Method and system for high pressure die casting - Patents.com

Abstract

A method and system for high pressure die casting using low silicon content metal alloys is described. The metal alloys can be modified with nanoparticles to achieve high fluidity and hot tear resistance compatible with high pressure die casting. The die cast metal parts have high strength, high ductility, and high thermal and electrical conductivity. The die cast metal parts can be anodized for different colors. The present invention relates generally to a method and system for high pressure die casting using low silicon content metal alloys, and more particularly to a method and system for high pressure die casting using low silicon content metal alloys modified with nanoparticles.

Description

[Technical field]

[0001] FIELD OF THEINVENTION The present invention relates generally to a method and system for high pressure die casting with low silicon content metal alloys, and more particularly to a method and system for high pressure die casting with nanoparticle modified low silicon content metal alloys. [Background technology]

[0002] 2. Background of the Invention Die cast metal alloys have applications in a variety of industries. Die cast metal alloys generally require both high strength and ductility. The metal alloy should also have good castability and thermal crack resistance to be suitable for the high pressure die casting process. Traditionally, silicon has been added to metal alloys such as aluminum alloys to improve the flowability of the metal alloy to be compatible with high pressure die casting. However, high silicon content can deteriorate the ductility, thermal conductivity, electrical conductivity, and anodizing ability of the metal alloy. A metal alloy that is suitable for the high pressure die casting process while not compromising ductility and conductivity may be desirable. Summary of the Invention [Means for solving the problem]

[0003] Summary of the Invention A method and system for high pressure die casting using nanoparticle modified low silicon content metal alloys is illustrated.

[0004] An embodiment of the present invention includes a metal alloy for high pressure die casting comprising a metal alloy selected from the group consisting of an aluminum alloy, a magnesium alloy, a copper alloy, and a zinc alloy, and at least one type of nanoparticles dispersed in the metal alloy, wherein the metal alloy comprises less than 4.0 wt. % silicon, and the metal alloy is compatible with a high pressure die casting process.

[0005] In another embodiment, the metal alloy is selected from the group consisting of A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075, and AA7068.

[0006] In additional embodiments, the at least one type of nanoparticle is selected from the group consisting of a metal oxide, a non-metal oxide, a metal carbide, a non-metal carbide, a metal silicide, a metal boride, a metal nitride, and any combination thereof.

[0007] In a further embodiment, at least one type of nanoparticle has the structure of a core-shell particle.

[0008] In another embodiment, the nanoparticles comprise less than 30% by volume of the metal alloy.

[0009] In still further embodiments, the nanoparticles comprise between 0.1% and 2% by volume of the metal alloy.

[0010] In yet another embodiment, the metal alloy comprises AA6061 and the nanoparticles comprise TiC, wherein the TiC nanoparticles comprise 1.0% by volume of the metal alloy.

[0011] In yet a further embodiment, the high pressure die casting process uses a pressure between 30 MPa and 100 MPa.

[0012] In an additional embodiment, the high pressure die casting process uses a pressure of greater than 100 MPa.

[0013] In yet another embodiment, the high pressure die casting process includes cooling at a cooling rate of 100° C. / s to 300° C. / s.

[0014] A further embodiment is a method for high pressure die casting comprising: providing a metal alloy modified with at least one type of nanoparticle, the metal alloy comprising a silicon weight concentration of less than 4.0%; - melting a metal alloy and filling a die with the molten metal alloy under a pressure, the pressure being compatible with a high pressure die casting process; cooling the die to solidify the molten metal alloy; The present invention includes a method comprising the steps of:

[0015] In yet a further embodiment, the method further comprises anodizing the die-cast metal alloy for at least one color.

[0016] In another embodiment, the metal alloy is selected from the group consisting of an aluminum alloy, a magnesium alloy, a copper alloy, and a zinc alloy.

[0017] In additional embodiments, the metal alloy is selected from the group consisting of A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075, and AA7068.

[0018] In yet another embodiment, the at least one type of nanoparticle is selected from the group consisting of a metal oxide, a non-metal oxide, a metal carbide, a non-metal carbide, a metal silicide, a metal boride, a metal nitride, and any combination thereof.

[0019] In yet a further embodiment, at least one type of nanoparticle has the structure of a core-shell particle.

[0020] In additional embodiments, the at least one type of nanoparticles comprises less than 30% by volume of the metal alloy.

[0021] In yet another embodiment, the nanoparticles comprise between 0.1% and 2% by volume of the metal alloy.

[0022] In a further embodiment, the metal alloy comprises AA6061 and the nanoparticles comprise TiC, wherein the TiC nanoparticles comprise 1.0% by volume of the metal alloy.

[0023] In again another embodiment, the as-formed die cast metal alloy has an elongation less than or equal to 30% and an ultimate tensile strength greater than 500 MPa.

[0024] In yet an additional embodiment, the die cast metal alloy has a thickness of at least 0.2 mm.

[0025] In yet a further embodiment, the pressure is between 30 MPa and 100 MPa.

[0026] In yet another embodiment, the pressure is greater than 100 MPa.

[0027] In another embodiment, the die is cooled at a cooling rate of between 100° C. / s and 300° C. / s.

[0028] In yet a further embodiment, the method further comprises post-processing the die cast metal alloy.

[0029] In an additional embodiment, the post-processing is selected from the group consisting of a T5 treatment, a natural aging treatment, and a T6 treatment.

[0030] Another embodiment includes a high pressure die cast metal part comprising a metal alloy and at least one type of nanoparticles dispersed in the metal alloy, wherein the metal alloy comprises less than 4.0 wt. % silicon, the metal part is produced via a high pressure die casting process, and the die cast metal part has a thickness of at least 0.2 mm.

[0031] In a further embodiment, the metal alloy is selected from the group consisting of an aluminum alloy, a magnesium alloy, a copper alloy, and a zinc alloy.

[0032] In additional embodiments, the metal alloy is selected from the group consisting of A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075, and AA7068.

[0033] In yet another embodiment, the at least one type of nanoparticle is selected from the group consisting of a metal oxide, a non-metal oxide, a metal carbide, a non-metal carbide, a metal silicide, a metal boride, a metal nitride, and any combination thereof.

[0034] In yet a further embodiment, at least one type of nanoparticle has the structure of a core-shell particle.

[0035] In still further embodiments, the nanoparticles comprise less than 30% by volume of the metal alloy.

[0036] In yet another embodiment, the nanoparticles comprise between 0.1% and 2% by volume of the metal alloy.

[0037] In a further embodiment, the metal alloy comprises AA6061 and the nanoparticles comprise TiC, wherein the TiC nanoparticles comprise 1.0% by volume of the metal alloy.

[0038] In yet another embodiment, the high pressure die casting process uses a pressure between 30 MPa and 100 MPa.

[0039] In yet another embodiment, the high pressure die casting process uses a pressure of greater than 100 MPa.

[0040] In yet a further embodiment, the high pressure die casting process comprises cooling at a cooling rate of between 100° C. / s and 300° C. / s.

[0041] In an additional embodiment, the metal component is anodized for at least one color.

[0042] Another embodiment includes a method for improving the castability of a metal alloy comprising incorporating at least one type of nanoparticles into the metal alloy, wherein the metal alloy comprises less than 4.0 wt. % silicon, the nanoparticles constitute less than 30 vol. % of the metal alloy, and the metal alloy is compatible with a high pressure die casting process.

[0043] In still further embodiments, the metal alloy is selected from the group consisting of an aluminum alloy, a magnesium alloy, a copper alloy, and a zinc alloy.

[0044] In additional embodiments, the metal alloy is selected from the group consisting of A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075, and AA7068.

[0045] In yet another embodiment, the at least one type of nanoparticle is selected from the group consisting of a metal oxide, a non-metal oxide, a metal carbide, a non-metal carbide, a metal silicide, a metal boride, a metal nitride, and any combination thereof.

[0046] In a further embodiment, at least one type of nanoparticle has the structure of a core-shell particle.

[0047] In still further embodiments, the nanoparticles comprise between 0.1% and 2% by volume of the metal alloy.

[0048] In yet another embodiment, the metal alloy comprises AA6061 and the nanoparticles comprise TiC, the TiC nanoparticles comprising 1.0% by volume of the metal alloy.

[0049] In yet another embodiment, the high pressure die casting process uses a pressure between 30 MPa and 100 MPa.

[0050] In yet an additional embodiment, the high pressure die casting process uses a pressure of greater than 100 MPa.

[0051] In yet another embodiment again, the high pressure die casting process includes cooling at a cooling rate of 100° C. / s to 300° C. / s.

[0052] Additional embodiments and features are set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by practice of the present disclosure. A further understanding of the nature and advantages of the present disclosure can be realized by reference to the remaining portions of the specification and the drawings that form a part of this disclosure.

[0053] The description will be more fully understood with reference to the following drawings. The drawings are presented as exemplary embodiments of the invention and should not be construed as a complete recitation of the scope of the invention. It should be noted that the patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. [Brief description of the drawings]

[0054] [Figure 1] FIG. 1 illustrates a high pressure die casting process according to an embodiment of the present invention.

[0055] [Figure 2A] FIG. 2A illustrates a nanoparticle-free high pressure die cast AA6061 part according to an embodiment of the present invention.

[0056] [Figure 2B] FIG. 2B illustrates a high pressure die cast AA6061 part containing 1.0 vol. % TiC nanoparticles according to an embodiment of the present invention.

[0057] [Diagram 3] 3A-3B illustrate colored die-cast AA6061 parts containing 1.0 vol. % nanoparticles after anodization. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] Detailed Description of the Invention Turning now to the drawings, methods and systems for high pressure die casting using low silicon content metal alloys are described. Many embodiments provide low silicon content metal alloys, including but not limited to, aluminum alloys modified with nanoparticles for high pressure die casting processes. Die casting processes according to some embodiments produce metal parts with high strength, high ductility, and high thermal conductivity. Certain embodiments provide die cast metal parts that can be anodized to produce parts with desired colors. Some embodiments show that nanoparticles can enhance the flowability of aluminum alloys under high pressure, avoiding challenges including but not limited to die sticking and hot cracking during die casting. Nanoparticle modified metal alloys according to certain embodiments enable die cast high performance metal alloys with low or no silicon content. High performance aluminum alloys with low silicon content are traditionally impossible to die cast due to issues such as hot cracking. Die cast metal alloys with low silicon content according to some embodiments may enable mass production of aluminum alloys with high strength, excellent ductility and thermal conductivity. Many embodiments show that aluminum alloys with low silicon content are believed to enable good anodizing ability to provide colorful parts. In many embodiments, the combination of strength and ductility can enable die-cast metal parts for structural components. In certain embodiments, in addition to good strength and ductility, the high thermal conductivity of die-cast aluminum parts can enable efficient thermal management in applications including, but not limited to, heat sinks and heat exchangers.

[0059] Typically, nanoparticles may increase the viscosity of the molten metal alloy, which may not be ideal for high pressure die filling and rapid cooling process during die casting. However, nanoparticles according to many embodiments enable die casting of high performance alloys, including but not limited to high performance wrought and cast aluminum alloys having silicon content of about 0% to about 4.0% by weight for structural applications. Some embodiments show that nanoparticles can enhance the fluidity of the alloy while eliminating hot tearing during rapid cooling. The enhanced fluidity of the metal alloy according to certain embodiments may be compatible with die filling process under high pressure. In various embodiments, the pressure for the die casting process may range from about 30 MPa to about 100 MPa, or less than about 30 MPa, or more than about 100 MPa. As can be easily recognized, any of the various pressures may be utilized as appropriate for the requirements of a particular application according to various embodiments of the present invention.

[0060] Many embodiments demonstrate that metal alloys that are resistant to hot tearing can withstand a cooling process at high cooling rates. In some embodiments, the cooling rate can be from about 100° C. / s to about 300° C. / s, or less than about 100° C. / s, or more than about 300° C. / s. As can be readily appreciated, any of a variety of cooling rates can be utilized as appropriate for the requirements of a particular application according to various embodiments of the present invention.

[0061] The improved flowability and castability of metal alloys with nanoparticles according to certain embodiments allows for die casting of metal parts having thicknesses of about 0.2 mm to about 0.5 mm, or greater than about 0.5 mm.

[0062] In some embodiments, the die cast metal alloy has a ductility and / or elongation less than or equal to about 20%, or less than or equal to about 30%. In some embodiments, the die cast metal alloy may have a strength greater than or equal to about 500 MPa. The thermal conductivity of the die cast metal alloy may be less than or equal to about 230 W / mw, or greater than about 230 W / mw, according to many embodiments. The ductility, strength, and thermal conductivity are measured on the as cast metal alloy without post processing.

[0063] In some embodiments, the die-cast metal parts may be anodized to impart any desired color. Examples of anodized colors include, but are not limited to, red, blue, pink, gold, yellow, green, and any combination thereof. As can be readily appreciated, any of a variety of colors may be utilized as appropriate for the requirements of a particular application according to various embodiments of the present invention.

[0064] For purposes of the present invention, the term "die casting" may also be construed as "high pressure die casting" unless otherwise specified.

[0065] High pressure die casting processes according to various embodiments of the present invention are discussed further below. High Pressure Die Casting

[0066] Die casting can be an economical mass production method for metal parts. During the die casting process, molten metal can be injected into a mold under high pressure prior to solidification at high cooling rates (ranging from about tens of degrees Celsius per second to about hundreds of degrees Celsius per second). The applied pressure can be hydraulic or pneumatic. This pressure can be maintained until the cast part solidifies. The mold, known as a die, can be made from high quality tool steel and can produce geometrically complex parts, giving the process a high degree of precision and repeatability. The high pressure filling of the die in high pressure die casting allows the molten alloy to be ejected quickly, which can allow for a highly productive automated process.

[0067] In contrast to gravity die casting (also known as permanent mold casting), in which the molten metal is poured into the mold from above purely under gravity, gravity die casting relies on gravity to fill the mold, making the process relatively slow and therefore may not be well suited for mass production runs.

[0068] High pressure die casting may have advantages including (but not limited to) high dimensional accuracy, smooth cast surface, reduction or elimination of secondary machining operations, fast production speed, etc. However, one disadvantage of high pressure die casting is that the process is limited to metals with high fluidity. Because the injection process is under high pressure (about 30 MPa to about 100 MPa) and the molten alloy is solidified at a high cooling rate (about tens to hundreds of degrees Celsius per second), low fluidity molten alloys and / or high viscosity molten alloys may clog the mold cavity and affect the accuracy of the cast part. In addition to high fluidity, alloys suitable for high pressure die casting should have good resistance to cracking under high pressure and high cooling rate.

[0069] Anodizing is a process in which an alloy part is used as the anode and stainless steel, chromium or a conductive electrolyte is used as the cathode in a suitable electrolyte. Under certain voltage and current conditions, the anode oxidizes to obtain an anodizing film on the surface of the workpiece. Sulfuric acid anodizing can be used in the anodizing and coloring process. Anodizing can provide color and / or a protective film on the die-cast alloy. Metal alloys for high pressure die casting

[0070] A wide variety of metal alloys can be used in high pressure die casting, including, but not limited to, zinc alloys, aluminum alloys, copper alloys, and tin alloys. Aluminum alloys are widely used in home appliances, automobiles, aerospace, shipbuilding, and other fields due to their plasticity, corrosion resistance, and light weight. Die cast aluminum parts find a wide range of applications in industries including computer devices, communication devices, home appliances, automobiles, buildings, windows, aerospace, and sports. High pressure die casting often operates at high cooling rates, tens to hundreds of degrees Celsius per second for metals, so the fluidity and hot cracking resistance of the alloy can be important to the integrity of the part, especially for thin wall structures. Traditional high performance aluminum alloys, including but not limited to A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075 and AA7068, offer good strength, ductility and fatigue life, as well as anodizing ability and thermal conductivity. Unfortunately, these alloys are not suitable for die casting due to challenges of poor fluidity and hot tearing.

[0071] Al-Si alloys are one of the most common die-cast aluminum alloys. Silicon may aid alloy fluidity, mainly due to its high heat of crystallization. As silicon solidifies, a large amount of heat may be released to reheat the liquid aluminum and enhance melt fluidity. For die-cast alloys, silicon content of more than 4.5% by weight (often in the range of about 8% to about 13% by weight) and appropriate alloying elements including, but not limited to, Fe and / or Mn are added to ensure high fluidity and hot-crack resistance. Thus, die-cast aluminum alloys and die-cast parts generally contain silicon content of more than about 4.5% by weight. Examples of Al-Si alloys suitable for die casting include, but are not limited to, AA360, A360, AA380, AA383, AA384, B390, AA413, A413, and C443.

[0072] However, the silicon phase in the Al-Si alloy may appear gray or black after anodizing, and the anodized alloy and / or parts may appear dark, which may be undesirable in many applications with appearance requirements. With increasing silicon content, the color of the anodized film changes from light gray to dark gray to blackish gray. Therefore, cast aluminum alloys with high silicon content may not be suitable for anodizing. In addition, high content of silicon, as well as other elements used to address the fluidity and hot tearing of aluminum die cast alloys, may deteriorate the ductility and thermal and / or electrical conductivity of the aluminum alloy after die casting.

[0073] There are several aluminum alloy systems with low silicon content. An example of an aluminum alloy with low silicon content is the Al-Mg system, such as AA 518, Al-8Mg, etc. Another example of a low silicon aluminum alloy is the Al-Mg-Si system. The Al-Mg-Si system may contain 2% to 5.5% by weight Mg, 1.5% to 3% by weight Si, traces of Mn, traces of Fe, and the balance is Al. Examples of Al-Mg-Si alloys include, but are not limited to, Magsimal-59, C446, Aural-11, Calypso 53, and 54SM. However, aluminum alloys with these low silicon contents may be difficult to die cast due to low fluidity and high cracking tendency. In addition, such alloys may be very sensitive to wall thickness, especially thin walls. Furthermore, low silicon aluminum alloys may require toxic Be as an additive and may be susceptible to hot cracking and stress corrosion cracking. Additionally, their thermal conductivity may be low due to their alloy content.

[0074] Table 1 below, reproduced from the North American Die Casting Association (NADCA), contains the chemical compositions of various Al-Si and Al-8Mg alloys used in high pressure die casting. All single values ​​are maximum composition percentages unless otherwise stated. [Table 1]

[0075] Table 2 below, reproduced from NADCA, contains the mechanical properties of aluminum alloys used in high pressure die casting. Representative values ​​are based on "as cast" characteristics for separate die cast specimens rather than specimens cut from production cast parts. [Table 2]

[0076] Table 3 below, reproduced from NADCA, contains the mechanical properties of magnesium alloys, Zamak die cast alloys, and ZA die cast alloys used in high pressure die casting. [Table 3] High pressure die casting using nanoparticle modified metal alloys

[0077] In many embodiments, the nanoparticle modified metal alloys can enable die casting of high performance metal alloys. In some embodiments, the nanoparticle modified aluminum alloys have low or no silicon content. Some embodiments show that modified nanoparticles in metal alloys enable high performance processing and casting alloys, including but not limited to aluminum alloys with low silicon content, for structural applications. In certain embodiments, the silicon content of the nanoparticle modified metal alloys is about 0% to about 4.0% by weight. As can be easily recognized, any of a variety of silicon contents less than about 4.0% by weight can be utilized as appropriate for the requirements of a particular application according to various embodiments of the present invention. Many embodiments show that the nanoparticles can enhance the fluidity (die filling) of the alloy and simultaneously eliminate hot tearing under high cooling rates without the addition of silicon contents greater than about 4.0% by weight.

[0078] Some embodiments show that metal alloys that may be modified with nanoparticles include at least one metal element, including but not limited to aluminum (Al), magnesium (Mg), iron (Fe), silver (Ag), copper (Cu), manganese (Mn), nickel (Ni), titanium (Ti), chromium (Cr), cobalt (Co), zinc (Zn), and alloys, mixtures or other combinations of two or more of the aforementioned metals, Al alloys, Mg alloys, Zn alloys, Ti-Al alloys, Al-Mg alloys, and Mg-Zn alloys, as well as alloys, mixtures or other combinations of one or more of the aforementioned metals with other elements, such as steel (e.g., iron-carbon alloys or iron-chromium-carbon alloys). As can be readily appreciated, any of a variety of metal alloys can be utilized as appropriate for the requirements of a particular application according to various embodiments of the present invention. In accordance with many embodiments, alloy systems that are traditionally difficult to die cast become suitable for die casting after modification with nanoparticles. In some embodiments, aluminum alloys, magnesium alloys, and zinc alloys can be modified with nanoparticles to be compatible with high pressure die casting. Numerous embodiments show that the alloy systems modified with nanoparticles for die casting also have desirable mechanical performance, thermal conductivity, and electrical conductivity. Examples of alloy systems include, but are not limited to, A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075, and AA7068. As can be readily appreciated, any of a variety of alloy systems can be utilized as appropriate for the requirements of a particular application according to various embodiments of the present invention.

[0079] Many embodiments indicate that the nanoparticles are uniformly dispersed in the metal alloy matrix. Many embodiments indicate that the materials from which the nanoparticles can be made include, but are not limited to, ceramics, oxides, nitrides, borides, carbides and other carbon-based particles, metals and metal alloys, and core-shell particles. Specific examples of types of nanoparticles that can be dispersed in a metal matrix include aluminum oxide nanoparticles, aluminum nitride nanoparticles, carbon nanotubes, silicon carbide nanoparticles, silicon nitride nanoparticles, titanium carbide nanoparticles, titanium boride nanoparticles, titanium carbonitride nanoparticles, tungsten carbide nanoparticles, and core-shell particles. In addition, the nanoparticles can be core-shell type nanoparticles that include a core material and a coating. Examples include SiC nanoparticles coated with SiO, and ceramic nanoparticles coated with metals such as nickel or silver (see, for example, U.S. Patent No. 9,023,128 B2 to Li et al., the disclosure of which is incorporated herein by reference in its entirety).

[0080] In some embodiments, the nanoparticles may include one or more ceramics, although other nanoparticle materials are contemplated, including metals or other conductive materials. Examples of suitable nanoparticle materials include metal oxides (e.g., alkaline earth metal oxides, post-transition metal oxides, and transition metal oxides, such as aluminum oxide (Al2O3), magnesium oxide (MgO), titanium oxide (TiO2), yttrium oxide (Y2O3), magnesium aluminate (MgAl2O4), and zirconium oxide (ZrO2)), non-metal oxides (e.g., silicon oxide (SiO2)), metal carbides (e.g., transition metal carbides, such as titanium carbide (TiC), niobium carbide (NbC), chromium carbide (Cr3C2), nickel carbide (NiC), hafnium carbide (HfC), vanadium carbide (VC), tungsten carbide (WC), and zirconium carbide (ZrC ... Examples of suitable metal carbides include metal carbides (e.g., silicon carbide (SiC)), metal silicides (e.g., transition metal silicides, e.g., titanium silicide (Ti5Si3)), metal borides (e.g., transition metal borides, e.g., titanium boride (TiB2), zirconium boride (ZrB2), hafnium boride (HfB2), vanadium boride (VB2), and tungsten boride (W2B5)), metal nitrides (e.g., transition metal nitrides), core-shell particles, metals (e.g., transition metals in elemental form such as tungsten (W)), alloys, mixtures, or other combinations of two or more of the foregoing, as well as alloys, mixtures, or other combinations of one or more of the foregoing with other elements. Specific examples of suitable nanoparticle materials include transition metal-containing ceramics, such as transition metal carbides, transition metal silicides, transition metal borides, transition metal nitrides, and other non-oxide transition metal-containing ceramics, where the presence of the transition metal can impart a larger Hamaker constant that more closely approximates the Hamaker constant of the metal matrix such that the van der Waals forces are sufficiently reduced (see, for example, U.S. Pat. No. 11,040,395 B2 to Li et al., the disclosure of which is incorporated herein by reference in its entirety).

[0081] In many embodiments, the nanoparticles may have an average diameter of less than about 500 nm. In some embodiments, the nanoparticles may have an average diameter of about 1 nm to about 500 nm, about 1 nm to about 400 nm, about 1 nm to about 300 nm, about 1 nm to about 200 nm, about 1 nm to about 100 nm, about 1 nm to about 70 nm, about 1 nm to about 50 nm, about 1 nm to about 30 nm. Some embodiments indicate that the size distribution of the nanoparticles may be characterized by a standard deviation relative to the average diameter that is up to about 100%, up to about 90%, up to about 80%, up to about 70%, up to about 60%, or up to about 50% of the average diameter. In certain embodiments, the nanoparticles may have a generally spherical or ellipsoidal shape, although other shapes and configurations of nanoparticles are contemplated.

[0082] Many embodiments indicate that the metal alloy may include nanoparticles in a volume percentage ranging from about 0.1%-2%, about 0.25%-2%, about 0.5% or more, about 1% or more, about 2% or more, about 3% or more, about 5% or more, about 6% or more, about 7% or more, about 8% or more, about 9% or more, about 10% or more, about 15% or more, about 20% or more, or about 25% or more, and up to about 30% or more. As can be readily appreciated, any of a variety of nanoparticle concentrations can be utilized as appropriate for the requirements of a particular application according to various embodiments of the present invention.

[0083] Some embodiments show that die cast metal alloys, including but not limited to aluminum alloys with silicon content less than 4%, exhibit desirable mechanical properties, thermal conductivity, and electrical conductivity. The mechanical properties, thermal conductivity, and electrical conductivity are measured on the as-cast metal alloys without post processing. Some embodiments show that low volume percentages (about 0.1% to about 2%) of nanoparticles can be successfully applied to die cast aluminum alloys that are traditionally difficult or impossible to cast. Examples of such alloys include, but are not limited to, AA6061 (Al-1.0Mg-0.6Si-0.25Cu), AA6063 (Al-0.7Mg-0.4Si), A206 (Al-4.5Cu-0.3Mg), AA7075 (Al-5.6Zn-2.6Mg-1.6Cu), and modified AA7075 (Al-5.6Zn-2.6Mg-0.65Cu) for natural aging. These die cast alloys according to some embodiments exhibit good die castability while providing high strength and good ductility. Strength and ductility are measured on the as-cast alloys without post processing. Many die cast alloys are manufactured using the same die cast alloys. In embodiments, die cast AA6061 and other 6000 series aluminum alloys may provide better ductility and / or elongation of less than or equal to about 30%, or from about 20% to about 30%, or from about 20% to about 20%, or from about 10% to about 20%, or from about 10% to about 10%, and thermal conductivity of less than or equal to about 230 W / mw, or from about 200 W / mw to about 230 W / mw, or from about 100 W / mw to about 200 W / mw, or from about 100 W / mw to about 100 W / mw (see Table 2 above).

[0084] Many embodiments provide for high pressure die casting of 7000 series aluminum alloys. Die cast 7000 series aluminum alloys may broaden the application of die casting of high strength aluminum alloys. Modified AA7075 alloys may be able to provide extremely high strength by natural aging after die casting according to embodiments.

[0085] The increased fluidity and hot tear resistance of nanoparticle modified metal alloys according to some embodiments allows for the production of thin walled structures using high pressure die casting processes due to the low silicon content of the die cast metal alloys. Many embodiments produce die cast metal parts having thicknesses of about 0.2 mm to about 0.5 mm, or greater than or equal to about 0.5 mm.

[0086] Some embodiments show that the thermal conductivity of die-cast metal alloys can be affected by porosity. Typically, high pressure die casting of aluminum parts has a porosity of about 3% to about 5%. Certain embodiments show that the porosity of die-cast nanoparticle-infused metal alloys can vary in different parts. The porosity of die-cast parts can be improved in vacuum die casting or process optimization.

[0087] Many embodiments show good anodizing ability and quality of die-cast metal alloys with nanoparticles. Traditionally, die-cast aluminum alloys have a high Si content. Anodizing high Si content alloys may cause the Si to stand out and turn the metal parts gray or black. Therefore, high Si content alloys may not be able to produce a variety of colors through anodizing. In some embodiments, metal alloys with nanoparticles have a Si content of less than 4 wt.% and can be anodized to produce parts with various colors. The color can be determined by the dye used to color the surface porous oxide after chemical treatment. Some embodiments show that any color can be applied to the die-cast metal alloy. Metal alloys containing nanoparticles can also be successfully anodized to various colors due to the low or no effect of silicon.

[0088] Some embodiments show that post-processing may be applied to die-cast metal alloys containing nanoparticles, but is not required. Typically, any solution treatment is not desired for high pressure die-cast alloys due to blistering effects. In some embodiments, post-processing including, but not limited to, T5 or natural aging may be applied. In certain embodiments, post-processing including, but not limited to, T6 may be applied to die-cast metal parts with low or no porosity (e.g., after vacuum high pressure die casting). As can be easily recognized, any of a variety of post-processing treatments may be utilized as appropriate for the requirements of a particular application according to various embodiments of the present invention.

[0089] Many embodiments provide a high pressure die casting process using a metal alloy infused with nanoparticles. In some embodiments, the metal alloy, including but not limited to aluminum alloys, magnesium alloys, and zinc alloys, has a silicon content of less than about 4% by weight. A high pressure die casting process according to an embodiment of the invention is illustrated in FIG. 1. The process 100 begins by providing 101 a metal alloy containing metal and / or nanoparticles. In some embodiments, the nanoparticles may be uniformly incorporated and dispersed in the metal matrix. In some embodiments, the nanoparticles may have a volume ratio of about 0.1% to about 2% in the metal alloy. Certain embodiments include nanoparticles made of metal oxides (e.g., alkaline earth metal oxides, post-transition metal oxides, and transition metal oxides, such as aluminum oxide (Al2O3), magnesium oxide (MgO), titanium oxide (TiO2), yttrium oxide (YO3), magnesium aluminate (MgAl2O4), and zirconium oxide (ZrO2)), non-metal oxides (e.g., silicon oxide (SiO2)), metal carbides (e.g., transition metal carbides, such as titanium carbide (TiC), niobium carbide (NbC), chromium carbide (Cr3C2), nickel carbide (NiC), hafnium carbide (HfC), vanadium carbide (VC), titanium carbide (TiC ... In accordance with the present invention, it is shown that the nanoparticles can be made of materials including, but not limited to, metal carbides (e.g., silicon carbide (SiC)), metal silicides (e.g., transition metal silicides, e.g., titanium silicide (Ti5Si3)), metal borides (e.g., transition metal borides, e.g., titanium boride (TiB2), zirconium boride (ZrB2), hafnium boride (HfB2), vanadium boride (VB2), and tungsten boride (W2B5)), metal nitrides (e.g., transition metal nitrides), core-shell particles, metals (e.g., transition metals in elemental form such as tungsten (W)).Previous work has described in detail the preparation of nanoparticles mixed with metal alloys (see, e.g., Li et al., PCT Application No. PCT / US20 / 27775; Li et al., U.S. Pat. No. 9,322,084 B2; Li et al., U.S. Pat. No. 9,023,128 B2, the disclosures of which are incorporated herein by reference in their entireties).

[0090] The metal mixed with the nanoparticles can be melted and further alloyed to form a molten metal alloy having a certain composition 102. Aluminum alloys including, but not limited to, AA6061, AA6063, AA6069, AA2024, AA5083, AA7075, A206, A201, AA6013, AA2024, AA7034, AA7050, and AA7068 can be prepared for high pressure die casting. Many embodiments show that the metal alloy mixed with the nanoparticles has less than about 4 wt.% silicon to improve the mechanical properties, thermal conductivity, and anodizing ability of such alloys.

[0091] The mold cavity can be prepared 103 prior to injecting the molten metal alloy. The interior of the die can be sprayed with a layer of lubricant to facilitate demolding of the cast metal part. The molten metal alloy can be injected 104 into the die under high pressure. Many embodiments indicate that the pressure for injecting the molten metal alloy ranges from about 30 MPa to about 100 MPa. In certain embodiments, the pressure can be less than about 30 MPa or greater than about 100 MPa. In some embodiments, the pressure can be greater than 100 MPa. The pressure is maintained until the cast part solidifies. The die is then cooled 105 at a high cooling rate. In some embodiments, the cooling rate can range from about 100° C. / s to about 300° C. / s to solidify the molten metal alloy. In many embodiments, the cooling rate can be less than about 100° C. / s or greater than about 300° C. / s. The nanoparticles can improve the flowability and hot cracking resistance and reduce sticking to the die of metal alloys with low silicon content, thus making alloys containing less than 4% silicon by weight compatible with high pressure injection and rapid cooling processes. Once the metal alloy has solidified, the metal part can be salvaged (not shown).

[0092] The die-cast metal part can be anodized 106 to impart a desired color. Anodization can be optional. A high silicon content in a metal alloy can appear gray or black after anodization. In comparison, a nanoparticle-modified metal alloy has less than 4% silicon by weight compared to the usual 8% to 10% silicon by weight. A low silicon metal alloy according to many embodiments does not appear gray or black after anodization. Thus, a die-cast metal part including a nanoparticle-modified metal alloy can be anodized to impart any color of choice, including, but not limited to, red, blue, green, yellow, silver, and gold.

[0093] Die-cast aluminum alloy samples according to embodiments of the present invention are illustrated in Figures 2A and 2B. Figure 2A illustrates a die-cast AA6061 alloy sample. The AA6061 alloy used in Figure 2A is not modified with nanoparticles. The die-cast sample shows multiple crack lines 201. Figure 2B illustrates a die-cast AA6061 alloy modified with about 1.0 vol.% TiC nanoparticles. The die-cast sample has a smooth surface. The sample is anodized to obtain a red color. Exemplary embodiments

[0094] Although specific embodiments of the systems and methods are discussed in the following sections, it will be understood that these embodiments are provided by way of example and not intended to be limiting. EXAMPLES

[0095] Example 1 High pressure die casting of AA6061 alloy Many embodiments provide high pressure die casting of aluminum alloys, including but not limited to high performance AA6061 alloy. In some embodiments, the AA6061 alloy may be modified with about 1.0 vol.% nanoparticles, including but not limited to TiC nanoparticles. Table 4 below lists the properties of die cast AA6061 alloy containing about 1.0 vol.% nanoparticles. The nanoparticle modified AA6061 alloy has an as-cast ultimate tensile strength of about 205 MPa, a yield strength of about 125 MPa, an elongation of about 16%, and a thermal conductivity of about 140 W / mk. Post processing may further improve the mechanical properties. After T5 treatment, the AA6061 alloy has an ultimate tensile strength of about 226 MPa, a yield strength of about 165 MPa, an elongation of about 10%, and a thermal conductivity of about 142 W / mk. After T6 treatment, the AA6061 alloy has an ultimate tensile strength of about 353 MPa, a yield strength of about 305 MPa, an elongation of about 9%, and a thermal conductivity of about 145 W / mk. [Table 4]

[0096] Die cast aluminum alloys, including but not limited to AA6061 alloy, may be anodized to impart any color of choice. Die cast parts of AA6061 exhibiting various colors according to embodiments of the present invention are illustrated in FIGS. 3A-3D. In FIGS. 3A-3D, the die cast AA6061 parts contain about 1.0 vol.% TiC nanoparticles. FIG. 3A shows that the die cast parts may be anodized to have a gold color. FIG. 3B shows that the die cast aluminum parts may be anodized to have a red color. FIG. 3C shows that the die cast parts may be anodized to have a silver color. FIG. 3D shows that the die cast alloys may be anodized to have a blue color. The die cast metal parts exhibit a smooth surface without cracks. Example 2 High pressure die casting of A206 alloy

[0097] Some embodiments demonstrate high pressure die casting of aluminum alloys, including but not limited to high performance A206 alloy. In the case of A206 alloy, nanoparticles allow for much better flowability and eliminate hot cracking, allowing reliable die casting of this traditionally difficult to die cast alloy according to many embodiments. The addition of nanoparticles also improves die filling, pressure resistance, strength and ductility of the parts. Die cast A206 alloy with nanoparticles can provide strengths up to about 450 MPa and elongations up to 15%. Doctrine of Equivalents

[0098] This description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form described, and many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application. This description enables those skilled in the art to best utilize and practice the invention in various embodiments with various modifications suited to a particular use. The scope of the invention is defined by the following claims.

[0099] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Reference to an object in the singular is intended to mean "one or more" and not "one and only," unless clearly stated as such.

[0100] As used herein, the terms "approximately" and "about" are used to describe and explain small variations. When used in conjunction with an event or situation, this term can refer to the exact occurrence of the event or situation, and the approximate occurrence of the event or situation. When used in conjunction with a numerical value, this term can refer to a range of variation of less than or equal to ±10% of the numerical value, for example, less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%.

[0101] Furthermore, amounts, ratios and other numerical values ​​may be presented in range format in some cases herein. It is understood that such range format is used for convenience and conciseness, and should be understood flexibly to include not only the numerical values ​​expressly specifying the limits of the range, but also all individual numerical values ​​or subranges encompassed within the range as if each numerical value and subrange were expressly specified. For example, a ratio range of about 1 to about 200 should be understood to include not only the explicitly recited limits of about 1 and about 200, but also individual ratios such as about 2, about 3, and about 4, and subranges such as about 10 to about 50, about 20 to about 100, etc.

Claims

1. 1. A metal alloy for high pressure die casting comprising: a metal alloy selected from the group consisting of an aluminum alloy, a magnesium alloy, a copper alloy, and a zinc alloy; at least one type of nanoparticles dispersed in said metal alloy; Including, the metal alloy comprises less than 4.0 wt.% silicon; 1. A metal alloy, wherein the metal alloy is compatible with high pressure die casting processes.

2. 2. The metal alloy of claim 1, wherein the metal alloy is selected from the group consisting of A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075, and AA7068.

3. 2. The metal alloy of claim 1, wherein the at least one type of nanoparticles is selected from the group consisting of metal oxides, non-metal oxides, metal carbides, non-metal carbides, metal silicides, metal borides, metal nitrides, and any combination thereof.

4. The metal alloy of claim 1, wherein said at least one type of nanoparticles has a core-shell particle structure.

5. The metal alloy of claim 1 , wherein the nanoparticles comprise less than 30% by volume of the metal alloy.

6. The metal alloy of claim 1 , wherein the nanoparticles comprise between 0.1% and 2% by volume of the metal alloy.

7. 2. The metal alloy of claim 1, wherein the metal alloy comprises AA6061, the nanoparticles comprise TiC, and the TiC nanoparticles comprise 1.0% by volume of the metal alloy.

8. The metal alloy of claim 1, wherein the high pressure die casting process uses a pressure of 30 MPa to 100 MPa.

9. 2. The metal alloy of claim 1, wherein the high pressure die casting process uses a pressure of greater than 100 MPa.

10. The metal alloy of claim 1, wherein the high pressure die casting process includes a step of cooling at a cooling rate of 100°C / s to 300°C / s.

11. 1. A method for high pressure die casting comprising: Providing a metal alloy modified with at least one type of nanoparticle, the metal alloy comprising a silicon weight concentration of less than 4.0%; melting the metal alloy and filling a die with the molten metal alloy under a pressure, the pressure being compatible with the high pressure die casting process; cooling the die to solidify the molten metal alloy; A method comprising:

12. The method of claim 11 further comprising the step of anodizing the die-cast metal alloy for at least one color.

13. The method of claim 11 , wherein the metal alloy is selected from the group consisting of an aluminum alloy, a magnesium alloy, a copper alloy, and a zinc alloy.

14. 12. The method of claim 11, wherein the metal alloy is selected from the group consisting of A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075, and AA7068.

15. 12. The method of claim 11, wherein the at least one type of nanoparticle is selected from the group consisting of metal oxides, non-metal oxides, metal carbides, non-metal carbides, metal silicides, metal borides, metal nitrides, and any combination thereof.

16. The method of claim 11, wherein the at least one type of nanoparticle has a core-shell particle structure.

17. The method of claim 11 , wherein the at least one type of nanoparticles comprises less than 30% by volume of the metal alloy.

18. The method of claim 11, wherein the nanoparticles comprise between 0.1% and 2% by volume of the metal alloy.

19. 12. The method of claim 11, wherein the metal alloy comprises AA6061, the nanoparticles comprise TiC, and the TiC nanoparticles comprise 1.0% by volume of the metal alloy.

20. 12. The method of claim 11, wherein the as-formed die cast metal alloy has an elongation less than or equal to 30% and an ultimate tensile strength greater than 500 MPa.

21. The method of claim 11 , wherein the die-cast metal alloy has a thickness of at least 0.2 mm.

22. The method of claim 11, wherein the pressure is between 30 MPa and 100 MPa.

23. The method of claim 11 , wherein the pressure is greater than 100 MPa.

24. The method of claim 11, wherein the die is cooled at a cooling rate of 100° C. / s to 300° C. / s.

25. The method of claim 11 further comprising post-processing the die cast metal alloy.

26. 26. The method of claim 25, wherein the post-process is selected from the group consisting of a T5 treatment, a natural aging treatment, and a T6 treatment.

27. A metal alloy; at least one type of nanoparticles dispersed in said metal alloy; A high pressure die cast metal part comprising: the metal alloy comprises less than 4.0 wt.% silicon; The metal part is manufactured via a high pressure die casting process; 1. A high pressure die cast metal part, wherein the die cast metal part has a thickness of at least 0.2 mm.

28. 28. The die cast metal part of claim 27, wherein the metal alloy is selected from the group consisting of an aluminum alloy, a magnesium alloy, a copper alloy, and a zinc alloy.

29. 28. The die cast metal part of claim 27, wherein the metal alloy is selected from the group consisting of A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075, and AA7068.

30. 28. The die cast metal part of claim 27, wherein the at least one type of nanoparticle is selected from the group consisting of metal oxides, non-metal oxides, metal carbides, non-metal carbides, metal silicides, metal borides, metal nitrides, and any combination thereof.

31. 28. The die cast metal part of claim 27, wherein the at least one type of nanoparticles has a core-shell particle structure.

32. 28. The die cast metal part of claim 27, wherein the nanoparticles comprise less than 30% by volume of the metal alloy.

33. 28. The die cast metal part of claim 27, wherein the nanoparticles comprise between 0.1% and 2% by volume of the metal alloy.

34. 28. The die cast metal part of claim 27, wherein the metal alloy comprises AA6061, the nanoparticles comprise TiC, and the TiC nanoparticles comprise 1.0 volume percent of the metal alloy.

35. 28. The die cast metal part of claim 27, wherein the high pressure die casting process uses a pressure of between 30 MPa and 100 MPa.

36. 28. The die cast metal part of claim 27, wherein the high pressure die casting process uses a pressure of greater than 100 MPa.

37. 28. The die cast metal part of claim 27, wherein the high pressure die casting process includes cooling at a cooling rate of 100°C / s to 300°C / s.

38. 30. The die cast metal part of claim 27, wherein the metal part is anodized for at least one color.

39. 1. A method for improving the castability of a metal alloy, comprising: Incorporating at least one type of nanoparticle into the metal alloy Including, the metal alloy comprises less than 4.0 wt.% silicon; the nanoparticles constitute less than 30% by volume of the metal alloy; The method, wherein the metal alloy is compatible with a high pressure die casting process.

40. 40. The method of claim 39, wherein the metal alloy is selected from the group consisting of an aluminum alloy, a magnesium alloy, a copper alloy, and a zinc alloy.

41. 40. The method of claim 39, wherein the metal alloy is selected from the group consisting of A201, AA2024, A206, AA2618, AA5083, AA6013, AA6061, AA6063, AA6069, AA7034, AA7050, AA7075, and AA7068.

42. 40. The method of claim 39, wherein the at least one type of nanoparticle is selected from the group consisting of a metal oxide, a non-metal oxide, a metal carbide, a non-metal carbide, a metal silicide, a metal boride, a metal nitride, and any combination thereof.

43. 40. The method of claim 39, wherein said at least one type of nanoparticle has a core-shell particle structure.

44. 40. The method of claim 39, wherein the nanoparticles comprise between 0.1% and 2% by volume of the metal alloy.

45. 40. The method of claim 39, wherein the metal alloy comprises AA6061, the nanoparticles comprise TiC, and the TiC nanoparticles comprise 1.0% by volume of the metal alloy.

46. 40. The method of claim 39, wherein the high pressure die casting process uses a pressure of 30 MPa to 100 MPa.

47. 40. The method of claim 39, wherein the high pressure die casting process uses a pressure of greater than 100 MPa.

48. 40. The method of claim 39, wherein the high pressure die casting process includes cooling at a cooling rate of 100°C / s to 300°C / s.

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