Grain refiner for aluminum alloys

Abstract

It has been presently found that calcium and boron can be used together as a grain refiner forming CaB6 particles for aluminum alloys to replace titanium based refiners. Accordingly, there is provided an aluminum alloy comprising: up to 2.0 wt. % of Fe; up to 12 wt. % of Si; up to 1.5 wt. % Mg; up to 1.5 wt. % Mn; up to 0.15 wt. % Zr; up to 6 wt. % of Ni; up to 0.3 wt. % of Cu; from 100 to 500 ppm of B; from 70 to 1000 ppm of Ca; and up to 0.3 wt. % of impurities; wherein the balance is aluminium.

Description

GRAIN REFINER FOR ALUMINUM ALLOYSCROSS-REFERENCE TO A RELATED APPLICATION

[0001] This disclosure claims priority from U.S. provisional application No. 63 / 759,687 filed on February 18, 2025, which is incorporated by reference in its entirety.TECHNICAL FIELD

[0002] This disclosure relates to the field of aluminum alloys and grain refiners for aluminum alloys.BACKGROUND OF THE ART

[0003] The demand for aluminum alloys, for example electrically conducting aluminum alloy is on the rise, particularly in the context of electrical vehicles (EV). One example of alloys that have been used for EV components are the 1xxx foundry alloys. Other common electrical alloys are those of the 6xxx and 8xxx series. In the industrial production of conducting aluminum alloys, grain refinement is a critical process. Grain refinement has the purpose of enhancing the alloy’s mechanical properties and castability. Traditional methods often rely on the addition of titanium based grain refiners such as TiB2 or TiC. However, these traditional methods that rely on titanium grain refiners have limitations in terms of efficiency and cost. Specifically, the efficiency is almost zero in the case where a large amount of boron was added to the alloy to remove the unwanted impurities (e.g. Ti, V, Mn, Cr and Zr) in the alloy that have a detrimental impact on the electrical conductivity. Another drawback of titanium grain refiners is that an excess of titanium is required to activate the TiB2 or TiC particles in the metal and this excess titanium has detrimental effects on the conductivity. Accordingly, it would be highly desired to be provided with a grain refiner that has an improved performance compared to traditional titanium based grain refiner. Moreover, in the context of electrically conductive alloys, it would be desired to have a grain refiner that has limited or no negative impact on the electrical conductivity of the alloy.SUMMARY

[0004] In one aspect of the present disclosure, there is provided an aluminum alloy, comprising: up to 2.0 wt. % of Fe; up to 12 wt. % of Si; up to 1.5 wt. % Mg; up to 1.5 wt. % Mn; up to 0.15 wt. % Zr; up to 6 wt. % of Ni; up to 0.3 wt. % of Cu; from 100 to 500 ppm of B; from 70 to 1000 ppm of Ca; and up to 0.3 wt. % of impurities; wherein the balance is aluminium.

[0005] In at least some embodiments, the aluminum alloy comprises less than 0.05 wt. % of Zr.

[0006] In at least some embodiments, the impurities comprise less than 0.05 wt. % of V.

[0007] In at least some embodiments, the aluminum alloy comprises less than 0.05 wt. % of Mg.

[0008] In at least some embodiments, the aluminum alloy comprises less than 0.05 wt. % of Cu.

[0009] In at least some embodiments, the impurities comprise less than 0.01 wt. % of Ti.

[0010] In at least some embodiments, the impurities comprise less than 0.05 wt. % of Sr.

[0011] In at least some embodiments, the impurities comprise one or more of Ce, Zn, Be, Bi, Ga, Ni, Pb, P, Co, and Sn, each in a concentration of less than 0.01 wt. %.

[0012] In at least some embodiments, B is present in a concentration of from 100to400 ppm.

[0013] In at least some embodiments, Ca is present in a concentration of from 100 to 300 ppm.

[0014] In at least some embodiments, B and Ca are present in a weight ratio of Ca:B of from 1:3 to 1.3:1.

[0015] In at least some embodiments, B and Ca are present in an atomic ratio of Ca:B of from 5.5:1 to 6.5:1.

[0016] In at least some embodiments, B and Ca are present in an atomic ratio of Ca:B of 1:6 ±5%.

[0017] In a further aspect, there is provided an electrical aluminum alloy, comprising: up to 2.0 wt. % of Fe; up to 0.3 wt. % of Si; from 100 to 500 ppm of B; from 70 to 1000 ppm of Ca; and up to 0.3 wt. % of impurities; wherein the balance is aluminium.

[0018] In at least some embodiments, the impurities comprise less than 0.01 wt. % of Ti.

[0019] In at least some embodiments, the impurities comprises Ti, Cr, Mn, V and the total of Ti, Cr, Mn, V is less than 0.05 wt. %.

[0020] In at least some embodiments, B and Ca are present in a weight ratio of Ca:B of from 1:3 to 1.3:1.

[0021] In still a further aspect, there is provided a process of making aluminum part, the process comprising: melting an aluminum alloy comprising up to 2.0 wt. % of Fe; up to 0.6 wt. % Mg, up to 0.65 wt. % Mn, up to 0.15 wt. % Zr and up to 10 wt. % of Si to obtain a molten alloy; adding to the molten alloy from 100 to 500 ppm of B and from 70 to 300 ppm of Ca; and solidifying the molten alloy to obtain the aluminum part. The process is for example a Properzi process or a foundry casting process.

[0022] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 A is an image showing the top surface of an aluminum bar made with the control alloy (only 400 ppm B addition).

[0024] FIG. 1 B is an image showing the top surface of an aluminum bar made with an addition of 400 ppm B and 200 ppm Sr to the alloy.

[0025] FIG. 1C is an image showing the bottom surface of an aluminum bar made with the control alloy (only 400 ppm B addition).

[0026] FIG. 1D is an image showing the bottom surface of an aluminum bar made with an addition of 400 ppm B and 200 ppm Sr to the alloy.

[0027] FIG. 1E is an image showing a first lateral surface of an aluminum bar made with the control alloy (only 400 ppm B addition).

[0028] FIG. 1F is an image showing a first lateral surface of an aluminum bar made with an addition of 400 ppm B and 200 ppm Sr to the alloy.

[0029] FIG. 1G is an image showing a second lateral surface opposite the first lateral surface of an aluminum bar made with the control alloy (only 400 ppm B addition).

[0030] FIG. 1H is an image showing a second lateral surface opposite first the lateral surface of an aluminum bar made with the alloy the addition of 400 ppm B addition and 200 ppm.

[0031] FIG. 2A is a cross section showing the control bar after Poulton attack.

[0032] FIG. 2B is a cross section showing the bar made from the alloy with the addition of 400 ppm B and 200 ppm Sr.

[0033] FIG. 2C is a cross section showing the cooling zone of the control bar.

[0034] FIG. 2D is a cross section showing the cooling zone of the bar made from the alloy with the addition of 400 ppm B and 200 ppm Sr.

[0035] FIG. 3A is an image showing the presence of worm hole in the control alloy.

[0036] FIG. 3B is an image showing the presence of worm hole in the alloy with the addition of 400 ppm B and 200 ppm Sr.

[0037] FIG. 4A is a microscopy image of the polished control alloy (scale bar 500 pm, 100x magnification).

[0038] FIG. 4B is a microscopy image of the polished alloy with the addition of 400 ppm B and 200 ppm Sr (scale bar 500 pm, 100x magnification).

[0039] FIG. 4C is a microscopy image of the polished control alloy (scale bar 40 pm, 1000x magnification).

[0040] FIG. 4D is a microscopy image of the polished alloy with the addition of 400 ppm B and 200 ppm Sr (scale bar 40 pm, 1000x magnification).

[0041] FIG. 4E is an electron microscopy image of the polished control alloy.

[0042] FIG. 4F is an electron microscopy image of the polished alloy with the addition of 400 ppm B and 200 ppm Sr.

[0043] FIG. 4G is a mass spectrum analysis showing that B-AI-Sr particles were formed.

[0044] FIG. 5A is a cross section of a bar made with an aluminum alloy with 300 ppm B addition showing the grain structure after Poulton attack.

[0045] FIG. 5B is a cross section of a bar made with an aluminum alloy with 300 ppm B and 200 ppm Ca additions showing its grain structure.

[0046] FIG. 5C is a cross section of a bar made with an aluminum alloy with a stoichiometric boron addition, showing the grain structure after Poulton attack.

[0047] FIG. 5D is a cross section of a bar made with an aluminum alloy with a stoichiometric boron (B = Ti / 2 + V / 2) and 0.2 wt. % TiC additions, showing the grain structure after Poulton attack.

[0048] FIG. 5E is a cross section of a bar made with an aluminum alloy with 300 ppm B and 400 ppm Sr additions showing the grain structure after Poulton attack.

[0049] FIG. 5F is a cross section of a bar made with an aluminum alloy with 400 ppm boron and 0.8 wt. % TiC additions, showing the grain structure after Poulton attack.

[0050] FIG. 5G is a cross section of a bar made with an aluminum alloy with 500 ppm boron and 1.6 wt. % TiC additions, showing the grain structure after Poulton attack.

[0051] FIG. 5H is a cross section of a bar made with an aluminum alloy with 600 ppm boron and 2.4 wt. % TiC additions, showing the grain structure after Poulton attack.

[0052] FIG. 6A shows the grain structure of an aluminum alloy without any additions after Poulton attack based on the TP-1 method.

[0053] FIG.6B shows the grain structure of an aluminum alloy with 300 ppm of B after Poulton attack based on the TP-1 method.

[0054] FIG. 6C shows the grain structure of an aluminum alloy with 300 ppm of B and 50 ppm of Ca, after Poulton attack based on the TP-1 method.

[0055] FIG. 6D shows the grain structure of an aluminum alloy with 300 ppm of B and 100 ppm of Ca, after Poulton attack based on the TP-1 method.

[0056] FIG. 6E shows the grain structure of an aluminum alloy with 300 ppm of B and 150 ppm of Ca, after Poulton attack based on the TP-1 method.

[0057] FIG. 6F shows the grain structure of an aluminum alloy with 300 ppm of B and 200 ppm of Ca, after Poulton attack based on the TP-1 method.

[0058] FIG. 6G shows the grain structure of an aluminum alloy with 300 ppm of B and 250 ppm of Ca, after Poulton attack based on the TP-1 method.

[0059] FIG. 6H shows the grain structure of an aluminum alloy with 300 ppm of B and 300 ppm of Ca, after Poulton attack based on the TP-1 method.

[0060] FIG. 7A shows the grain structure of an aluminum alloy without any additions after Poulton attack based on the Opticast method.

[0061] FIG.7B shows the grain structure of an aluminum alloy with 300 ppm of B after Poulton attack based on the Opticast method.

[0062] FIG. 7C shows the grain structure of an aluminum alloy with 300 ppm of B and 50 ppm of Ca, after Poulton attack based on the Opticast method.

[0063] FIG. 7D shows the grain structure of an aluminum alloy with 300 ppm of B and 100 ppm of Ca, after Poulton attack based on the Opticast method.

[0064] FIG. 7E shows the grain structure of an aluminum alloy with 300 ppm of B and 150 ppm of Ca, after Poulton attack based on the Opticast method.

[0065] FIG. 7F shows the grain structure of an aluminum alloy with 300 ppm of B and 200 ppm of Ca, after Poulton attack based on the Opticast method.

[0066] FIG. 7G shows the grain structure of an aluminum alloy with 300 ppm of B and 250 ppm of Ca, after Poulton attack based on the Opticast method.

[0067] FIG. 7H shows the grain structure of an aluminum alloy with 300 ppm of B and 300 ppm of Ca, after Poulton attack based on the Opticast method.

[0068] FIG. 8A is an optical microscopy image of the alloy of Fig. 7F at magnification of 100x (scale bar 250 pm).

[0069] FIG. 8B is a close-up of a first zone of Fig. 8A (magnification 500x, scale bar 50 pm), the arrows show the CaBe particles.

[0070] FIG. 8C is a close-up of a second zone of Fig. 8A (magnification 500x, scale bar 50 pm), the arrows show the CaBe particles.

[0071] FIG. 9A is an electron microscopy image of a CaBe particle that was used for the energy dispersive X-ray spectroscopy (EDS) analysis.

[0072] FIG. 9B is an EDS spectrum obtained based on Fig. 9A.

[0073] FIG. 10A is a line scan electron microscopy image on a CaB6particle.

[0074] FIG. 10B is a graph showing the elements identified along the line of Fig. 10A.

[0075] FIG. 11A is another line scan electron microscopy image on another CaB6particle.

[0076] FIG. 11B is a graph showing the elements identified along the line of Fig. 11 A.

[0077] FIG. 12A shows the grain structure of a 1350 aluminum alloy produced at a temperature of 700 °C with stoichiometric B addition, after Poulton attack based on the Opticast method.

[0078] FIG. 12B shows the grain structure of a 1350 aluminum alloy produced at a temperature of 700 °C with stoichiometric B addition, after Poulton attack based on the TP-1 method.

[0079] FIG. 12C shows the grain structure of a 1350 aluminum alloy produced at a temperature of 725 °C with stoichiometric B addition, after Poulton attack based on the Opticast method.

[0080] FIG. 12D shows the grain structure of a 1350 aluminum alloy produced at a temperature of 725 °C with stoichiometric B addition, after Poulton attack based on the TP-1 method.

[0081] FIG. 12E shows the grain structure of a 1350 aluminum alloy produced at a temperature of 750 °C with stoichiometric B addition, after Poulton attack based on the Opticast method.

[0082] FIG. 12F shows the grain structure of a 1350 aluminum alloy produced at a temperature of 750 °C with stoichiometric B addition, after Poulton attack based on the TP-1 method.

[0083] FIG. 12G shows the grain structure of a 1350 aluminum alloy produced at a temperature of 775 °C with stoichiometric B addition, after Poulton attack based on the Opticast method.

[0084] FIG. 12H shows the grain structure of a 1350 aluminum alloy produced at a temperature of 775 °C with stoichiometric B addition, after Poulton attack based on the TP-1 method.

[0085] FIG. 121 shows the grain structure of a 1350 aluminum alloy produced ata temperature of 800 °C with stoichiometric B addition, after Poulton attack based on the Opticast method.

[0086] FIG. 12J shows the grain structure of a 1350 aluminum alloy produced at a temperature of 800 °C with stoichiometric B addition, after Poulton attack based on the TP-1 method.

[0087] FIG. 12K shows the grain structure of a 1350 aluminum alloy produced at a temperature of 825 °C with stoichiometric B addition, after Poulton attack based on the Opticast method.

[0088] FIG. 12L shows the grain structure of a 1350 aluminum alloy produced at a temperature of 825 °C with stoichiometric B addition, after Poulton attack based on the TP-1 method.

[0089] FIG. 12M shows the grain structure of a 1350 aluminum alloy produced at a temperature of 850 °C with stoichiometric B addition, after Poulton attack based on the Opticast method.

[0090] FIG. 12N shows the grain structure of a 1350 aluminum alloy produced at a temperature of 850 °C with stoichiometric B addition, after Poulton attack based on the TP-1 method.

[0091] FIG. 13A shows the grain structure of a 1350 aluminum alloy produced at a temperature of 700 °C with an addition of 300 ppm B, after Poulton attack based on the Opticast method.

[0092] FIG. 13B shows the grain structure of a 1350 aluminum alloy produced at a temperature of 700 °C with an addition of 300 ppm B, after Poulton attack based on the TP-1 method.

[0093] FIG. 13C shows the grain structure of a 1350 aluminum alloy produced at a temperature of 725 °C with an addition of 300 ppm B, after Poulton attack based on the Opticast method.

[0094] FIG. 13D shows the grain structure of a 1350 aluminum alloy produced at a temperature of 725 °C with an addition of 300 ppm B, after Poulton attack based on the TP-1 method.

[0095] FIG. 13E shows the grain structure of a 1350 aluminum alloy produced at a temperature of 750 °C with an addition of 300 ppm B, after Poulton attack based on the Opticast method.

[0096] FIG. 13F shows the grain structure of a 1350 aluminum alloy produced at a temperature of 750 °C with an addition of 300 ppm B, after Poulton attack based on the TP-1 method.

[0097] FIG. 13G shows the grain structure of a 1350 aluminum alloy produced at a temperature of 775 °C with an addition of 300 ppm B, after Poulton attack based on the Opticast method.

[0098] FIG. 13H shows the grain structure of a 1350 aluminum alloy produced at a temperature of 775 °C with an addition of 300 ppm B, after Poulton attack based on the TP-1 method.

[0099] FIG. 131 shows the grain structure of a 1350 aluminum alloy produced ata temperature of 800 °C with an addition of 300 ppm B, after Poulton attack based on the Opticast method.

[0100] FIG. 13J shows the grain structure of a 1350 aluminum alloy produced at a temperature of 800 °C with an addition of 300 ppm B, after Poulton attack based on the TP-1 method.

[0101] FIG. 13K shows the grain structure of a 1350 aluminum alloy produced at a temperature of 825 °C with an addition of 300 ppm B, after Poulton attack based on the Opticast method.

[0102] FIG. 13L shows the grain structure of a 1350 aluminum alloy produced at a temperature of 825 °C with an addition of 300 ppm B, after Poulton attack based on the TP-1 method.

[0103] FIG. 13M shows the grain structure of a 1350 aluminum alloy produced at a temperature of 850 °C with an addition of 300 ppm B, after Poulton attack based on the Opticast method.

[0104] FIG. 13N shows the grain structure of a 1350 aluminum alloy produced at a temperature of 850 °C with an addition of 300 ppm B, after Poulton attack based on the TP-1 method.

[0105] FIG. 14A shows the grain structure of a 1350 aluminum alloy produced at a temperature of 700 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the Opticast method.

[0106] FIG. 14B shows the grain structure of a 1350 aluminum alloy produced at a temperature of 700 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the TP-1 method.

[0107] FIG. 14C shows the grain structure of a 1350 aluminum alloy produced at a temperature of 725 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the Opticast method.

[0108] FIG. 14D shows the grain structure of a 1350 aluminum alloy produced at a temperature of 725 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the TP-1 method.

[0109] FIG. 14E shows the grain structure of a 1350 aluminum alloy produced at a temperature of 750 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the Opticast method.

[0110] FIG. 14F shows the grain structure of a 1350 aluminum alloy produced at a temperature of 750 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the TP-1 method.

[0111] FIG. 14G shows the grain structure of a 1350 aluminum alloy produced at a temperature of 775 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the Opticast method.

[0112] FIG. 14H shows the grain structure of a 1350 aluminum alloy produced at a temperature of 775 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the TP-1 method.

[0113] FIG. 141 shows the grain structure of a 1350 aluminum alloy produced ata temperature of 800 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the Opticast method.

[0114] FIG. 14J shows the grain structure of a 1350 aluminum alloy produced at a temperature of 800 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the TP-1 method.

[0115] FIG. 14K shows the grain structure of a 1350 aluminum alloy produced at a temperature of 825 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the Opticast method.

[0116] FIG. 14L shows the grain structure of a 1350 aluminum alloy produced at a temperature of 825 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the TP-1 method.

[0117] FIG. 14M shows the grain structure of a 1350 aluminum alloy produced at a temperature of 850 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the Opticast method.

[0118] FIG. 14N shows the grain structure of a 1350 aluminum alloy produced at a temperature of 850 °C with an addition of 300 ppm B and 200 ppm Ca, after Poulton attack based on the TP-1 method.

[0119] FIG. 15A shows the grain structure of the base alloy of Table 4 following the TP-1 method.

[0120] FIG. 15B shows the grain structure of the alloy X of Table 4 following the TP-1 method 10 mins after Ca addition.

[0121] FIG. 15C shows the grain structure of the alloy X of Table 4 following the TP-1 method 60 mins after Ca addition.

[0122] FIG. 15D shows the grain structure of the alloy Y of Table 4 following the TP-1 method 10 mins after Ca addition.

[0123] FIG. 15E shows the grain structure of the alloy Y of Table 4 following the TP-1 method 60 mins after Ca addition.

[0124] FIG. 16 is a photograph of the high pressure vacuum die casting (HPVDC) plate used in Example 7.

[0125] FIG. 17A shows the microstructure by optical emission spectrometer (OES) of the HPVDC base alloy of Table 5.

[0126] FIG. 17B shows the microstructure by OES at the center of the HPVDC base alloy of table 5.

[0127] FIG. 17C shows the microstructure by OES of the HPVDC alloy 1 of Table 5.

[0128] FIG. 17D shows the microstructure by OES at the center of the HPVDC alloy 1 of Table 5.

[0129] FIG. 17E shows the microstructure by OES of the HPVDC alloy 2 of Table 5.

[0130] FIG. 17F shows the microstructure by OES at the center of the HPVDC alloy 2 of Table 5.DETAILED DESCRIPTION

[0131] It was surprisingly found that the combination of boron and calcium created an effective grain refiner for aluminum alloys. Specifically, the addition of B and Ca formed CaBe particles which are an effective grain refiner. CaB6particles provide nucleation sites for aluminum grains, resulting in a finer grain structure. The advantage of B and Ca as a replacement to Ti is that B and Ca do not have any significant negative effect on the properties of the alloys. Indeed, unlike TiB2 or TiC, both B and Ca do not negatively affect the electrical conductivity of the alloy. Another advantage of the present calcium boron grain refiner is that the use of boron and calcium is more cost-effective compared to traditional grain refiners. This makes the boron and calcium grain refiner an advantageous alternative over traditional titanium based grain refiners even for non-conductive aluminum alloys. In the context of foundry alloys, the present grain refiner has an advantage of reduced or no settling of the grain refiner and a reduction in hot tearing. In the context of electrical alloys produced by a continuous Properzi casting, the present grain refiner also has the advantage of maintaining a uniform heat transfer and a higher casting speed.

[0132] The Ca and B can be added in the molten aluminum, prior to solidification, to combine and form calcium hexaboride (CaBe) which acts as the grain refiner. The CaBe particles have a density very close to that of molten aluminum, which limit or preferably prevent settling which would have resulted in a loss of grain refining effect over time. Additionally, it was presently found that the presence of calcium conveniently enhances the interfacial heat transfer coefficient between the mould and the metal during solidification, leading to improved casting speeds and thus reduced production costs. The present grain refiner can maintain its efficiency even if the metal is solidified and remelted. The presence of calcium was also found to improve heat transfer by making the heat transfer less variable which can eliminate hot and cold spots on the product or part produced. The presence of hot and colds spot lead to hot tears, which is an undesirable defect that may cause severe production issues. Accordingly, the presence of calcium leads to better solidification and reduced defects.

[0133] Accordingly, the present disclosure provides an aluminum alloy with an addition of boron and calcium as a grain refiner. In some embodiments, the aluminum alloy is an electrically conducting aluminum alloy. Boron is provided in a content of from 100 to 500 ppm. It was found that at least 100 ppm of boron was needed to obtain the grain refiner effect. The maximum content of boron is 500 ppm because above this amount the solubility of the alloy becomes unmanageable. Calcium is provided in excess as a concentration of up to 0.1 wt. % or up to 1000ppm. Excess Ca in the Ca-B addition can be used to help modify the eutectic phase in Al-Si alloys. A minimum content of more than 69 ppm such as 70 ppm or 100 ppm was found to be sufficient to provide the grain refining effect. In at least some embodiments, calcium is provided in a content of from 70 to 1000 ppm, from 100 to 1000 ppm, from 70 to 800 ppm, from 70 to 600 ppm, from 70 to 500 ppm, from 70 to 400 ppm, from 70 to 300 ppm, from 100 to 1000 ppm, from 100 to 800 ppm, from 100 to 500 ppm, from 100 to 400 ppm or from 100 to 300 ppm. In at least some embodiments, boron is present in a content of from 100 to 400 ppm, from 100 to 350 ppm, from 150 to 350 ppm, or from 200 to 300 ppm. In at least some preferred embodiments, the calcium is present in a content of from 100 to 300 ppm, from 100 to 250 ppm, from 150 to 250 ppm, or from 175 to 225 ppm. Since Ca and B form CaBe, the Ca and B can be provided in a concentration such that the atomic ratio of B to Ca is from 5.5:1 to 6.5:1, from 5.75:1 to 6.25:1 from 5.8:1 to 6.2:1, from 5.9:1 to 6.1 or is about 6:1 where about is defined as ±5% in the present disclosure unless stated otherwise. In at least some embodiments, the B and Ca are present in a weight ratio of Ca:B of from 1:3 to 1.3:1 or from about 1:3 to about 1:1. In one particular example, boron and calcium are provided in a concentration of about 300 ppm and about 200 ppm respectively which corresponds to the atomic ratio of Ca:B is 1:6. Although it is preferred to provide Ca and B in the atomic ratio of 1:6 to form CaBe, deviation from the ratio are acceptable and does not have any detrimental impact on the electrical conductivity. Specifically, any excess of Ca or B in the aluminum does not significantly reduce the electrical conductivity of the alloy. This tolerance for excess of Ca or B is an advantage over traditional titanium grain refiners. In the traditional alloys, the extra boron poisons the traditional grain refiner because a layer of AhTi cannot form on the surface of the TiC or TiB2 particles to activate nucleation. Furthermore, as explained above, the addition of excess boron can be beneficial in removing impurities that negatively affect the electrical conductivity of the alloy.

[0134] The grain refiner of the present disclosure is compatible with any process of producing aluminum alloys that involves obtaining a molten intermediate of the alloy. For example, the present grain refiner can be utilized in the Properzi process used to produce aluminum conductor alloys. In the exemplary embodiment where a part is produced by the Properzi process, boron can be added to the molten aluminum in the furnace. Calcium can be added either in the furnace or in-line using a rod feeder. These elements react to form CaBe, which serves as a grain refiner. More generally, there is provided of preparing an aluminum electrically conductive part by melting the aluminum alloy as described in the present disclosure and adding boron and calcium in the concentration described herein before solidification. Then, allowing the molten aluminum alloy tocool and solidify thereby producing the aluminum electrically conductive part. The process contemplated herein is completely free of any Ti based grain refiner addition such as TiB2 or TiC. The temperature of the molten aluminum alloy can be lower than high temperature processes, and is for example less than 800 °C or from 700 to 800 °C.

[0135] The grain refiner described herein is applicable to aluminum alloys such as Al-Si foundry alloys and aluminum conductor alloys. The aluminum conductor alloys are for example those of the 1xxx, 3xxx, 4xxxx, 5xxx, 6xxx and 8xxx series. The composition of the alloys contemplated herein is nevertheless described below in further detail.

[0136] The aluminum alloy of the present disclosure comprises iron in a concentration of up to wt. 2 %. Iron can be a beneficial optional addition to provide desirable high die soldering resistance to extend the die life. The presence of iron provides the alloy with low chemical attachment on steel moulds during casting processes which reduces die soldering and improves castability. The content of iron is provided in a maximum of 2.0 wt. % because above that concentration, the iron would not dissolve sufficiently in the molten aluminum. In some embodiments, the iron is provided in a concentration of up to 1.9 wt. %, up to 1.8 wt. %, up to 1.7 wt. %, up to 1.6 wt. %, up to 1.5 wt. %, up to 1.0 wt. %, up to 0.75 wt. %, up to 0.5 wt. % or up to 0.4 wt. %. In at least some embodiments, the iron is a deliberate addition in the alloy and is provided in a concentration of 0.05 wt. %or more, of 0.06 wt. %or more, 0.08 wt. %or more or of 0.1 wt. % or more.

[0137] The aluminum alloy of the present disclosure comprises silicon in a concentration of up to 12 wt. %, up to 11 wt. %, up to 10 wt. %, up to 9 wt. %, up to 8 wt. %, up to 7 wt. %, up to 6.5 wt. %, up to 6 wt. %, up to 5.5 wt. % or up to 5.0 wt. %. Accordingly, in some embodiments the aluminum alloy of the present disclosure is an Al-Si alloys. However, the addition of Si reacts with Fe to form hexagonal shaped AI8Fe2Si phase. The hot tearing resistance of the alloy tends to decrease due to Si. For this reason, in some embodiments, Si is only provided in small concentrations of up to 1.5 wt. %, up to 1.0 wt. %, up to 0.5 wt. %, and preferably in the context of a conductive aluminum alloy up to 0.3 wt. %, up to 0.25 wt. %, up to 0.2 wt. %, up to 0.15 %, up to 0.1 wt. %.

[0138] Unlike traditional alloys which contain a deliberate addition of Ti as part of the grain refiner, Ti can be present in the aluminum alloy of the present disclosure, but only as an impurity. When present, the weight percentage of Ti in the aluminum alloy of the present disclosure (beforeand after grain refiner addition) is less than about 0.05 wt. %, less than about 0.04 wt. %, less than about 0.03 wt. %, less than about 0.02 wt. %, less than about 0.01 wt. %, less than about 0.005 wt. % or less than about 0.001 wt. %. As previously explained, the absence of Ti as an alloying element or as a grain refiner is a significant advantage of the present alloy since Ti negatively affects the electrical conductivity. In preferred embodiments where the present aluminum alloy is an electrical aluminum alloy, the concentration of Ti is less than about 0.01 wt. %, less than about 0.005 wt. % or less than about 0.001 wt. %.

[0139] In at least some embodiments, Mg can be present in the aluminum alloy of the present disclosure, in a concentration of up to 1.5 wt. %, up to 1.25 wt. %, up to 1.0 wt. %, up to 0.75 wt. %, up to 0.6 wt. %, up to 0.5 wt. %, up to 0.4 wt. %, up to 0.3 wt. %, up to 0.2 wt. % or up to 0.1 wt. %. In at least some embodiments, when the aluminum alloy of the present disclosure is a foundry aluminum alloy, Mg can be provided in a concentration of at least 0.1 wt. % so as to form precipitates with Si. In at least some embodiments, Mg may not be a deliberate addition to the aluminum alloy of the present disclosure and is thus an impurity. Indeed, Mg can increase the susceptibility of the alloy to hot tearing. In embodiments where Mg is considered an impurity, the weight percentage of Mg is less than about 0.05 wt. %, less than about 0.04 wt. %, less than about 0.03 wt. %, less than about 0.02 wt. % or less than about 0.01 wt. %.

[0140] In at least some embodiments, Zr can be present in the aluminum alloy of the present disclosure, in a concentration of up to 0.15 wt. %, up to 0.10 wt. %, or up to 0.05 wt. %. In at least some embodiments, when the aluminum alloy of the present disclosure is an electrical aluminum alloy, there is no deliberate addition of Zr and Zr is an impurity. This is because the Zr can have a negative effect on the electrical conductivity of the alloy. When present, the weight percentage of Zr in the electrical aluminum alloy of the present disclosure is less than about 0.05 wt. %, less than about 0.04 wt. %, less than about 0.03 wt. %, less than about 0.02 wt. % or less than about 0.01 wt. %. It should also be noted that Zr is beneficial for alloys destined for high temperature applications. When these alloys are heat treated, Zr precipitates in the form of AIZra and the conductivity increases during that step.

[0141] In at least some embodiments, Mn can be present in the aluminum alloy of the present disclosure, in a concentration of up to 1.5 wt. %, up to 1.25 wt. %, up to 1.0 wt. %, up to 0.75 wt. %, up to 0.65 wt. %, up to 0.6 wt. %, up to 0.5 wt. %, up to 0.4 wt. %, up to 0.3 wt. %, up to 0.2 wt. % or up to 0.1 wt. %. In at least some embodiments, there is no deliberate addition of Mn and Mn is an impurity. This is because can have Mn a negative effect on the electrical conductivity ofthe alloy. When present as an impurity, the weight percentage of Mn in the aluminum alloy of the present disclosure is less than about 0.05 wt. %, less than about 0.04 wt. %, less than about 0.03 wt. %, less than about 0.02 wt. % or less than about 0.01 wt. %.

[0142] In at least some embodiments, Cr can be present in the aluminum alloy of the present disclosure, but only as an impurity. This is because the Cr has a negative effect on the electrical conductivity of the alloy. In the context of the present disclosure, Cr is not a deliberate addition to the aluminum alloy of the present disclosure. When present, the weight percentage of Cr in the aluminum alloy of the present disclosure is less than about 0.05 wt. %, less than about 0.04 wt. %, less than about 0.03 wt. %, less than about 0.02 wt. % or less than about 0.01 wt. %.

[0143] In at least some embodiments, V can be present in the aluminum alloy of the present disclosure, but only as an impurity. This is because the V has a negative effect on the electrical conductivity of the alloy. In the context of the present disclosure, V is not a deliberate addition to the aluminum alloy of the present disclosure. When present, the weight percentage of V in the aluminum alloy of the present disclosure is less than about 0.05 wt. %, less than about 0.04 wt. %, less than about 0.03 wt. %, less than about 0.02 wt. % or less than about 0.01 wt. %.

[0144] In at least some embodiments, when the aluminum alloy of the present disclosure is an electrical aluminum alloy, the total impurity amount of Ti+Cr+Mn+V is less than 0.05 wt. %, preferably less than 0.025 wt. %. These impurities negatively affect the conductivity of the alloy and they are treated by providing an excess of B (e.g. up to 500 ppm). The present grain refiner is thus particularly advantageous for electrical aluminum alloys that require boron treatment of impurities since the boron is leveraged thanks to the calcium as a grain refiner.

[0145] In at least some embodiments, Sr can be present in the aluminum alloy of the present disclosure, but only as an impurity. As demonstrated in Example 1 below, the addition of Sr did not provide any benefit as a grain refiner. Accordingly, the deliberate addition of Sr in an amount of up to 300 ppm is optional. Generally, Sr is an impurity in the present aluminum alloy and is present in a concentration of less than about 0.05 wt. %, less than about 0.04 wt. %, less than about 0.03 wt. %, less than about 0.02 wt. % or less than about 0.01 wt. %. Since Sr could be competing with Ca for the formation of particles with B, it is preferred that no deliberate Sr addition is made. It should be noted that boron has a higher affinity with calcium. The advantage of Ca is that its molar mass is lower than Sr which means the addition required Ca is lass than Sr. Calcium also gives a more constant recovery than strontium, and the density of the reaction product, CaBe,is 2.4g / cm3, equivalent to that of liquid aluminum which is an advantage in avoiding settling and avoiding loss of grain refiner.

[0146] In at least some embodiments, Ni can be present in the aluminum alloy of the present disclosure, in a concentration of up to 6 wt. %, up to 5 wt. %, up to 4 wt. %, up to 2 wt. %, up to 1 wt. %, or up to 0.5 wt. %. In at least some embodiments, there is no deliberate addition of Ni and Ni is an impurity. This is because Ni can have a negative impact on the corrosion resistance of the alloy. When present as an impurity, the weight percentage of Ni in the aluminum alloy of the present disclosure is less than about 0.05 wt. %, less than about 0.04 wt. %, less than about 0.03 wt. %, less than about 0.02 wt. % or less than about 0.01 wt. %.

[0147] In at least some embodiments, Cu can be present in the aluminum alloy of the present disclosure, in a concentration of up to 0.3 wt. %, up to 0.25 wt. %, up to 0.2 wt. %, up to 0.15 wt. %, or up to 0.1 wt. %. Cu is part of the 8xxx alloy compositions and provides an increase in strength with a small or minimal impact on the electrical conductivity. In at least some embodiments, there is no deliberate addition of Cu and Cu is an impurity. When present as an impurity, the weight percentage of Cu in the aluminum alloy of the present disclosure is less than about 0.05 wt. %, less than about 0.04 wt. %, less than about 0.03 wt. %, less than about 0.02 wt. % or less than about 0.01 wt. %.

[0148] In at least some embodiments, the impurities in the aluminum alloy of the present disclosure can include one or more of Ce, Zn, Be, Bi, Ga, Ni, Pb, P, Co, Sn, each in a concentration of less than 0.01 wt. %. In particular, Be is harmful for the health of workers who handle the alloys and P can poison the modification of Ca and Si on the Al-Si eutectic phase. Accordingly, in preferred embodiments, Be and P are both present in a concentration of less than 0.005 wt. % or less than 0.001 wt. %.

[0149] In at least some embodiments, the total concentration of impurities is less than 0.3 wt. %, less than 0.25 wt. %, preferably less than 0.2 wt. %, more preferably less than 0.15 wt. %.

[0150] The aluminum alloy of the present disclosure can be an AA1350 alloy having a composition in weight percentage of 0.05 - 0.10 Si, up to 0.4 Fe such as from 0.05 to 0.4 or 0.05 to 0.15, equal to or less than 0.05 of Cu, Mn, Zn, equal to or less than 0.01 Cr and less than 0.03 of other elements (may be as detailed above) along with the B and Ca additions in the concentration ranges detailed above.

[0151] The present aluminum alloy (e.g. as an AA1350 alloy) is particularly useful in power line applications, such as electrical cables. The aluminum alloy can be used to produce high conductivity aluminum rod that are an improvement over the traditional AA1350 alloys, for example by having an improved electrical conductivity while maintaining similar mechanical properties. On projects such as large scale electrical cable connections, improvements as little as 1% or even lower in terms of IACS conductivity translates to massive cost savings.

[0152] The present aluminum alloy is also particularly useful as rotor alloys for electrical car applications. The rotor aluminum alloy may comprise in weight percentage 0.10 - 0.15 Si, 1.3 -1.7 Fe, 1.5 - 1.8 Ni, and less than 0.03 of other elements (may be as detailed above) along with the B and Ca additions in the concentration ranges detailed above.EXAMPLE 1

[0153] In the quest of finding an alternative to titanium boron grain refiners, Sr was tested as a replacement to titanium. Two identical bars were produced with an AA1188 alloy (see Table 1). When forming the control bar, an addition of 400 ppm of B was made, whereas when forming the second bar, additions of 400 ppm of B and 200 ppm of Sr were made.Table 1. Composition of the alloys tested for Sr as grain refiner

[0154] As shown in Figs. 1A-1H the surface of the control bar and the second bar which had the addition of Sr was the same. Moreover, the cooling zones and the grain size was identical in both cases (Figs. 2A-2D). Furthermore, the presence of a sporadic worm hole was identified in both bars (Figs. 3A-3B). The presence of B-Sr-AI phases was identified in both bars (Figs. 4A-4G). Thus, the addition of Sr did not have any effect as a grain refiner and the search for an alternative to Ti continued.EXAMPLE 2

[0155] An alloy comprising 0.05 wt. % Si and 0.10 wt. % Fe was selected to test various compositions of grain refiners. The alloys were tested according to TP-1 the standard test procedure for aluminum alloy grain refiners of the Aluminum Association. The additions tested were 300 ppm of B (Fig. 5A), 300 ppm of B and 200 ppm of Ca (Fig. 5B), stoichiometric B (Fig.5C), stoichiometric B and 0.2 wt. % TiC (Fig. 5D), 300 ppm of B and 400 ppm of Sr (Fig. 5E), 400 ppm of B and 0.8 wt. % TiC (Fig. 5F), 500 ppm of B and 1.6 wt. % TiC (Fig. 5G), and 600 ppm of B and 2.4 wt. % TiC (Fig. 5H). As can be seen from Figs. 5A-5H, the addition of 300 ppm of B and 200 ppm of Ca (Fig. 5B) provided the best grain refining and the finest grain structure.EXAMPLE 3

[0156] Based on the findings in Example 2 on the performance of B and Ca as grain refiners, the concentrations of B and Ca were further investigated. An alloy comprising 0.05 wt. % Si and 0.10 wt. % Fe was tested according to TP-1 and also according to the Opticast method. For both TP-1 and Opticast, the grain structure was observed with the base alloy composition (Figs. 6A and 7A), an addition of 300 ppm B (Figs. 6B and 7B), an addition of 300 ppm B and 50 ppm Ca (Figs. 6C and 7C), an addition of 300 ppm B and 100 ppm Ca (Figs. 6D and 7D), an addition of 300 ppm B and 150 ppm Ca (Figs. 6E and 7E), an addition of 300 ppm B and 200 ppm Ca (Figs.6F and 7F), an addition of 300 ppm B and 250 ppm Ca (Figs. 6G and 7G), and an addition of 300 ppm B and 300 ppm Ca (Figs. 6H and 7H). As can be seen from the figures, all the additions of B and Ca were satisfactory except the addition of 50 ppm of Ca which was too low. Accordingly, there is significant flexibility possible in varying the ratio of B and Ca while still obtaining a desirable grain refining effect (see also Table 2).

[0157] The grain structure was measured by electron backscatter diffraction (EBSD) is presented in Table 2. For EBSD, the area of the surface analyzed was about 8.5 mm2, the step size was 8 pm and the threshold was 15°.Table 2. Grain structure of the alloy with various additions>>EXAMPLE 4

[0158] The alloy sample with the addition of 300 ppm B and 200 ppm Ca of Example 3 was selected for further analysis by optical microscopy and energy dispersive X-ray spectroscopy (EDS). Using a Keyence VHX-7000 microscope, the presence of CaBe particles was investigated (Figs. 8A-8C). The average particle size observed was between 5 and 6 pm with a maximum size of 8.6 pm and a minimum of 2.5 pm.

[0159] The EDS analysis (Figs. 9A-9B) confirmed that the particles observed are indeed CaBe particles. The theoretical contents of a pure CaBe particle is 38.2% of Ca and 61.8 % of B by weight percentage. As shown in Fig. 9B and table 3, the particle analyzed was in fact a CaBe particle.Table 3. EDS element analysis of Fig. 9B

[0160] The contents of the CaBe particles were further confirmed by a line scan and element analysis along that line (Figs. 10A-10B and 11A-11B). As can be seen in Figs. 10B and 11B, the contents of Al are near 100% at the matrix and drastically fall as the line reaches the particle and then drastically rise back to close to 100% after the line crosses the particle.EXAMPLE 5

[0161] A different alloy composition, namely a 1350 aluminum alloy comprising 0.05 wt. % Si and 0.10 wt. % Fe was tested according to TP-1 and also according to the Opticast method as described above. The same 1350 aluminum alloy composition was used at temperatures of 700 °C, 725 °C, 750 °C, 775 °C, 800 °C, 825 °C, and 825 °C. At each temperature, a stoichiometric B content was added (B = Ti / 2 + V / 2, atomic ratio) (Figs. 12A-12N), 300 ppm of B was added as grain refiner (Figs. 13A-13N), and 300 ppm of B and 200 ppm of Ca were added as grain refiner (Figs. 14A-14N). As can be seen from Figs. 12A-12N, 13A-13N, and 14A-14N, the combination of Ca and B as grain refiners, even when B is provided in excess, was an effective grain refiner and reduced grain size. Furthermore, the addition of excess B is preferred for electrical aluminum alloys since this excess of B is used to eliminate the V, Zr and Ti impurities.EXAMPLE 6

[0162] Al-Fe-Ni rotor alloys were tested under TP-1 “Standard Test Procedure for Aluminum Alloy Grain Refiners”, Aluminum Association, (2012). The composition of the alloys tested are presented in the table below.Table 4. Rotor alloy chemistry tested

[0163] The TP-1 results are presented in Figs. 15A through 15E. No grain refinement was obtained with only boron addition, as seen in the base alloy (Fig. 15A). The addition of 224 ppm boron and 69 ppm calcium in alloy X was not sufficient to refine the grains (Figs. 15B-15C) indicating a cut off at less than 70 ppm for Ca for the case of the rotor alloy composition. Excellent grain refining was obtained in alloy Y (Figs. 15D-15E) which demonstrates that a concentration of 373 ppm boron combined with 230 ppm calcium is sufficient to grain refine the alloy.EXAMPLE 7

[0164] The grain-refining test Example 6 provided desirable results to improve the alloy properties. To quantify the impact on the mechanical and electrical properties, 3 mm thick diecast plates were produced on CMQ’s Buhler 250 t high-pressure vacuum die-casting (HPVDC) press as shown in Fig. 16. Three levels of boron and calcium were tested to validate the impact of CaBe grain refinement. The targeted boron contents were 300 ppm and 500 ppm. The chemical compositions of the alloys are presented in Table 2. The microstructures obtained are shown in Figs. 17A-17F.Table 5. Chemical composition cast<<<* Analysis discrepancy between two analysis, the second gave a B content of 358 ppm and a calcium content of 220 ppm

[0165] When examining the individual sparks taken on the optical emission spectrometer (OES) sample, the boron and calcium contents varied greatly between two different test centers. This may be attributed to the formation of CaB6. Calcium and boron form particles that are non-homogeneous in the OES sample, which increases the variation from spark to spark. It is therefore difficult to analyze their concentrations precisely. Nonetheless, similar trends in the microstructure are observed in the die-cast plates as in the TP-1 samples of Example 6. At 500 ppm boron, for alloy HPVDC 2 (Table 5), the concentration of boron and calcium eliminated the externally solidified crystals (ESC). The ESC content is typically linked to molten metal or shot sleeve temperature; however, these parameters were kept constant (Table 6). A lower porosity content was also observed in Figs. 17E-17F. However, due to the high solidification rate during high-pressure vacuum die-casting, no clear grain size or aluminium dendrite size reduction is visible. From the mechanical properties presented in Table 7, the reduction in ESC and porosity increased the ductility of alloy HPVDC 2.Table 6. Die-casting process parametersHPVDC base between 9:48 and 10:20, HPVDC alloy 1 between 11:33 and 12:04, and HPVDC alloy 2 between 14:38 and 15:14.Table 7. Mechanical properties and electrical conductivity of die-cast parts

[0166] Both alloys HPVDC 1 and HPVDC 2 give statistically higher electrical conductivity than the base alloy. The addition of excess boron and calcium improved the integrity of the cast part by lowering the ESC and porosity content. The increased integrity significantly improved the elongation of alloy HPVDC 2 from 16.4% to 19.0%.

Claims

WHAT IS CLAIMED IS:

1. An aluminum alloy, comprising:up to 2.0 wt. % of Fe;up to 12 wt. % of Si;up to 1.5 wt. % Mg;up to 1.5 wt. % Mn;up to 0.15 wt. % Zr;up to 6 wt. % of Ni;up to 0.3 wt. % of Cu;from 100 to 500 ppm of B;from 70 to 1000 ppm of Ca; andup to 0.3 wt. % of impurities;wherein the balance is aluminium.

2. The aluminum alloy of claim 1, wherein the aluminum alloy comprises less than 0.05 wt.% of Zr.

3. The aluminum alloy of claim 1 or 2, wherein the impurities comprise less than 0.05 wt. % of V.

4. The aluminum alloy of any one of claims 1 to 3, wherein the aluminum alloy comprises less than 0.05 wt. % of Mg.

5. The aluminum alloy of any one of claims 1 to 4, wherein the aluminum alloy comprises less than 0.05 wt. % of Cu.

6. The aluminum alloy of any one of claims 1 to 5, wherein the impurities comprise less than 0.01 wt. % of Ti.

7. The aluminum alloy of any one of claims 1 to 6, wherein the impurities comprise less than 0.05 wt. % of Sr.

8. The aluminum alloy of any one of claims 1 to 7, wherein the impurities comprise one or more of Ce, Zn, Be, Bi, Ga, Ni, Pb, P, Co, and Sn, each in a concentration of less than 0.01 wt. %.

9. The aluminum alloy of any one of claims 1 to 8, wherein B is present in a concentration of from 100 to 400 ppm.

10. The aluminum alloy of any one of claims 1 to 9, wherein Ca is present in a concentration of from 100 to 300 ppm.

11. The aluminum alloy of any one of claims 1 to 10, wherein B and Ca are present in a weight ratio of Ca:B of from 1:3 to 1.3:1.

12. The aluminum alloy of any one of claims 1 to 11, wherein B and Ca are present in an atomic ratio of Ca:B of from 5.5:1 to 6.5:1.

13. The aluminum alloy of any one of claims 1 to 12, wherein B and Ca are present in an atomic ratio of Ca:B of 1:6 ±5%.

14. An electrical aluminum alloy, comprising:up to 2.0 wt. % of Fe;up to 0.3 wt. % of Si;from 100 to 500 ppm of B;from 70 to 1000 ppm of Ca; andup to 0.3 wt. % of impurities;wherein the balance is aluminium.

15. The electrical aluminum alloy of claim 14, wherein the impurities comprise less than 0.01 wt. % of Ti.

16. The electrical aluminum alloy of claim 14 or 15, wherein the impurities comprises Ti, Cr, Mn, V and the total of Ti, Cr, Mn, V is less than 0.05 wt. %.

17. The electrical aluminum alloy of any one of claims 14 to 16, wherein B and Ca are present in a weight ratio of Ca:B of from 1:3 to 1.3:1.

18. A process of making aluminum part, the process comprising:melting an aluminum alloy comprising up to 2.0 wt. % of Fe; up to 0.6 wt. % Mg, up to 0.65 wt. % Mn, up to 0.15 wt. % Zr and up to 10 wt. % of Si to obtain a molten alloy;adding to the molten alloy from 100 to 500 ppm of B and from 70 to 300 ppm of Ca; andsolidifying the molten alloy to obtain the aluminum part.

19. The process of claim 18, wherein the process is a Properzi process.

20. The process of claim 18, wherein the process is a foundry casting process.

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