1.8 to about 3.0 wt % Mg with the balance being aluminum. In some cases, impurities can include Fe and Mn in no more than 1.5 %, no more than 1.0%, no more than 0.8%, no more than 0.5 %, no more than 0.3 %, or no more than 0.1 %.

[0081] In some cases, an aluminum alloy is provided for use in GDC. In some cases, the aluminum alloy comprises from about 3.0 to about 12.0 wt% Ce, La, or Mm, from about 3.5 to about 10.0 wt% Zn, and from about 1.0 to about 4.0 wt % Mg with the balance being aluminum. In some cases, the aluminum alloy comprises from about 6.0 to about 8.5 wt% Ce, from about 5.5 to about 7.5 wt% Zn, and about from 1.7 to about 2.8 wt % Mg with the balance being aluminum. In some cases, impurities can include Fe, Mn, Zr, Ti, P, Sn, B, V, any one of which is present in no more than 1.0 %, no more than 0.8 %, no more than 0.5 %, no more than 0.3 %, or no more than 0. 1%.

[0082] In some cases, the cast aluminum alloy comprises about 7.0 wt% Ce, about 6.7 wt% Zn, about 2.5 wt% Mg, and a balance of aluminum. In some cases, the cast aluminum alloy comprises about 7.5 wt% Ce, La, or Mm, about 6.5 wt% Zn, about 2.5 wt% Mg, and a balance of aluminum.

[0083] The method further comprises opening the die, removing the casting, and allowing the casting to cool to ambient room temperature to obtain a shaped part. In some cases, optionally the cooling comprises air cooling. In some cases, optionally thecooling comprises liquid cooling. In some cases, the shaped part can exhibit a hardness of at least 103 HV when measured by ASTM E384-22 at 1,000 gf.

[0084] The method can further comprise adding a flux and / or other additive to the melt. In some cases, the flux may be optionally added at 5-8 kg / t, 6-8 kg / t or 5-6 kg / t.

[0085] The casting mold may be preheated. In some cases, the casting mold is preheated to a temperature of from about 150 deg C to about 550 deg C, about 200 deg C to about 525 deg C, or about 500 deg C.

[0086] In some cases, the method comprises comprising feeding the molten charge into the die under high pressure, for example, a high pressure of from about 1,500 psi to about 25,000 psi.

[0087] The method may further comprise heat treating the shaped part. In some cases, the heat treating comprises artificially ageing the shaped part by holding at one or more temperatures in a range between 120 deg C to 200 deg C for from 2 to 24 hours. The method may include air cooling the artificially aged shaped part. In some cases, the artificially aged shaped part exhibits a hardness of at least 118 HV when measured by ASTM E384-22 at 1,000 gf. In some cases, the artificially aged shaped part exhibits a micro indentation hardness of at least 118 HV when measured by ASTM E384-22 at 1,000 gf.

[0088] In some cases, the heat treating of the shaped part comprises solutionizing, quenching, and artificially ageing the shaped part to create a heat-treated shaped part. In some cases, the solutionizing comprises heating the shaped part to a solutionizing temperature above the solvus temperature and below the solidus temperature. In some cases, the solutionizing temperature is in a range from about 500 deg C and about 550 deg C. In some cases, the solutionizing is performed for from about 1 to about 12 hours, or about 2 to about 6 hours, or no more than 4 hours. In some cases, the heat- treated shaped part exhibits a hardness of at least 140 HV when measured by ASTM E384-22 at 1,000 gf.

[0089] A shaped part is provided comprising a cast aluminum alloy comprising from about 3.0 to about 12.0 wt% Ce, La, or Mm, from about 3.5 to about 10.0 wt% Zn, and about from 1.0 to about 4.0 wt % Mg with the balance being aluminum. Ashaped part is provided comprising a cast aluminum alloy comprising from about 6.0 to about 11.0 wt% Ce, La, or Mm, from about 5.0 to about 8.0 wt% Zn, and about from 1.2 to about 4.0 wt % Mg with the balance being aluminum. A shaped part is provided comprising a cast aluminum alloy comprising from about 6.5 to about 10.0 wt% Ce, from about 5.5 to about 7.5 wt% Zn, and about from 1.8 to about 3.0 wt % Mg with the balance being aluminum. A shaped part is provided comprising a cast aluminum alloy comprising from about 6.5 to about 8.5 wt% Ce, La, or Mm, from about 5.5 to about 7.5 wt% Zn, and about from 1.8 to about 3.0 wt % Mg with the balance being aluminum. In some cases, the shaped part may be DC-DC converter casting, a transmission casing, or a transmission and clutch casing.

[0090] FIG. 2 shows a process suitable for use with inventive Al alloy comprising either gravity die casting (GDC) (upper panel) or HPDC casting (lower panel) and heat ageing without a solutionizing step resulting in a higher tensile strength and / or higher yield strength product, e.g., exhibiting at least -200 MPa. In some cases, the casting exhibits tensile strength and / or yield strength of at least 300 MPa, at least 350 MPA, or at least - 400 MPa when measured by ASTM E8 / E8M. Avoiding the solutionizing step also significantly reduces greenhouse gas emissions.

[0091] Heat Treatment

[0092] The term “heat treatment” or “heat treating” (HT) refers to heat treating a cast aluminum alloy part. After aluminum cools in the casting process, it exhibits certain “as cast” strength characteristics. Many applications require aluminum castings to have different mechanical properties, metallurgical structure, or tensile strength than an aluminum casing will have “as cast.” Heat treatment is used to strengthen and improve the structure of cast aluminum parts.

[0093] Various standard heat treatments are known including M condition (none-as cast), F condition (as fabricated), O condition (annealed- wrought products only), H condition (cold-worked, strain hardened), T condition (heat treated), T1 condition (partial solution plus natural ageing), T2 condition (annealed cast products only), T3 solution plus cold work), TB condition (solution treated and naturally aged, e.g., T4), TE condition (artificially aged only, e.g., T5 or T51), TB7 condition (solution treated and stabilized), TF condition (solution heat treated and fully artificially aged, e.g., T6),TF7 condition (solution treated and artificially aged and stabilized, e.g., T7 or T71 tempers), T8 condition (solution plus cold work plus artificial ageing), T9 condition (solution plus artificial ageing plus cold work), and TS condition (stress relieved and annealed). A T61 condition includes solutionizing, quenching, and artificial ageing.

[0094] The term “precipitation hardening,” or “precipitation-hardening” is a widely used mechanism for strengthening of Al-Cu alloys. In general, there are only three groups of aluminum alloys that are typically produced by age hardening and can be thermally strengthened: aluminum alloys in the 2000 series, 6000 series, and the 7000 series. The term “precipitation-hardening process” is a three-step process comprising solutionizing (i.e., solid solution treatment), quenching, and artificial aging. For example, in a T6 heat treatment condition the sample is solution treated, quenched, then artificially aged. Specifically, a T6 heat treatment includes three steps as shown in FIG. 1 upper panel.

[0095] The term “solutionizing” or “solid solution treatment” refers to where the alloy is heated above the solvus temperature and soaked (held) there until a homogenous solid solution (alpha, a) is produced. The theta (9) precipitates are dissolved in this step and any segregation present in the original alloy is reduced. Solutionizing is the first step in the precipitation-hardening process. The first step in the precipitation-hardening heat treatment is solutionizing the casting by heating to a very high temperature above the solvus temperature but just below the alloy melting point, e.g., > 500 deg C to about 580 deg C, or about 516 deg C to about 579 deg C, e.g., -538 deg C (-1,000 F) for several hours, e.g., about 1 to about 24 hours, about 2 to about 18 hours, or -12 hours. The third step is artificially ageing the castings in a furnace heated to a temperature below the solvus temperature, e.g., -154 deg C (310 deg F) for several hours, e.g., about 3-5 hours and allowed to cool naturally. The quenching can cause distortion and stress in parts due to extreme temperature differentials.

[0096] The term “quenching” refers to rapid cooling of the sample by lowering into a liquid solution bath, such as water or ethylene glycol at a specific temperature. For example, the quench temperature may be at a specific temperature, e.g., 66-100 deg C (150-214 deg F). In the case of an Al alloy with a precipitation hardening agent or solute such as Cu, the solid solution alpha (a) is rapidly cooled forming asupersaturated solid solution of alphass (ass) which may contain excess copper and is not an equilibrium structure. The atoms do not have time to diffuse to potential nucleation sites and thus theta (9) precipitates do not form. Quenching is the second step in the precipitation-hardening process.

[0097] The term “precipitation ageing,” “aging” or “ageing” or “artificial ageing” treatment is a heat treatment carried out at a temperature above ambient and below the solvus temperature for several hours to produce finely dispersed precipitates.Precipitation ageing produces a finely dispersed precipitate, for example, in an Al alloy with a solute element such as, e.g., Cu, Mg, and / or Zn. The artificial ageing temperature may be in a range of, for example, from about 120 deg C to about 200 deg C (300 to 400 deg F), or about 120 deg C to about 180 deg C, or about 150 deg C to about 180 deg C. The soak (hold) times may be in a range of, for example, from about 2 to about 24 hours, about 4 to about 18 hours, or about 6 to about 12 hours. The supersaturated alpha, ass, is heated below the solvus temperature to produce a finely dispersed precipitate. Atoms diffuse only short distances at this aging temperature. For example, when an Al alloy includes a solute element, because the supersaturated alpha, ass, is not stable, the solute element atoms can diffuse to numerous nucleation sites and precipitates grow. The formation of finely dispersed precipitate in the alloy may be one objective of the precipitation-hardening process. The fine precipitates in the alloy may impede dislocation movement by forcing the dislocations to either cut through the precipitated particles or go around them. By restricting dislocation movement during deformation, the alloy is strengthened. In the precipitation-hardening process, ageing is the third step. Precipitation ageing may be performed under TE condition (T5 or T51). Under T5 conditions, a sample is cooled from an elevated temperature shaping process the artificially aged. A T51 heat treatment bakes the casting at a low temperature to artificially age it. For example, the casting may be heated 3-5 hours at 227 deg C (440 deg F) then allowed to cool naturally.

[0098] The terms “naturally aged” or “natural ageing” in reference to cast aluminum alloys refers to alloys that have undergone a hardening process through natural aging process after casting, where the alloying elements within the metal gradually precipitate out of solution at ambient room temperature improving the metal’s strength and properties without any additional heat treatment steps. Essentially,the metal hardens over time on its own. In some cases, the natural ageing of the aluminum alloy occurs over at least 1 hr, at least 3 h, at least 6 h, at least 12 h, at least 18 h, at least 24 h, at least 1 day, at least 2 days, at least 3 days, at least 5 days, at least 6 days, at least 7 days, at least 8 days, at least 10 days, or at least 15 days or more at ambient room temperature.

[0099] The term “solution treated and stabilized” refers to a T7 condition (T7 or T71) where a cast alloy is solution heat treated then stabilized (overaged). The stabilization occurs at a temperature in a range of 200 to 250 deg C (400-480 deg F) in order to stabilize mechanical properties and can result in slightly lower tensile strength and yield strength but increased elongation value compared to T6 series of heat treatments.

[0100] The term “solvus temperature” refers to the temperature at which a solid solution becomes unstable and separates into different phases. It is a function of the composition of the system and can be represented by a curve or a surface on a phase diagram. Solvus temperature is different from the solidus temperature, which is the temperature at which an alloy starts to melt.

[0101] The term “solution treated and stabilized” refers to a heat treatment such as a T7 or T71 heat treatment similar to T6 except the temperature of the ageing after quench. For T7 castings are aged at 440 deg F (227 deg C) for 7-9 hours. For T71, castings are aged at 475 deg F (204 deg C) for 3-6 hours.

[0102] FIG. 3 shows a bar graph of hardness of the inventive alloy after (A) air cooling or (W) water quenching and ageing for 121 deg C for 4 hours, or ageing at 160 deg C for 4 hours, or completely aged for 4 h at 121 deg C + 4 h at 160 deg C. The hardness after ageing post air cooling is very similar to post water quenching. This demonstrates that ageing the inventive cast Al alloy directly after HPDC could provide high hardness and strength products without solutionizing.

[0103] Table 2 shows hardness of an inventive Al alloy after various conditions and a comparison to prior art alloys A357, A356.0. A380, A383 (ADC12).

[0104] Table 2. Hardness of Representative Inventive Al alloy and prior art Al alloys

[0105] Table 3 shows Brinell hardness of another inventive Al alloy after various conditions.

[0106] Table 3. Hardness of Representative Inventive Al alloy

[0107] The inventive cast Al alloy exhibits the required Brinell hardness of at least 80 BHN, or at least 85 BHN, after about 3 days of natural ageing without any HT, as shown in table 3. The inventive air cooled casting achieves the required hardness of at least 100 BHN with only artificial ageing 160 deg C for 4 hours. The inventive water quenched casting achieves hardness beyond USL after artificial ageing 160 deg C for 4 hrs. The inventive cast Al alloys have been found to exhibit higher yield strength for HPDC castings along with higher yield strength and higher tensile strength for GDC castings compared to conventional Al alloys.EXAMPLES Example 1. Casting Method

[0108] The inventive cast aluminum alloys were cast as follows. Proportions of Al, Ce, Mg and Zn were employed as found in Table 1. For casting commercially pure Al and Al-Ce master alloy were melted in an Induction furnace. Al-Zn and then Al-Mg master alloys were added to the melt in pre-determined proportions. An investment casting mold was heated to 500 deg C in a separate oven. The metal was held at 760 deg C and stirred for homogenization. After removal of slag, the metal was poured intothe investment casting mold. After the samples were cooled, removed from the mold, and prepared by standard metallographic practices, the ‘as cast’ hardness of the samples was measured by ASTM E384 method. Hardness results for ‘as cast’ samples are shown in Table 2. As cast samples exhibited hardness of 103-116 HV1 when tested under ASTM E384-22 under 1000 gf.Example 2. Artificial Ageing of Cast Samples without Solutioning

[0109] Pieces of the as cast sample produced in Example 1 were aged as follows. The samples were soaked first at 120 deg C for 4 hrs followed by 160 deg C for 4 hrs. Hardness was measured by ASTM E384 method after the samples were prepared by standard metallographic practices. After ageing and post air cooling, the samples exhibited hardness of 118-147 HV1 when tested under ASTM E384-22 under 1000 gf, as shown in Table 2. Hardness of the inventive alloy after (A) air cooling or (W) water quenching and ageing for 121 deg C for 4 hours, or ageing at 160 deg C for 4 hours, or completely aged for 4 h at 121 deg C + 4 h at 160 deg is shown in FIG. 4. The hardness after ageing post air cooling was very similar to post water quenching. This demonstrates that artificial ageing the inventive cast Al alloy directly after HPDC can provide high hardness and strength products without a solutionizing heat treatment.Example 3. Solutionizing and Artificial Ageing of Cast Samples with Air Cooling

[0110] Sample pieces of a cast bar of the inventive Al alloy were heat treated comprising solutionizing by heating to -500 deg C in a muffle furnace and soaked for 2 hrs. The pieces were then removed from the furnace and air cooled to room temperature. The pieces were artificially aged at 120 deg C for 4 hrs followed by 160 deg C for 4hrs and air cooled at the end of the cycle. Hardness of the samples was measured after the samples were prepared by standard metallographic practices. After ageing and post air cooling, the samples exhibited hardness of 140-174 HV1 when tested under ASTM E384-22 under 1000 gf, as shown in Table 2.

[0111] Example 4. Casting method by Gravity Die Casting (GDC)

[0112] The inventive cast aluminum alloys were cast as follows. Proportions of Al,Ce, Mg and Zn were employed as found in Table 1. For casting, commercially pure Al (LM0) and Al-MM master alloy were melted in an electrically heated crucible furnace.After degassing using a rotary degassing unit, Al-Zn master alloy and pure Mg were added. A gravity die casting (GDC) mold fitted on a tilt casting machine was heated to 150 - 200°C. Liquid metal was poured in the mould and tilted for solidification. After solidification, the mold was tilted back to pouring position, mold opened and the casting was taken out. Some of the castings were cooled in air and some were directly quenched in water.

[0113] Example 5: Natural Ageing of castings

[0114] As cast samples were kept in air and hardness was measured immediately after solidification, after 3 days after casting and after 6 days after casting. Hardness was measured by Brinell hardness (BHN) using ASTM El 0-18 method. Hardness of air cooled castings increased from as cast hardness of 68 BHN to 85BHN in 3 days and to 86 BHN in 6 days. Hardness of water quenched castings increased from 72 BHN to 86 BHN in 3 days and to 94.5 BHN in 6 days.

[0115] Example 6: Artificial Ageing of castings

[0116] The castings were heated at 160°C for 4 hrs. The hardness was measured by Brinell hardness (BHN) using ASTM El 0-18 method. Hardness of air cooled castings increased to 104 to 110 BHN and hardness of water quenched castings increased to 116 to 122 BHN. On applying ageing cycle of 4hrs at 120°C followed by 160°C for 4hrs, hardness of air cooled castings increased to ~114 BHN and hardness of water quenched castings increased to 135 BHN. Brinell hardness data for a representative inventive Al alloy under various conditions are shown in Table 3 and FIG. 4. FIG. 4 shows a bar graph of Brinell hardness of the inventive aluminum alloy after (A) air cooling or (W) water quenching as cast, naturally hardened-3 days, naturally hardened-6 days, artificially age hardened- 160 deg C for 4 hours, and artificially age hardened at 120 deg C for 4 hours and 160 deg C for 4 hours.

[0117] The inventive cast Al alloy exhibits the required Brinell hardness of at least 80 BHN, or at least 85 BHN, after about 3 days of natural ageing without any HT, as shown in table 3. The inventive air cooled casting achieves the required hardness of at least 100 BHN with only artificial ageing 160 deg C for 4 hours without solutionizing.The inventive water quenched casting achieves hardness of BHN116 after artificial ageing 160 deg C for 4 hrs.

[0118] The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter append.

[0119] Clauses

[0120] Clause 1. An alloy composition comprising 3.0 to 12.0 wt% of a rare earth element, 3.5 to 10.0 wt% Zn, 1.0 to 4.0 wt% Mg, and a balance of aluminum.

[0121] Clause 2. The alloy composition of clause 1, comprising from 3.0 to 12.0 wt% Ce, La, or Mm; 4.0 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum.

[0122] Clause 3. The alloy composition of clause 1 or 2, comprising 6.0 to 11.0 wt% Ce, La, or Mm; 5.0 to 8.0 wt% Zn; 1.2 to 4.0 wt% Mg, and a balance of aluminum.

[0123] Clause 4. The alloy composition of any one of clauses 1-3, comprising about 6.5 to about 10.0 wt% Ce, La, or Mm; about 5.5 to about 7.5 wt% Zn; and about1.5 to about 3.0 wt% Mg, and a balance of aluminum, or optionally comprising about6.5 to about 8.5 wt% Ce, La, or Mm; about 5.5 to about 7.5 wt% Zn; and about 1.8 to about 3.0 wt% Mg, and a balance of aluminum.

[0124] Clause 5. The alloy composition of any one of clauses 1-4, wherein the alloy composition does not include Cu, does not include added Cu, or comprises no more than 0.1 wt% Cu.

[0125] Clause 6. The alloy composition of any one of clauses 1-5, wherein the alloy composition does not include Si, does not include added Si, or comprises no more than 0.1 wt% Si.

[0126] Clause 7. The alloy composition of any one of clauses 1-6, wherein the alloy composition does not include Cu or Si.

[0127] Clause 8. The alloy composition of any one of clauses 1-7, wherein the amount of cerium or lanthanum, and zinc in the alloy composition are sufficient to cause formation of a ternary intermetallic phase of Al-Ce-Zn or Al-La-Zn or a quaternary phase of Al-Ce-La-Zn.

[0128] Clause 9. The alloy composition of any one of clauses 1-8, further comprising one or more of iron, titanium, zirconium, manganese, chromium, tin, boron, or vanadium in an amount less than 1.5 wt%, less than 1.3 wt%, less than 1 wt%, less than 0.8 wt%, less than 0.5 wt%, less than 0.3 wt%, or less than 0.1 wt% for each element taken individually.

[0129] Clause 10. The alloy composition of any one of clauses 1- 9, for use in casting by a method selected from the group consisting of sand casting, gravity die casting (GDC), low pressure die casting (LPDC), high pressure die casting (HPDC), hot chamber die casting machine, and cold chamber die casting machine.

[0130] Clause 11. The alloy composition of any one of clauses 1-10, wherein the alloy composition is a cast aluminum alloy.

[0131] Clause 12. A method of making a cast aluminum alloy, comprising a. heating pure Al and an Al-Ce master alloy, Al-La master alloy, or Al-Mm master alloy in a furnace to create a melt; b. adding an Al-Zn master alloy or pure Zn to the melt; c. adding an Al-Mg master alloy or pure Mg to the melt; d. degassing the melt followed by removing slag to create a clean molten charge; and e. holding the melt at a heating temperature and stirring to homogenize the melt; f. pouring the molten charge into a casting mold, wherein the cast aluminum alloy comprises3.0 to 12.0 wt% Ce, La, or Mm; 3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum;6.0 to 11.0 wt% Ce, La, or Mm; 5.0 to 8.0 wt% Zn; and 1.2 to 4.0 wt % Mg, and a balance of aluminum;6.5 to 10.0 wt% Ce, La, or Mm; 5.5 to 7.5 wt% Zn, 1.5 to 3.0 wt% Mg, and a balance of aluminum; or6.5 to 8.5 wt% Ce, La, or Mm; 5.5 to 7.5 wt% Zn, 1.8 to 3.0 wt% Mg, and a balance of aluminum.

[0132] Clause 13. The method of clause 12, wherein the cast alloy composition does not include Cu, does not include added Cu, or comprises no more than 0.1 wt% Cu.

[0133] Clause 14. The method of clause 12 or 13, wherein the cast alloy composition does not include Si, does not include added Si, or comprises no more than 0.1 wt% Cu.

[0134] Clause 15. The method of any one of clauses 12-14, wherein the cast alloy composition does not include Cu or Si.

[0135] Clause 16. The method of any one of clauses 12-15, wherein the amount of cerium or lanthanum, and zinc in the cast alloy composition are sufficient to cause formation of a ternary intermetallic phase of Al-Ce-Zn or Al-La-Zn or a quaternary intermetallic phase of Al-Ce-La-Zn.

[0136] Clause 17. The method of any one of clauses 12-16, wherein the cast alloy composition further comprises one or more of iron, titanium, zirconium, manganese, chromium, tin, boron, or vanadium in an amount less than 1.5 wt%, less than 1.3 wt%, less than 1 wt%, less than 0.8 wt%, less than 0.5 wt%, less than 0.3 wt%, or less than 0.1 wt% for each element taken individually.

[0137] Clause 18. The method of any one of clauses 12-17, wherein the heating temperature is in a range of from about 660 deg C to about 760 deg C, or about 700 deg C to about 760 deg C.

[0138] Clause 19. The method of any one of clauses 12-18, wherein the casting mold is preheated, optionally wherein the casting mold is preheated, optionally wherein the casting mold is preheated to a temperature in a range of from 150 to 550 deg C, 200to 525 deg C, or about 500 deg C, or a metallic mold is preheated to 100 to 400°C, 125 to 350°C, or 150 to 300°C.

[0139] Clause 20. The method of any one of clauses 12-19, further comprising feeding the molten charge into the die under high pressure of from about 1,500 psi to about 25,000 psi, about 2,000 to about 20,000 psi, or about 1,000 to 5,000 psi or pouring the molten charge into the die on a gravity die casting machine.

[0140] Clause 21. The method of any one of clauses 12-20, further comprising opening the die, removing the casting, and allowing the casting to cool to ambient room temperature to obtain a shaped part, optionally wherein the cooling comprises air cooling or water quenching.

[0141] Clause 22. The method of any one of clauses 12-21, wherein the shaped part exhibits a hardness of at least 103 HV when measured by ASTM E384-22 at 1,000 gf. and / or a Brinell hardness of at least 80 BHN, or at least 85 BHN, after about 3 days of natural ageing, a Brinell hardness of at least 90 BHN or at least 95 BHN after about 6 days of natural ageing when measured by ASTM El 0-18.

[0142] Clause 23. The method of any one of clauses 12-22, further comprising heat treating the shaped part.

[0143] Clause 24. The method of clause 23, wherein the heat treating comprises artificially ageing the shaped part by holding at one or more temperatures in a range between 120 deg C to 200 deg C for from 2 to 24 hours to provide an artificially aged shaped part, optionally wherein the artificially aged shaped part exhibits a hardness of at least 118 HV, at least 140 HV, 118-175 HV, or 140-175 HV when measured by ASTM E384-22 at 1,000 gf, further optionally wherein the artificially aged shaped part exhibits a tensile strength of at least about 200 MPa, at least about 250 MPa, at least about 300 MPa, or at least about 400 MPa when measured by ASTM E8ZE8M; further optionally wherein the artificially aged shaped part exhibits a yield strength of at least about 200 MPa, at least about 250 MPa, at least about 300 MPa, or at least about 400 MPa when measured by ASTM E8ZE8M; or at least 100 BHN, at least 120 BHN, at least 130 BHN, at least 140 BHN, or at least 150 BHN when measure by ASTM E10- 18.

[0144] Clause 25. The method of clause 23 or 24, wherein the heat treating comprises quenching, and artificially ageing the shaped part to create a heat-treated shaped part.

[0145] Clause 26. The method of any one of clauses 23-25, wherein the heat treating comprises air cooling, and artificially ageing or naturally ageing the shaped part to create a heat-treated shaped part.

[0146] Clause 27. The method of any one of clauses 23-26, wherein the heat treating does not include solutionizing the shaped part.

[0147] Clause 28. The method of any one of clauses 23-27, wherein the heat- treated shaped part exhibits a hardness of at least 120 HV, at least 130 HV, or at least 140 HV when measured by ASTM E384-22 at 1,000 gf.

[0148] Clause 29. A shaped part comprising a cast aluminum alloy comprising3.0 to 12.0 wt% Ce, La, or Mm; 3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum;6.0 to 11.0 wt% Ce, La, or Mm; 5.0 to 8.0 wt% Zn; and 1.2 to 4.0 wt % Mg, and a balance of aluminum;6.5 to 10.0 wt% Ce, La, or Mm; 5.5 to 7.5 wt% Zn; 1.5 to 3.0 wt% Mg, and a balance of aluminum; or6.5 to 8.5 wt% Ce, La, or Mm; 5.5 to 7.5 wt% Zn; 1.8 to 3.0 wt% Mg, and a balance of aluminum, wherein the cast aluminum alloy does not include Cu or Si

[0149] Clause 30. The shaped part of clause 29, wherein the shaped part is selected from the group consisting of a DC-DC converter casing, a transmission casing, a transmission and clutch casing, housing for lights, power supplies, and enclosures for electrical equipment.

Claims

WHAT IS CLAIMED IS:

1. An alloy composition comprising 3.0 to 12.0 wt% of a rare earth element, 3.5 to 10.0 wt% Zn, 1.0 to 4.0 wt% Mg, and a balance of aluminum.

2. The alloy composition of claim 1, comprising from 3.0 to 12.0 wt% Ce, La, or Mm; 4.0 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum.

3. The alloy composition of claim 1, comprising 6.0 to 11.0 wt% Ce, La, or Mm; 5.0 to 8.0 wt% Zn; 1.2 to 4.0 wt% Mg, and a balance of aluminum.

4. The alloy composition of claim 1, comprising about 6.5 to about 10.0 wt% Ce, La, or Mm; about 5.5 to about 7.5 wt% Zn; and about 1.5 to about 3.0 wt% Mg, and a balance of aluminum.

5. The alloy composition of claim 1, comprising about 6.5 to about 8.5 wt% Ce, La, or Mm; about 5.5 to about 7.5 wt% Zn; and about 1.8 to about 3.0 wt% Mg, and a balance of aluminum.

6. The alloy composition of any one of claims 1-5, wherein the alloy composition does not include Cu, does not include added Cu, or comprises no more than 0.1 wt% Cu.

7. The alloy composition of any one of claims 1-5, wherein the alloy composition does not include Si, does not include added Si, or comprises no more than 0.1 wt% Si.

8. The alloy composition of any one of claims 1-5, wherein the alloy composition does not include Cu or Si.

9. The alloy composition of any one of claims 1-8, wherein the amount of cerium or lanthanum, and zinc in the alloy composition are sufficient to cause formation of a ternary intermetallic phase of Al-Ce-Zn or Al-La-Zn or a quaternary phase Al-Ce-La-Zn.

10. The alloy composition of any one of claims 1-9, further comprising one or more of iron, titanium, zirconium, manganese, chromium, tin, boron, or vanadium in an amount less than 1 wt%, less than 0.8 wt%, less than 0.5 wt%, less than 0.3 wt%, or less than 0.1 wt% for each element taken individually.

11. The alloy composition of any one of claims 1-10, wherein the alloy composition is a cast aluminum alloy.

12. The alloy composition of any one of claims 1-11, for use in casting by a method selected from the group consisting of sand casting, gravity die casting (GDC), low pressure die casting (LPDC), high pressure die casting (HPDC), hot chamber die casting machine, and cold chamber die casting machine.

13. A method of making a cast aluminum alloy, comprising a. heating pure Al and an Al-Ce master alloy, Al-La master alloy, or Al-Mm master alloy in a furnace to create a melt; b. adding an Al-Zn master alloy or pure Zn to the melt; c. adding an Al-Mg master alloy or pure Mg to the melt; d. degassing the melt followed by removing slag to create a clean molten charge; e. holding the melt at a heating temperature and stirring to homogenize the melt; and f. pouring the molten charge into a casting mold, wherein the cast aluminum alloy comprises3.0 to 12.0 wt% Ce, La, or Mm; 3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum;6.0 to 11.0 wt% Ce, La, or Mm; 5.0 to 8.0 wt% Zn; and 1.2 to 4.0 wt % Mg, and a balance of aluminum;6.5 to 10.0 wt% Ce, La, or Mm; 5.5 to 7.5 wt% Zn, 1.5 to 3.0 wt% Mg, and a balance of aluminum; or6.5 to 8.5 wt% Ce, La, or Mm; 5.5 to 7.5 wt% Zn, 1.8 to 3.0 wt% Mg, and a balance of aluminum, optionally wherein the cast aluminum alloy comprises less than 0.1 wt% Cu, comprises less than 0.1 wt% Si, comprises less than 0.1 wt% Cu and less than 0.1 wt% Si, or does not comprise Cu or Si,optionally further comprising one or more of iron, titanium, zirconium, manganese, chromium, tin, boron, or vanadium in an amount less than 1 wt%, less than 0.8 wt%, less than 0.5 wt%, less than 0.3 wt%, or less than 0.1 wt% for each element taken individually.

14. The method of claim 13, wherein the heating temperature is in a range of from about 660 deg C to about 760 deg C, or about 700 deg C to about 760 deg C.

15. The method of claim 13, wherein the casting mold is preheated, optionally wherein the casting mold is preheated, optionally wherein a ceramic casting mold is preheated to a temperature in a range of from 450 to 550 deg C, or 475 to 525 deg C, or a metallic mold is preheated to 100 to 400°C, 125 to 350°C, or 150 to 300°C.

16. The method of claim 13, further comprising feeding the molten charge into the die under high pressure of from about 1,000 psi to about 25,000 psi, about 2,000 to about 20,000 psi, or about 1,000 to 5,000 psi; or pouring the molten charge into the die on a gravity die casting machine.

17. The method of claim 13, further comprising opening the die, removing the casting, and allowing the casting to cool to ambient room temperature to obtain a shaped part, optionally wherein the cooling comprises air cooling or water quenching.

18. The method of claim 13, wherein the shaped part exhibits a hardness of at least 103 HV when measured by ASTM E384-22 at 1,000 gf, and / or a Brinell hardness of at least 80 BHN, or at least 85 BHN, after about 3 days of natural ageing, a Brinell hardness of at least 90 BHN or at least 95 BHN after about 6 days of natural ageing when measured by ASTM E10-18.

19. The method of claim 13, further comprising heat treating the shaped part.

20. The method of claim 19, wherein the heat treating comprises artificially ageing the shaped part by holding at one or more temperatures in a range between 120 deg C to 200 deg C for from 2 to 24 hours to provide an artificially aged shaped part, optionally wherein the artificially aged shaped part exhibits at least one of: a Vickers hardness of at least 118 HV, at least 140 HV, 118-175 HV, or 140-175 HV when measured by ASTM E384-22 at 1,000 gf;a Brinell hardness of at least 100 BHN when measured by ASTM El 0-18, a yield strength of at least about 200 MPa, at least about 250 MPa, at least about 300 MPa, at least about 350 MPa, or at least about 400 MPa when measured by ASTM E8ZE8M; and / or a tensile strength of at least about 200 MPa, at least about 250 MPa, at least about 300 MPa, at least about 350 MPa, or at least about 400 MPa when measured by ASTM E8ZE8M.

21. The method of claim 19, wherein the heat treating comprises quenching, and artificially ageing or naturally ageing the shaped part to create a heat-treated shaped part.

22. The method of claim 19, wherein the heat treating comprises air cooling, and artificially ageing or naturally ageing the shaped part to create a heat-treated shaped part.

23. The method of claim 19, wherein the heat treating does not include solutionizing the shaped part.

24. The method of claim 19, wherein the heat-treated shaped part exhibits a hardness of at least 120 HV, at least 130 HV, or at least 140 HV when measured by ASTM E384-22 at 1,000 gf; or at least 100 BHN, at least 120 BHN, at least 130 BHN, or at least 140 BHN when measured by ASTM E10-18.

25. A shaped part comprising a cast aluminum alloy comprising3.0 to 12.0 wt% Ce, La, or Mm; 3.5 to 10.0 wt% Zn; and 1.0 to 4.0 wt % Mg, and a balance of aluminum;6.0 to 11.0 wt% Ce, La, or Mm; 5.0 to 8.0 wt% Zn; and 1.2 to 4.0 wt % Mg, and a balance of aluminum;6.5 to 10.0 wt% Ce, La, or Mm; 5.5 to 7.5 wt% Zn; 1.5 to 3.0 wt% Mg, and a balance of aluminum; or6.5 to 8.5 wt% Ce, La, or Mm; 5.5 to 7.5 wt% Zn; 1.8 to 3.0 wt% Mg, and a balance of aluminum, wherein the cast aluminum alloy does not include Cu or Si.

26. The shaped part of claim 25, wherein the shaped part is selected from the group consisting of a DC-DC converter casing, a transmission casing, a transmission and clutch casing, housing for lights, power supplies, and enclosures for electrical equipment.

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