Brazable cast aluminum alloys

Abstract

An aluminum alloy composition having high electrical conductivity is provided. A low electrical conductivity base material is also described.

Description

[Technical field]

[0001] [Cross-filing of related applications] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 203,476, filed July 23, 2021, which is incorporated by reference in its entirety herein. [Background technology]

[0002] In general, brazing is a metal joining process in which two or more metal articles are joined together by melting and flowing a braze metal into the joint. Typically, the brazing process uses a braze metal with a lower melting point than the adjacent metals to attempt to avoid melting the joined metal articles. The braze metal flows into the gap between the joints by capillary action. The braze metal is brought to a temperature slightly above its melting point while protected by a suitable atmosphere. The liquid braze material then flows over the base metal and is then cooled to join the two metal pieces together.

[0003] In the context of joining aluminum pieces, the use of brazing can reduce leakage of flow passages between the pieces, facilitate high temperature operating joints compared to adhesive bonding, small detailed parts with intricate joints, large contact area for strong joints, and electrical connection between the metal pieces. Aluminum is generally characterized as having a low melting point, consistent and stable oxides, high thermal conductivity, high thermal expansion, and low density. Therefore, aluminum pieces are typically brazed with some aluminum-based braze alloys that are characterized by a lower melting point to enable the brazing process. [Brief description of the drawings]

[0004] [Figure 1] 1 is an exemplary graph of a high thermal conductivity matrix for a cast alloy system;

[0005] [Diagram 2] 1 is a chart of suitable low conductivity host materials having eutectic / peritectic temperatures above 600° C. Detailed Description of the Invention

[0006] The present invention relates to an aluminum alloy. More specifically, the present invention relates to an aluminum alloy having relatively high strength, good castability and improved brazing for high performance applications, including automotive parts. One or more aspects of the present application relate to an embodiment in which the alloy exhibits low thermal conductivity. One or more aspects of the present application may further relate to other embodiments in which the alloy exhibits high thermal conductivity. Illustratively, the alloy corresponds to an aluminum alloy. The present disclosure may be understood by reference to the following detailed description in conjunction with the drawings described below. It should be noted that for clarity of illustration, certain elements in the various drawings may not be drawn to scale, may be represented diagrammatically or conceptually, and may not otherwise precisely correspond to a particular physical configuration of an embodiment.

[0007] The embodiments relate to aluminum alloys that are useful for making products. Aluminum castings generally have a low melting point, similar to that of the brazing filler metal used for brazing. Therefore, brazing aluminum castings is extremely difficult or impossible with traditional brazing techniques, as the base metal is often subject to melting or erosion. For example, in some embodiments, an aluminum base metal can be brazed with an aluminum brazing filler metal. However, most brazing filler metals are from the same low melting point system as the most common casting alloys (Al-Si or Al-Mg). This means that most aluminum castings are not considered brazable, as the base metal melts during the brazing process.

[0008] In the context of vehicles and vehicle manufacturing, for example, in certain HVAC applications where hot and cold lines are in close proximity to each other, thermal conductivity is undesirable as it can cause parasitic heat losses in the system. Therefore, when casting such HVAC components, they should be constructed from alloys / materials that have low conductivity, excellent castability, and the ability to exhibit good brazeability. Some materials, such as U.S. Patent Application Publication No. 2019 / 0127824, entitled "CASTING ALUMINUM ALLOYS FOR HIGH-PERFORMANCE APPLICATIONS," have good castability and also exhibit excellent conductivity. U.S. Patent Application Publication No. 2019 / 0127824 is incorporated herein by reference. In another example, a material such as an aluminum alloy called 6063 (magnesium and silicon) is commonly used in manufacturing, but does not exhibit optimal conductivity or castability. Other applications in vehicles that may be applicable with brazed aluminum pieces for high conductivity applications in vehicles may include bus bars, heat sinks / cold plates and other piping or pressure vessels.

[0009] Current techniques for brazing filler materials allow for brazing of conventional aluminum castings, but these materials tend to be available in limited geometries. As previously mentioned, many typical brazing materials are not well suited for use in conventional high volume brazing processes with aluminum castings, as the base metal has a melting point similar to the typical brazing material. FIG. 1 shows plots of thermal conductivity versus solidus temperature for several alloy systems, such as cast alloys and wrought alloys. In one embodiment shown in FIG. 1, a range of temperatures used for brazing is shown, ranging from approximately 585°C to 610°C, to identify alloy systems that have solidus temperatures below the brazing range (e.g., Al-Si cast) and alloy systems that have solidus temperatures above the brazing range (e.g., 3000 series forging). In some embodiments, the high temperature solid solution materials of the present disclosure can have solidus temperatures greater than 610°C, 620°C, 630°C, 640°C, 650°C, or 660°C. In other embodiments, the high conductivity host material of the present disclosure can have a solidus temperature greater than 630° C., 640° C., or 650° C. In another aspect shown in FIG. 1, the alloy system can have a variety of heat transfer properties.

[0010] One or more aspects of the present application correspond to a brazing base material comprising a high melting point casting alloy exhibiting properties corresponding to excellent castability. More specifically, the brazing base material is configured to be brazed with a conventional brazing process, including, but not limited to, vacuum brazing, controlled atmosphere brazing (CAB) brazing, and induction brazing, which are typically only applicable to wrought aluminum alloy base materials. In one aspect, the brazing base material is illustratively characterized by a high solidus temperature compared to other brazing materials, including, but not limited to, Al-Si or Al-Mg brazing materials. In another aspect, the brazing base material can be characterized based on thermal conductivity properties. In one aspect, the characterization of low or lower thermal conductivity can be based on a thermal conductivity property of 100 W / mK or less. In some embodiments, the characterization of high or higher thermal conductivity can be based on a thermal conductivity property of about 160-220 W / mK. In another aspect, the characterization of high or higher thermal conductivity can be based on a thermal conductivity property of 170-200 W / mK. Those skilled in the art will appreciate that the thermal conductivity ranges are exemplary in nature and do not represent all possible characteristics of thermal conductivity or ranges of values ​​that satisfy the thermal conduction properties. For example, characterization of a low or lower thermal conduction property may be further characterized by various subranges (e.g., 100-80 W / mK), thresholds, or optimum values. In some embodiments, the low conductivity alloys of the present disclosure may have a thermal conductivity in the range of about 80-150 W / mK. In other embodiments, the low conductivity alloys of the present disclosure may have a thermal conductivity in the range of about 90-140 W / mK. Similarly, characterization of a high or higher thermal conduction property may be further characterized by various subranges (e.g., 180-190 W / mK), thresholds, or optimum values. Additionally, the brazed components may be further characterized by other attributes, such as minimum strength.

[0011] Illustratively, for a base material with high conductivity, the base material may correspond to a compound of aluminum, 5.25% nickel, and additional impurities such as iron. An example of a base material with high thermal conductivity is illustratively shown in Figure 1. Such high conductivity base materials in combination with brazing materials may be considered as new applications.

[0012] In another aspect, for low thermal conductivity base materials, the brazeable base material can be made of aluminum combined with at least one high temperature solid solution element based on FCC α-Al matrix. Such low conductivity base materials combined with brazing filler metals may be considered as new alloys. FIG. 2 shows a suitable low conductivity base material with a eutectic / peritectic temperature above 600° C., which is a typical brazing temperature. By way of example, high temperature solid solution materials that can be included in the FCC α-Al matrix include manganese, chromium, titanium, and vanadium, zirconium, iron, nickel, cerium, molybdenum, silicon, copper, magnesium, zinc, or tin, or combinations thereof. In some embodiments, the high temperature solid solution material includes 0.1 wt. %, 0.2 wt. %, or 0.4 wt. % chromium, about these values, at least these values, or at least about these values, or any value range therebetween. In some embodiments, the high temperature solid solution material comprises 0.01 wt%, 0.2 wt%, or 1.3 wt%, titanium, about, at least, or at least about these values, or any value therebetween. In some embodiments, the high temperature solid solution material comprises 0.01 wt%, 0.1 wt%, or 0.65 wt%, vanadium, about, at least, or at least about these values, or any value therebetween. In some embodiments, the high temperature solid solution material comprises 0.3 wt%, 0.5 wt%, or 1 wt%, manganese, about, at least, or at least about these values, or any value therebetween. In some embodiments, the high temperature solid solution material comprises 0.3 wt%, 0.8 wt%, or 1.2 wt%, iron, about, at least, or at least about these values, or any value therebetween. In some embodiments, the high temperature solid solution material comprises 1.5 wt.%, 3 wt.%, 4.5 wt.%, or 6 wt.% nickel, about these values, at least these values, or at least about these values, or any range therebetween.In some embodiments, the high temperature solid solution material comprises 0.01 wt%, 4 wt%, or 8.8 wt%, cerium at about, at least, or at least about, or any value therebetween. In some embodiments, the high temperature solid solution material comprises 0.01 wt%, 0.12 wt%, or 0.15 wt%, magnesium at about, at least, or at least about, or any value therebetween. In some embodiments, the high temperature solid solution material comprises 0.01 wt%, 0.85 wt%, or 1 wt%, zinc at about, at least, or at least about, or any value therebetween. In some embodiments, the high temperature solid solution material comprises 0.01 wt%, 0.85 wt%, or 1 wt%, molybdenum at about, at least, or at least about, or any value therebetween. In some embodiments, the high temperature solid solution material is free or substantially free of silicon, copper, magnesium, zinc, or tin. In some embodiments, the high temperature solid solution material can include elements that readily form supersaturated solid solutions. In some embodiments, the alloy composition can include elements that form dispersoids, such as aluminum alloy 3003. Additionally, the brazeable alloy can include as much iron as necessary to minimize die soldering. Table 1 provides composition ranges for the solution materials. [Table 1]

[0013] Some embodiments of the present invention relate to casting of aluminum alloys having both high yield strength and high thermal conductivity, as well as improved fluidity and resistance to hot tearing or cracking. The aluminum alloys have been found to have high yield strength and high electrical conductivity compared to conventional commercial aluminum alloys. Other embodiments of the present invention relate to casting of aluminum alloys having both high yield strength and low thermal conductivity, as well as improved fluidity and resistance to hot tearing or cracking. The aluminum alloys have also been found to have high yield strength and high electrical conductivity compared to conventional commercial aluminum alloys. Aluminum alloys are described herein by the weight percent (wt%) of all elements and particles within the alloy, as well as the specific properties of the alloy. It is understood that the remaining composition of any alloy described herein is aluminum and incidental impurities.

[0014] Table 2 presents measured properties of high pressure die castings that represent exemplary results of one or more embodiments of the present application. [Table 2]

[0015] In the above specification, the present disclosure has been described with reference to specific embodiments. However, as will be understood by those skilled in the art, the various embodiments disclosed herein can be modified or embodied in various other ways without departing from the spirit and scope of the present disclosure. Accordingly, this description should be considered as illustrative and is for the purpose of teaching those skilled in the art how to make and use the various embodiments of the disclosed systems, methods, and computer program products. It should be understood that the forms of the disclosure shown and described herein should be construed as representative embodiments. Equivalent elements, materials, processes, or steps may be substituted for those typically shown and described herein. Moreover, certain features of the present disclosure may be utilized independently of the use of other features, as will be apparent to those skilled in the art after having the benefit of this description of the present disclosure.

[0016] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," or any contextual variation thereof, are intended to cover non-exclusive inclusions. For example, a process, product, article, or apparatus that includes a list of elements is not necessarily limited to only those elements and may include other elements not expressly listed or inherent to such process, product, article, or apparatus. Furthermore, unless expressly stated otherwise, "or" refers to an inclusive or and not an exclusive or. For example, a condition "A or B" is satisfied by any one of the following: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0017] Although steps, operations, or computations may be presented in a particular order, this order may be changed in different embodiments. In some embodiments, where multiple steps are shown in sequence herein, some combination of such steps in alternative embodiments may be performed simultaneously. A sequence of operations described herein may be interrupted, suspended, reversed, or controlled by another process.

[0018] It will also be understood that one or more of the elements shown in the drawings / diagrams may also be implemented in a more separate or integrated manner, or may be removed or considered inoperative in certain cases, as may be useful depending on the particular application. Additionally, any signal arrows in the drawings / diagrams should be considered as illustrative only and not limiting, unless otherwise noted.

Claims

1. Cr: 0.1 to 0.4% by weight, Mn: 0.3 to 1% by weight, Fe: 0.3 to 1.2% by weight, Ni: containing 1.5 to 6% by weight, with the balance being aluminum and impurities, a high-temperature solution-treated material.

2. The high-temperature solution-treated material according to Claim 1, further containing Ti: 0.01 to 1.3% by weight.

3. The high-temperature solution-treated material according to Claim 1 or 2, further containing V: 0.01 to 0.65% by weight.

4. The high-temperature solution-treated material according to Claim 1 or 2, further containing Ce: 0.01 to 8.8% by weight.

5. The high-temperature solution-treated material according to Claim 1 or 2, further containing Mg: 0.01 to 0.15% by weight.

6. The high-temperature solution-treated material according to Claim 1 or 2, further containing Zn: 0.01 to 1% by weight.

7. The high-temperature solution-treated material according to Claim 1 or 2, further containing Mo: 0.01 to 1% by weight.

8. The high-temperature solution-treated material according to Claim 1 or 2, wherein the high-temperature solution-treated material does not contain or substantially does not contain silicon, copper, magnesium, zinc, or tin.

9. Essentially, consisting of Ni: 4.5 to 6% by weight, with the balance being aluminum and impurities, a high-conductivity base material.

10. The high-conductivity base material according to Claim 9, wherein Ni is 4.75 to 5.75% by weight.

11. The high-conductivity base material according to Claim 10, wherein Ni is 5 to 5.5% by weight.

12. The high-conductivity base material according to Claim 11, wherein Ni is 5.25% by weight.

13. The high-conductivity base material according to any one of Claims 9 to 12, wherein the thermal conductivity is in the range of about 160 to 220 W / mK.

14. The high-conductivity base material according to Claim 13, wherein the thermal conductivity is in the range of about 170 to 200 W / mK.

15. A low-conductivity alloy containing an FCCα - Al matrix, wherein the solidus temperature of the alloy exceeds 610°C and the thermal conductivity is in the range of about 80 to 150 W / mK.

16. The low-conductivity alloy according to Claim 15, wherein the solidus temperature of the alloy exceeds 630°C.

17. The low-conductivity alloy according to Claim 15 or 16, wherein the thermal conductivity is in the range of about 90 to 140 W / mK.

18. The low-conductivity alloy according to Claim 15 or 16, further containing at least one of manganese, chromium, titanium, and vanadium, zirconium, iron, nickel, cerium, or molybdenum.

19. The low-conductivity alloy according to claim 15 or 16, wherein the alloy does not contain or substantially does not contain silicon, copper, magnesium, zinc or tin. **Claim 20** The low-conductivity alloy according to claim 15 or 16, further comprising an element forming a dispersoid.

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