Anodizable high thermal conductivity die cast aluminum alloy material

Abstract

The application provides anodizable high-thermal-conductivity die-casting aluminum alloy material, which comprises the following components in percentage by mass: 0.01-2.5% of iron, 0.01-4% of lanthanum, 0.01-4% of cerium, 0.001-0.5% of silicon, <0.2% of magnesium, <0.2% of copper, <0.3% of zinc, <0.1% of manganese, <0.2% of zirconium, <0.1% of boron, <0.1% of titanium and <0.15% of other inevitable common impurities, and the rest is aluminum. The anodizable high-thermal-conductivity die-casting aluminum alloy material provided by the application simultaneously realizes the integration of three performance indexes of high thermal conductivity (≥190 W / (m*K)), good die-casting formability and excellent anodizing surface treatment capability.

Description

Technical Field

[0001] This invention belongs to the field of die-cast aluminum alloy technology, specifically relating to an anodizable high thermal conductivity die-cast aluminum alloy material. Background Technology

[0002] Passive heat dissipation components (such as SSD heat sinks, CPU heat sinks, power module heat dissipation substrates, etc.) refer to thin-walled, multi-finned structural components that rely on natural convection and thermal radiation for heat dissipation, and are widely used in computers, communication base stations, consumer electronics and power electronic equipment.

[0003] Currently, passive heat dissipation components are mainly made of the following materials:

[0004] First, wrought aluminum alloys (such as 6063 and 1070) have high thermal conductivity (≥200W / (m·K)) and good anodizing effect, but they are not suitable for die casting and can only be manufactured by extrusion + CNC machining. This process involves many steps, high cost, and low material utilization, making it difficult to meet the low-cost production needs of large-scale, complex thin-walled structures.

[0005] Secondly, traditional die-cast aluminum alloys (such as ADC12 and A380) have good die-casting formability and low cost, but their thermal conductivity is only 80~110W / (m·K), and the high silicon content (5~12%) results in a dark and loose anodized film, making it impossible to obtain a uniform black appearance.

[0006] Thirdly, there are high thermal conductivity die-cast aluminum alloys, mainly including Al-Fe and Al-Fe-Ni alloys. These materials, through the addition of iron to form low-solid-solubility intermetallic compounds, reduce damage to the thermal conductivity of the matrix, achieving a thermal conductivity of 180–200 W / (m·K), and exhibiting acceptable die-casting formability. Among them, the Al-Fe-Ni alloy utilizes nickel to modify the iron phase, refining the size and morphology of the iron-containing phase, thereby improving the alloy's mechanical properties and die-casting formability. However, these materials still have the following shortcomings: First, nickel is a relatively expensive alloying element, significantly increasing material costs; second, even after nickel modification treatment, the iron-containing phase is still difficult to completely eliminate its adverse effects on the anodic oxide film. Iron easily forms residual intermetallic compounds during the anodic oxidation process, leading to color differences, black spots, or streaks in the oxide film, making it impossible to obtain a uniform and aesthetically pleasing black oxide film; third, nickel poses environmental risks and does not comply with increasingly stringent environmental regulations such as RoHS and REACH.

[0007] As the power density and size of electronic devices continue to increase, higher comprehensive requirements are being placed on passive heat dissipation components—high thermal conductivity, good anodizing effect, and die-casting capability are all indispensable. However, among existing material solutions, wrought aluminum alloys cannot be die-cast, traditional die-cast aluminum alloys have low thermal conductivity and poor anodizing effect, and Al-Fe-Ni based high thermal conductivity die-cast aluminum alloys are difficult to meet the application requirements of high heat dissipation components due to the high cost of nickel and poor anodizing effect.

[0008] In summary, there is a lack of existing technologies that can simultaneously satisfy the requirements of die casting, high thermal conductivity (≥180W / (m·K)), good anodizing effect, and controllable cost for aluminum alloy materials. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides an anodizable high thermal conductivity die-cast aluminum alloy based on lanthanum-cerium rare-earth modified iron phase.

[0010] This invention provides an anodizable high thermal conductivity die-cast aluminum alloy material, characterized in that, by mass percentage: iron 0.01–2.5%; lanthanum 0.01–4%; cerium 0.01–4%; silicon 0.001–0.5%; magnesium <0.2%; copper <0.2%; zinc <0.3%; manganese <0.1%; zirconium <0.2%; boron <0.1%; titanium <0.1%; other unavoidable common impurities <0.15%; the remainder being aluminum.

[0011] Preferably, the total amount of lanthanum and cerium is 0.3% to 4.0% by mass percentage.

[0012] Preferably, the total content of lanthanum and cerium is 1.2% to 4.0% by mass percentage.

[0013] Preferably, the ratio of lanthanum to cerium is 0.08 to 12.

[0014] Preferably, the ratio of lanthanum to cerium is 0.08 to 12, and cerium > 0.15%.

[0015] Preferably, the iron content is 0.2% to 1.6%.

[0016] Preferably, the silicon content is 0.03-0.3%.

[0017] Preferably, the lanthanum content is 0.1% to 4%.

[0018] Preferably, the cerium content is 0.1% to 1%.

[0019] Preferably, the anodizable high thermal conductivity die-cast aluminum alloy material is prepared by the following method:

[0020] S1: Add industrial pure aluminum to a smelting furnace and heat it to 730-750℃ to melt it;

[0021] S2: After the aluminum liquid has completely melted, add the aluminum-iron intermediate alloy, stir evenly, and keep warm for 10-15 minutes to allow the iron to dissolve fully;

[0022] S3: Lower the melt temperature to 710-720℃, add aluminum-lanthanum master alloy and aluminum-cerium master alloy, and stir until completely melted;

[0023] S4: Adjust the melt temperature to 715-725℃, introduce high-purity argon or nitrogen for rotary blowing degassing, degassing time 12-15 minutes, so that the hydrogen content of the melt is reduced to ≤0.15mL / 100g Al, and add sodium-free refining agent at the same time.

[0024] S5: After refining, let stand for 10-15 minutes to allow the impurities to float or sink, and then thoroughly remove the surface scum.

[0025] S6: Cool the purified alloy liquid to 700-720℃ and cast it to obtain an ingot.

[0026] The present invention provides an anodizable high thermal conductivity die-cast aluminum alloy material that integrates three major performance indicators: high thermal conductivity (≥190W / (m·K)), good die-casting formability, and excellent anodizing surface treatment capability. Attached Figure Description

[0027] The above and other objects, features, and advantages of the invention will become clearer through a more detailed description of the preferred embodiments illustrated in the accompanying drawings. The same reference numerals denote the same parts throughout the drawings, and the drawings are not intentionally drawn to scale with actual dimensions; the focus is on illustrating the gist of the invention.

[0028] Figure 1 The product photos show the die-cast aluminum alloy materials provided in Examples 1-2 after being die-cast into heat dissipation modules and then anodized.

[0029] Figure 2 The product photos show the die-cast aluminum alloy materials provided in Examples 1-2 after being die-cast into the shell of a beauty device and then anodized.

[0030] Figure 3 Photograph of the product obtained after die-casting the aluminum alloy material provided for Comparative Example 3 into the housing of a beauty device and then anodizing it. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0032] This invention provides an anodizable high thermal conductivity die-cast aluminum alloy material, comprising, by mass percentage: 0.01–2.5% iron; 0.01–4% lanthanum; 0.01–4% cerium; 0.001–0.5% silicon; <0.2% magnesium; <0.2% copper; <0.3% zinc; <0.1% manganese; <0.2% zirconium; <0.1% boron; <0.1% titanium; <0.1% other unavoidable common impurities; and the remainder being aluminum.

[0033] This invention provides an Al-La-Ce series high thermal conductivity die-cast aluminum alloy. Its core innovation lies in the integration of three major performance indicators: high thermal conductivity (≥190W / (m·K)), good die-casting formability, and excellent anodizing surface treatment capability. This forms a unique technical path that is different from traditional Al-Fe-Ni series (or rare earth-Ni series) alloys.

[0034] This patent eliminates nickel and adopts a lanthanum (La) and cerium (Ce) composite rare earth system (total addition not exceeding 5%) to synergistically improve thermal conductivity through the following three mechanisms:

[0035] 1. Modified silicon phase: Transforming coarse needle-like eutectic silicon into fine fibers or particles significantly reduces the scattering of free electrons, which is the main way to improve thermal conductivity;

[0036] 2. Purify the iron phase: Improve the morphology of the acicular iron-rich phase, reduce its cutting effect on the matrix, and reduce the negative impact on thermal conductivity and mechanical properties;

[0037] 3. Refine grains: Make α-Al grains smaller and more uniform, reducing the negative impact of grain boundaries on electron scattering;

[0038] 4. Strengthening effect: Appropriately increasing the content of lanthanum, cerium, and rare earth elements can form an aluminum-rare earth second phase (such as Al). 11 La3, Al 11 Ce3) improves mechanical strength while maintaining high thermal conductivity.

[0039] In Al-Fe-Ni high thermal conductivity alloys, the high iron content results in a dark, insufficiently bright anodic oxide film. For die-cast aluminum alloys with low silicon and relatively low iron content, nickel is often used to improve both thermal conductivity and die-casting performance, forming rare-earth-nickel alloys, which possess very high thermal conductivity. However, considering die-casting performance, the presence of iron is unavoidable in low-silicon aluminum alloys. The addition of nickel does not improve anodizing; instead, the increased non-aluminum content exacerbates the unevenness of anodizing. Therefore, neither Al-Fe-Ni alloys nor rare-earth-Ni alloys can simultaneously achieve both high thermal conductivity and good anodizing effect while maintaining good die-casting and thermal conductivity.

[0040] Furthermore, nickel is a precious metal with a high cost. In the later surface treatment (mainly anodizing) of nickel-containing aluminum products, nickel is easily dissolved in the anodizing bath solution, which aggravates wastewater pollution and is detrimental to environmental protection.

[0041] This patent innovatively adopts a nickel-free solution, proposing an Al-La-Ce series high thermal conductivity die-cast aluminum alloy. Lanthanum and cerium rare earth elements replace nickel in the modification treatment of the iron phase, which promotes rapid anodic oxidation growth and increases the brightness of the film under the same anodic oxidation conditions. This shortens the chemical polishing time in the anodic oxidation process, thereby improving the effect and efficiency of anodic oxidation, resulting in a higher gloss anodic oxidation appearance and a higher yield. Furthermore, by fully utilizing the triple effects of lanthanum and cerium rare earth elements—"modifying the silicon phase, purifying the iron phase, and refining the grains"—thermal conductivity is significantly improved. It successfully achieves a balance between three major performance indicators: high thermal conductivity (≥190W / (m·K)), good die-casting formability, and excellent anodic oxidation surface treatment capability.

[0042] Lanthanum and cerium rare earth elements are abundant and inexpensive in China. This invention eliminates nickel and uses rare earth elements, significantly reducing material costs. Under controllable costs, this provides a more comprehensive and industrially promising basic material option for passive heat dissipation components such as SSD heatsinks, CPU heatsinks, and power module heat sinks.

[0043] In a preferred embodiment, lanthanum comprises 0.1–4% by mass percentage; cerium comprises 0.1–1% by mass percentage, and the total of lanthanum and cerium comprises 0.3–4.0%. In a further preferred embodiment, the total of lanthanum and cerium comprises 1.2–4.0%.

[0044] A sufficient total amount of rare earth elements can fully transform eutectic silicon into fine fibers or particles, purify needle-like iron-rich phases into dispersed particles, and simultaneously form a sufficient amount of Al. 11 La3, Al 11 Ce3 and other aluminum-rare earth second phases refine α-Al grains, thereby achieving a stable thermal conductivity of over 190 W / (m·K) while maintaining good mechanical properties. On the other hand, this rare earth content range can significantly promote the uniform and rapid growth of the anodic oxide film, improve the film density and surface gloss, shorten the chemical polishing time, and obtain a bright silver appearance with higher yield. If the total rare earth content is less than 1.2%, the effects of deterioration, purification, and anodic oxidation promotion are insufficient. If it exceeds 4.5%, coarse aluminum-rare earth particles are easily formed, which in turn increases electron scattering, reduces thermal conductivity, and increases costs.

[0045] In a preferred embodiment, the ratio of lanthanum to cerium is 0.08 to 12, and cerium > 0.15%. In a further preferred embodiment, the ratio of lanthanum to cerium is 0.4 to 1.7 or 8 to 12.

[0046] Within this ratio range, lanthanum and cerium can fully leverage their respective metamorphic advantages: lanthanum excels at refining α-Al grains and improving fluidity, while cerium more efficiently metamorphoses eutectic silicon, purifies the iron phase, and participates in the anodic oxidation film formation reaction. When the cerium content exceeds 0.15%, the metamorphic effect of cerium on the silicon phase and its purification effect on the iron phase are significantly enhanced, effectively converting acicular eutectic silicon and iron-rich phases into fine particles. Simultaneously, cerium promotes the growth of a dense oxide film during anodic oxidation, significantly improving film brightness and uniformity, and shortening chemical polishing time. If the lanthanum-cerium ratio deviates from 0.08~1.7 (e.g., if the proportion of a certain rare earth element is too low), the synergistic effect of the two weakens, and both thermal conductivity and anodic oxidation effect decrease. If the cerium content is ≤0.15%, the metamorphic and anodic oxidation promoting effects of cerium are insufficient, making it difficult to obtain a high-gloss, high-yield anodic oxidation appearance. By synergistically limiting the optimal ratio and the lower limit of cerium content, this invention achieves simultaneous improvement in the brightness, density, and production efficiency of anodic oxide films while maintaining a thermal conductivity ≥190W / (m·K).

[0047] In a preferred embodiment, the iron content is 0.2% to 1.6%. An appropriate amount of iron ensures the die-casting release performance and prevents sticking. The "purification" and "morphology regulation" of the iron phase by rare earth elements significantly reduces the formation of black spots after anodizing. Controlling the iron content below 1.6% further controls the spot density and size. Combined with the effect of cerium on improving the density and brightness of the oxide film, the anodized surface exhibits a uniform, high-gloss silver-white appearance, significantly improving the yield and exhibiting a high thermal conductivity.

[0048] In a preferred embodiment, the silicon content is 0.03-0.3%, and in a more preferred embodiment, it is 0.05-0.18%. Within this low content range, an appropriate amount of silicon will not form coarse eutectic silicon, but will still undergo sufficient modification reactions with rare earth elements (especially cerium). When the silicon content is low, lanthanum-cerium rare earth elements can completely transform it into fine fibrous or granular particles, thereby significantly reducing the negative impact on thermal conductivity. Simultaneously, these dispersed fine silicon phase particles can serve as heterogeneous nucleation cores, further refining the α-Al grains and stabilizing the thermal conductivity to above 190 W / (m·K). If the silicon content is high, the eutectic silicon phase increases, and even after rare earth modification, it is difficult to completely eliminate the adverse effects on electron scattering and the appearance of anodized silicon.

[0049] In a preferred embodiment, the anodizable high thermal conductivity die-cast aluminum alloy material is prepared by the following method:

[0050] S1: Add industrial pure aluminum to a smelting furnace and heat it to 730-750℃ to melt it;

[0051] S2: After the aluminum liquid has completely melted, add the aluminum-iron intermediate alloy, stir evenly, and keep warm for 10-15 minutes to allow the iron to dissolve fully;

[0052] S3: Lower the melt temperature to 710-720℃, add aluminum-lanthanum master alloy and aluminum-cerium master alloy, and stir until completely melted;

[0053] S4: Adjust the melt temperature to 715-725℃, introduce high-purity argon or nitrogen for rotary blowing degassing, degassing time 12-15 minutes, so that the hydrogen content of the melt is reduced to ≤0.15mL / 100g Al, and add sodium-free refining agent at the same time.

[0054] S5: After refining, let stand for 10-15 minutes to allow the impurities to float or sink, and then thoroughly remove the surface scum.

[0055] S6: Cool the purified alloy liquid to 700-720℃ and cast it to obtain an ingot.

[0056] In order to gain a better understanding of the technical solution of the present invention, several preferred embodiments are listed below for further detailed description.

[0057] Example 1:

[0058] By mass percentage: Iron: 1.1%; Silicon: 0.09%; Lanthanum: 0.5%; Cerium: 0.8%; Unavoidable inherent impurities <0.05%; Balance Al. The aluminum alloy is prepared according to the above proportions, following these steps:

[0059] S1: Add industrial pure aluminum to a smelting furnace and heat it to 740℃ to melt it;

[0060] S2: After the aluminum liquid has completely melted, add the aluminum-iron intermediate alloy, stir evenly, and keep warm for 15 minutes to allow the iron to dissolve fully;

[0061] S3: Lower the melt temperature to 720℃, add aluminum-lanthanum master alloy and aluminum-cerium master alloy, and stir until completely melted;

[0062] S4: Adjust the melt temperature to 720℃, introduce high-purity argon or nitrogen for rotary blowing degassing, degassing time is 15 minutes, reduce the hydrogen content of the melt to ≤0.15mL / 100g Al, and add sodium-free refining agent at the same time.

[0063] S5: After refining, let stand for 12 minutes to allow impurities to float or sink, then thoroughly remove the surface scum.

[0064] S6: Cool the purified alloy liquid to 710℃ and cast it to obtain an ingot.

[0065] Example 2 Compared with Example 1, the alloy material composition of Example 2 is as follows: iron: 1.5%; silicon: 0.06%; lanthanum: 2.2%; cerium: 0.2%; unavoidable common impurities <0.05%; balance Al. The preparation method is the same as that of Example 1.

[0066] Example 3

[0067] Compared with Example 1, the alloy material composition of Example 3 is as follows: iron: 0.2%; silicon: 0.12%; lanthanum: 3.5%; cerium: 0.5%; unavoidable common impurities <0.05%; balance Al. The preparation method is the same as that of Example 1.

[0068] Comparative Example 1: The difference between this comparative example and Example 1 is that the alloy material in this comparative example does not contain lanthanum and cerium, the preparation method does not include aluminum-lanthanum master alloy and aluminum-cerium master alloy, and step S3 is omitted. Everything else is the same as in Example 1.

[0069] Comparative Example 2: The difference between this comparative example and Example 1 is that the alloy material in this comparative example does not contain cerium, and no aluminum-cerium master alloy is added in step S3.

[0070] Comparative Example 3: The difference between this comparative example and Example 1 is that the alloy material in this comparative example does not contain cerium, but contains 0.8% nickel, and in step S3, aluminum-cerium master alloy is not added, but aluminum-nickel master alloy is added.

[0071] Example of effect (1) The performance of the ingots obtained from Examples 1-3 and Comparative Examples 1-3 was tested, and the test results are shown in Table 1.

[0072] Table 1

[0073]

[0074] In summary, it can be seen that the anodizable high thermal conductivity aluminum alloy material provided by this invention has high thermal conductivity. Furthermore, the ingots prepared in Examples 1-3 exhibit good die-casting performance, enabling the production of thin-walled products. Anodizing of the die-cast products revealed a good anodizing effect, as shown in the attached figure. Figure 1-2 As shown. (Attached) Figure 1 and attached Figure 2 The sample on the left was obtained from the die-cast aluminum alloy material provided in Example 1; the sample on the right was obtained from the die-cast aluminum alloy material provided in Example 2.

[0075] In Comparative Example 1, there were no rare earth elements, and iron had a greater impact, resulting in an alloy material with a lower thermal conductivity.

[0076] In Comparative Example 2, only lanthanum was present among the rare earth elements, while cerium did not play a major role in metamorphism. As a result, its thermal conductivity still could not reach more than 180 W / (m·K), indicating a relatively low thermal conductivity.

[0077] In Comparative Example 3, instead of adding cerium, 0.8% nickel was added. While nickel has a higher thermal conductivity, the anodizing effect was poor after anodizing the die-cast aluminum alloy material from Comparative Example 3. (See attached image.) Figure 3 As shown.

[0078] In summary, the formulation of this invention is reasonable. The anodizable high thermal conductivity die-cast aluminum alloy material provided by this invention integrates three major performance indicators: high thermal conductivity (≥190W / (m·K)), good die-casting formability, and excellent anodizing surface treatment capability. Under the premise of controllable cost, it provides a more comprehensive and industrially promising basic material option for passive heat dissipation components such as SSD heat sinks, CPU heat sinks, and power module heat dissipation substrates.

[0079] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An anodizable high thermal conductivity die-cast aluminum alloy material, characterized in that, By mass percentage: iron 0.01–2.5%; lanthanum 0.01–4%; cerium 0.01–4%; silicon 0.001–0.5%; magnesium <0.2%; copper <0.2%; zinc <0.3%; manganese <0.1%; zirconium <0.2%; boron <0.1%; titanium <0.1%; other unavoidable common impurities <0.15%; the remainder is aluminum.

2. The anodizable high thermal conductivity die-cast aluminum alloy material as described in claim 1, characterized in that, The total content of lanthanum and cerium, by mass percentage, is 0.3% to 4.0%.

3. The anodizable high thermal conductivity die-cast aluminum alloy material as described in claim 1, characterized in that, The total content of lanthanum and cerium, by mass percentage, is 1.2% to 4.0%.

4. The anodizable high thermal conductivity die-cast aluminum alloy material as described in claim 1, characterized in that, The ratio of lanthanum to cerium is 0.08 to 12.

5. The anodizable high thermal conductivity die-cast aluminum alloy material as described in claim 1, characterized in that, The ratio of lanthanum to cerium is 0.08 to 12, and cerium > 0.15%.

6. The anodizable high thermal conductivity die-cast aluminum alloy material as described in claim 1, characterized in that, The iron content is 0.2% to 1.6%.

7. The anodizable high thermal conductivity die-cast aluminum alloy material as described in claim 1, characterized in that, Silicon content is 0.03-0.3%.

8. The anodizable high thermal conductivity die-cast aluminum alloy material as described in claim 1, characterized in that, Lanthanum content is 0.1%–4%.

9. The anodizable high thermal conductivity die-cast aluminum alloy material as described in claim 1, characterized in that, The cerium content is 0.1% to 1%.

10. The anodizable high thermal conductivity die-cast aluminum alloy material as described in claim 1, characterized in that, The anodizable high thermal conductivity die-cast aluminum alloy material is prepared by the following method: S1: Add industrial pure aluminum to a smelting furnace and heat it to 730-750℃ to melt it; S2: After the aluminum liquid has completely melted, add the aluminum-iron intermediate alloy, stir evenly, and keep warm for 10-15 minutes to allow the iron to dissolve fully; S3: Lower the melt temperature to 710-720℃, add aluminum-lanthanum master alloy and aluminum-cerium master alloy, and stir until completely melted; S4: Adjust the melt temperature to 715-725℃, introduce high-purity argon or nitrogen for rotary blowing degassing, degassing time 12-15 minutes, so that the hydrogen content of the melt is reduced to ≤0.15mL / 100g Al, and add sodium-free refining agent at the same time. S5: After refining, let stand for 10-15 minutes to allow the impurities to float or sink, and then thoroughly remove the surface scum. S6: Cool the purified alloy liquid to 700-720℃ and cast it to obtain an ingot.

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