Al-ce-ni alloy with dual-state eutectic structure, preparation method and application

Abstract

This invention discloses an Al-Ce-Ni alloy with a dual-state eutectic structure, its preparation method, and its applications. The composition of the Al-Ce-Ni alloy is: Ce 11-13%, Ni 2.5-4%, Yb 0.1-0.3%, with the balance being Al and unavoidable impurity elements. The alloy prepared by this invention, through the addition of Ni, forms finely spaced fibrous α-Al / Al alloys. 11 Ce3 / Al3Ni ternary eutectic and Chinese character-shaped α-Al / Al 11 The mixed microstructure of the Ce3 eutectic results in a eutectic phase volume fraction exceeding 20%, leading to more pronounced second-phase strengthening and load transfer effects, thereby improving the alloy's mechanical properties and plasticity. Furthermore, the addition of Yb refines the primary Al... 11 The Ce3 phase was introduced, which caused its morphology to transform into a fine blocky structure and also refined the α-Al / Al phase. 11 The Ce3 eutectic spacing further improves the overall mechanical properties of the alloy.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, specifically to an Al-Ce-Ni alloy with a dual-state eutectic structure, its preparation method, and its application. Background Technology

[0002] Aluminum alloys possess high specific strength, low density, good thermal conductivity, and formability, making them ideal lightweight structural materials for the automotive industry. Aluminum castings, in particular, have a short manufacturing cycle, are inexpensive, and have a density only one-third that of steel structural components, leading to their widespread use in automotive structural parts such as motor housings, cylinder heads, and engine pistons. Currently, aluminum castings used in the automotive industry are primarily made from aluminum-silicon eutectic alloys. However, because the eutectic Si phase in aluminum-silicon eutectic alloys is characterized by sharp, needle-like segments that severely disrupt the aluminum matrix and are prone to stress concentration under load, the castings exhibit poor strength and plasticity, failing to meet the future automotive requirements for high-performance aluminum castings.

[0003] Aluminum-cerium eutectic alloys exhibit flow properties comparable to aluminum-silicon eutectic alloys, along with low hot cracking tendency, good thermal conductivity, and thermal stability, making them a suitable material to replace traditional aluminum castings for automobiles. Cerium is an inexpensive rare earth element, with an abundance of 68 ppm in the Earth's crust, accounting for 28% of all rare earth elements. It is primarily a byproduct of the extraction of expensive rare earth elements. Therefore, cerium can be widely used as a major alloying element for aluminum without significantly increasing production costs.

[0004] The eutectic phase of aluminum-cerium eutectic alloys is Al in the shape of the Chinese character. 11 The Ce3 phase, being small in size and exhibiting interconnected characteristics, can strengthen the alloy through load transfer and second-phase strengthening. However, Al... 11 The Ce3 phase has a weak strengthening ability, resulting in low mechanical properties of aluminum-cerium eutectic alloys. Therefore, it is necessary to control the appropriate eutectic structure to improve the mechanical properties of the alloy and meet the requirements of next-generation automotive aluminum castings. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one deficiency of the prior art and to provide an Al-Ce-Ni alloy with a dual-state eutectic structure, its preparation method, and its application.

[0006] The technical solution adopted in this invention is:

[0007] In a first aspect, the present invention provides an Al-Ce-Ni alloy having a dual-state eutectic structure, wherein the alloy composition, by mass percentage, is: Ce 11-13%, Ni 2.5-4%, Yb 0.1-0.3%, with the balance being Al and unavoidable impurity elements.

[0008] In some instances, the mass ratio of Ce to Ni in the Al-Ce-Ni alloy is (3–5):1.

[0009] In some instances, the Al-Ce-Ni alloy is composed of, by mass percentage: Ce 12%, Ni 3%, Yb 0.3%, with the balance being Al and unavoidable impurity elements.

[0010] In some instances, the unavoidable impurity element content in the Al-Ce-Ni alloy is ≤0.1% by mass.

[0011] In some examples, the Al-Ce-Ni alloy has a eutectic phase volume fraction of not less than 20%, a yield strength of 132–151 MPa at room temperature, a tensile strength of 244–257 MPa, and an elongation of 5.3–7.5%.

[0012] Secondly, the method for preparing the Al-Ce-Ni alloy provided in the first aspect of this invention includes the following steps:

[0013] 1) Batching: Weigh out aluminum raw materials, Ce raw materials, Ni raw materials, and Yb raw materials according to the proportions, clean them thoroughly, and preheat them;

[0014] 2) Smelting: Heat the preheated aluminum raw material to 790-810℃. After the aluminum raw material is completely melted, add the preheated Ce, Ni and Yb raw materials. After melting, cool down to 750-760℃ and stir for 6-10 minutes.

[0015] 3) Refining: After stirring, degassing and refining are carried out in the absence of air, slag is removed and filtered, and the temperature is held at 740-750℃ for 8-10 minutes. The alloy ingot is then cast and demolded.

[0016] In some instances, the preheating temperature in step 1) is 200–230°C, and the preheating time is 30–35 min.

[0017] In some instances, the refining time in step 3) is 5 to 7 minutes.

[0018] In some instances, the Ce raw material is an Al-20Ce alloy, the Ni raw material is an Al-10Ni alloy, and the Yb raw material is an Al-5Yb master alloy.

[0019] Thirdly, the application of the Al-Ce-Ni alloy described in the first aspect of this invention in the preparation of structural components.

[0020] The beneficial effects of this invention are:

[0021] The Al-Ce-Ni alloy of this invention is a eutectic alloy, and its microstructure consists of Chinese character-shaped α-Al / Al... 11 Ce3 binary eutectic and fine fibrous α-Al / Al 11 The Ce3 / Al3Ni ternary eutectic consists of two morphologies. Based on the design concept of refining the eutectic spacing, modifying the eutectic morphology, and increasing the volume fraction of the eutectic phase to strengthen the matrix, this invention employs Ni alloying, which facilitates the L→α-Al + Al transition. 11 The eutectic reaction of Ce3+ Al3Ni introduces a fine α-Al / Al 11 The Ce3 / Al3Ni ternary eutectic alloy increases the volume fraction of the eutectic phase to over 20%. Simultaneously, by controlling the elemental content ratio M(Ce):M(Ni) = 3–5, α-Al / Al... 11 The binary eutectic spacing of Ce3 is 1.5–2 μm, while that of α-Al / Al 11 The ternary eutectic spacing of Ce3 / Al3Ni is 200–250 μm. Fine ternary eutectics are distributed along the boundaries of binary eutectic clusters in the alloy, forming an interconnected network structure in space. This bimodal eutectic structure's distribution and size characteristics are beneficial for regulating strain distribution during alloy deformation, thereby improving the alloy's plasticity. Furthermore, the eutectic phase volume fraction of the Al-Ce-Ni alloy is not less than 20%, more than twice that of the binary Al-Ce eutectic. The large volume fraction of the eutectic phase can bring more significant load transfer and second-phase strengthening effects, greatly improving the alloy's overall mechanical properties.

[0022] The Al-Ce-Ni alloy of this invention incorporates trace amounts of Yb, which modifies the primary Al. 11 Morphology and size of the Ce3 phase. During the initial solidification phase, Yb is bound by primary Al... 11 Ce3 phase is expelled and enriched in front of the solid-liquid interface, leading to solute redistribution, increasing compositional supercooling, and hindering Al... 11 The small-faceted growth of the Ce3 phase ultimately led to the formation of primary Al 11 The Ce3 phase transforms from elongated blocky to fine blocky, with a size of 50–60 μm. Furthermore, referring to the binary alloy phase diagram, the eutectic temperature of Al-Yb is approximately 625℃, while that of Al-Ce is approximately 640℃, leading to the binary eutectic reaction L→α-Al + Al. 11 In Ce3, Yb is expelled and enriched at the solid-liquid interface, affecting the solute distribution at the solid-liquid interface, disrupting and limiting the coupled growth of the eutectic, and ultimately refining the α-Al / Al... 11 The Ce3 binary eutectic structure is beneficial to improving the mechanical properties of the alloy.

[0023] The main alloying elements of the Al-Ce-Ni alloy of this invention are Ce and Ni. These elements have low solid solubility and low diffusion rate in aluminum, which is beneficial for maintaining the size and morphology of the eutectic structure at high temperatures. This ensures that the alloy's strength does not decrease significantly at high temperatures and still possesses sufficient high-temperature strength. On the one hand, the Chinese character-shaped Al in the binary eutectic region... 11 The Ce3 phase exhibits a low coarsening rate, allowing it to further strengthen the matrix at high temperatures; on the other hand, the Al in the ternary eutectic region... 11 The intertwining and bonding of Ce3 and Al3Ni fibers restricts coarsening at high temperatures, allowing the fine structure of the ternary eutectic to be preserved at high temperatures. The fine and thermally stable biphase eutectic structure is beneficial to improving the high-temperature performance of Al-Ce-Ni alloys.

[0024] The Al-Ce-Ni alloy of this invention has a eutectic phase volume fraction of not less than 20%, a yield strength of 132–151 MPa, a tensile strength of 244–257 MPa, and an elongation of 5.3–7.5% at room temperature, and a yield strength of 105–113 MPa, a tensile strength of 218–233 MPa, and an elongation of 18.5–22.7% at 250°C. This alloy is prepared by gravity casting, a simple and convenient process with a short preparation cycle. Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope image of the ternary eutectic structure of the Al-Ce-Ni alloy prepared in Example 5.

[0026] Figure 2 This is a scanning electron microscope image of the Al-Ce alloy prepared in Comparative Example 2 without the addition of Ni and Yb. Detailed Implementation

[0027] The present invention will now be described in detail with reference to embodiments, comparative examples, and experimental data.

[0028] Based on elemental mass percentage, the chemical composition of the alloys in each embodiment is: Ce 11-13%, Ni 2.5-4%, Yb 0.1-0.3%, with unavoidable impurity element content ≤0.1%, and the balance being Al. The raw materials selected are 99.7% industrial pure aluminum, Al-20Ce, Al-10Ni, and Al-5Yb master alloys.

[0029] Unless otherwise specified, all instruments, equipment and raw materials involved in the following embodiments and comparative examples can be obtained through legitimate commercial channels.

[0030] Unless otherwise specified, the experimental and testing methods in the following embodiments and comparative examples are conventional experimental and testing methods of the prior art. Among them, the room temperature tensile test was performed in accordance with GB / T228.1-2010, and the high temperature tensile test was performed in accordance with GB / T228.2-2015.

[0031] Example 1

[0032] 1) According to the weight percentage of the constituent elements, take Ce: 11 wt%, Ni: 2.5 wt%, Yb: 0.15 wt%, and the balance is Al; first clean the above raw materials, and then place them in a drying oven and preheat at 210℃ for 30 minutes;

[0033] 2) Place industrial pure aluminum into a graphite crucible in a melting furnace at a melting temperature of 790℃. After the industrial pure aluminum has completely melted, add preheated Al-20Ce master alloy, Al-10Ni master alloy, and Al-5Yb master alloy. After all the raw materials have melted, lower the furnace temperature to 750℃ and then perform electromagnetic stirring for 8 minutes at a frequency of 35 Hz.

[0034] 3) After electromagnetic stirring is completed, dry high-purity argon gas is introduced into the melt for degassing and refining. The argon gas flow rate is 0.7 L / min and the refining time is 5 min. After refining, slag is removed and filtered, and the melt is kept at 740℃ for 10 min.

[0035] 4) The melt is then poured into a cast iron mold, cooled to room temperature, and then demolded to obtain an alloy ingot.

[0036] Example 2

[0037] 1) According to the weight percentage of the constituent elements, Ce: 11.5 wt%, Ni: 3 wt%, Yb: 0.2 wt%, with the balance being Al. First, clean the above raw materials thoroughly, then place them in a drying oven and preheat at 210℃ for 30 minutes;

[0038] 2) Place industrial pure aluminum into a graphite crucible in a melting furnace at a melting temperature of 790℃. After the industrial pure aluminum has completely melted, add preheated Al-20Ce master alloy, Al-10Ni master alloy, and Al-5Yb master alloy. After all the raw materials have melted, lower the furnace temperature to 750℃ and then perform electromagnetic stirring for 8 minutes at a frequency of 35 Hz.

[0039] 3) After electromagnetic stirring is completed, dry high-purity argon gas is introduced into the melt for degassing and refining. The argon gas flow rate is 0.7 L / min and the refining time is 5 min. After refining, slag is removed and filtered, and the melt is kept at 740℃ for 10 min.

[0040] 4) The melt is then poured into a cast iron mold, cooled to room temperature, and then demolded to obtain an alloy ingot.

[0041] Example 3

[0042] 1) According to the weight percentage of the constituent elements, take Ce: 12 wt%, Ni: 3 wt%, Yb: 0.3 wt%, and the balance is Al; first clean the above raw materials, and then place them in a drying oven and preheat at 210℃ for 30 minutes;

[0043] 2) Place industrial pure aluminum into a graphite crucible in a melting furnace at a melting temperature of 800℃. After the industrial pure aluminum has completely melted, add preheated Al-20Ce master alloy, Al-10Ni master alloy, and Al-5Yb master alloy. After all the raw materials have melted, lower the furnace temperature to 760℃ and then perform electromagnetic stirring for 8 minutes at a frequency of 35 Hz.

[0044] 3) After electromagnetic stirring is completed, dry high-purity argon gas is introduced into the melt for degassing and refining. The argon gas flow rate is 0.7 L / min and the refining time is 5 min. After refining, slag is removed and filtered, and the melt is kept at 750℃ for 10 min.

[0045] 4) The melt is then poured into a cast iron mold, cooled to room temperature, and then demolded to obtain an alloy ingot.

[0046] Example 4

[0047] 1) According to the weight percentage of the constituent elements, take Ce: 13 wt%, Ni: 3.5 wt%, Yb: 0.3 wt%, and the balance is Al. First, clean the above raw materials, and then place them in a drying oven and preheat at 210℃ for 30 minutes;

[0048] 2) Place industrial pure aluminum into a graphite crucible in a melting furnace at a melting temperature of 800℃. After the industrial pure aluminum has completely melted, add preheated Al-20Ce master alloy, Al-10Ni master alloy, and Al-5Yb master alloy. After all the raw materials have melted, lower the furnace temperature to 760℃ and then perform electromagnetic stirring for 8 minutes at a frequency of 35 Hz.

[0049] 3) After electromagnetic stirring is completed, dry high-purity argon gas is introduced into the melt for degassing and refining. The argon gas flow rate is 0.7 L / min and the refining time is 5 min. After refining, slag is removed and filtered, and the melt is kept at 750℃ for 10 min.

[0050] 4) The melt is then poured into a cast iron mold, cooled to room temperature, and then demolded to obtain an alloy ingot.

[0051] Example 5

[0052] 1) According to the weight percentage of the constituent elements, Ce: 12 wt%, Ni: 4 wt%, Yb: 0.2 wt%, with the balance being Al. First, clean the above raw materials thoroughly, then place them in a drying oven and preheat at 210℃ for 30 minutes;

[0053] 2) Place industrial pure aluminum into a graphite crucible in a melting furnace at a melting temperature of 800℃. After the industrial pure aluminum has completely melted, add preheated Al-20Ce master alloy, Al-10Ni master alloy, and Al-5Yb master alloy. After all the raw materials have melted, lower the furnace temperature to 760℃ and then perform electromagnetic stirring for 8 minutes at a frequency of 35 Hz.

[0054] 3) After electromagnetic stirring is completed, dry high-purity argon gas is introduced into the melt for degassing and refining. The argon gas flow rate is 0.7 L / min and the refining time is 5 min. After refining, slag is removed and filtered, and the melt is kept at 750℃ for 10 min.

[0055] 4) The melt is then poured into a cast iron mold, cooled to room temperature, and then demolded to obtain an alloy ingot.

[0056] The ternary eutectic structure diagram of the alloy is as follows: Figure 1 As shown.

[0057] Comparative Example 1

[0058] 1) According to the weight percentage of the constituent elements, Ce: 11 wt%, with the balance being Al; first clean the above raw materials, then place them in a drying oven and preheat at 210℃ for 30 minutes;

[0059] 2) Place industrial pure aluminum into a graphite crucible in a melting furnace and melt it at a temperature of 770°C. After the industrial pure aluminum has completely melted, add the preheated Al-20Ce master alloy. After all the raw materials have melted, lower the furnace temperature to 750°C and then perform electromagnetic stirring for 8 minutes at a frequency of 35 Hz.

[0060] 3) After electromagnetic stirring is completed, dry high-purity argon gas is introduced into the melt for degassing and refining. The argon gas flow rate is 0.7 L / min and the refining time is 5 min. After refining, slag is removed and filtered, and the melt is kept at 740℃ for 10 min.

[0061] 4) The melt is then poured into a cast iron mold, cooled to room temperature, and then demolded to obtain an alloy ingot.

[0062] Comparative Example 2

[0063] 1) According to the weight percentage of the constituent elements, Ce: 13 wt%, with the balance being Al; first clean the above raw materials, then place them in a drying oven and preheat at 210℃ for 30 minutes;

[0064] 2) Place industrial pure aluminum into a graphite crucible in a melting furnace and melt it at a temperature of 770°C. After the industrial pure aluminum has completely melted, add the preheated Al-20Ce master alloy. After all the raw materials have melted, lower the furnace temperature to 750°C and then perform electromagnetic stirring for 8 minutes at a frequency of 35 Hz.

[0065] 3) After electromagnetic stirring is completed, dry high-purity argon gas is introduced into the melt for degassing and refining. The argon gas flow rate is 0.7 L / min and the refining time is 5 min. After refining, slag is removed and filtered, and the melt is kept at 740℃ for 10 min.

[0066] 4) The melt is then poured into a cast iron mold, cooled to room temperature, and then demolded to obtain an alloy ingot.

[0067] The SEM image of the eutectic structure of the alloy is shown below. Figure 2 As shown.

[0068] Comparative Example 3

[0069] 1) According to the weight percentage of the constituent elements, take Ce: 12 wt%, Ni: 1 wt%, Yb: 1.5 wt%, and the balance is Al; first clean the above raw materials, and then place them in a drying oven and preheat at 210℃ for 30 minutes;

[0070] 2) Place industrial pure aluminum into a graphite crucible in a melting furnace at a melting temperature of 780℃; after the industrial pure aluminum has completely melted, add preheated Al-20Ce master alloy, Al-10Ni master alloy, and Al-5Yb master alloy. After all the raw materials have melted, lower the furnace temperature to 760℃ and then perform electromagnetic stirring for 8 minutes at a frequency of 35 Hz.

[0071] 3) After electromagnetic stirring is completed, dry high-purity argon gas is introduced into the melt for degassing and refining. The argon gas flow rate is 0.7 L / min and the refining time is 5 min. After refining, slag is removed and filtered, and the melt is kept at 740℃ for 10 min.

[0072] 4) The melt is then poured into a cast iron mold, cooled to room temperature, and then demolded to obtain an alloy ingot.

[0073] Comparative Example 4

[0074] 1) According to the weight percentage of the constituent elements, take Ce: 12 wt%, Ni: 3 wt%, and the balance Al; first clean the above raw materials, and then place them in a drying oven and preheat at 210℃ for 30 minutes;

[0075] 2) Place industrial pure aluminum into a graphite crucible in a melting furnace at a melting temperature of 790℃. After the industrial pure aluminum has completely melted, add preheated Al-20Ce master alloy and Al-10Ni master alloy. After all the raw materials have melted, lower the furnace temperature to 760℃ and then perform electromagnetic stirring for 8 minutes at a frequency of 35 Hz.

[0076] 3) After electromagnetic stirring is completed, dry high-purity argon gas is introduced into the melt for degassing and refining. The argon gas flow rate is 0.7 L / min and the refining time is 5 min. After refining, slag is removed and filtered, and the melt is kept at 740℃ for 10 min.

[0077] 4) The melt is then poured into a cast iron mold, cooled to room temperature, and then demolded to obtain an alloy ingot.

[0078] Performance testing

[0079] The alloys prepared in each embodiment and comparative example were subjected to room temperature tensile and high temperature tensile tests. The elemental composition of Ce, Ni and Yb in each example is shown in Table 1 below. The rest are Al and unavoidable impurity elements, and the amount of impurities does not exceed 0.1 wt%.

[0080] Table 1

[0081]

[0082] The room temperature tensile and high temperature tensile properties of Examples 1-5 and Comparative Examples 1-4 were tested according to GB / T 228.1-2010 and GB / T 228.2-2015 standards. The performance test results are shown in Table 2.

[0083] Table 2

[0084]

[0085] As shown in Table 2, the room temperature and high temperature mechanical properties of the alloy prepared in this invention are significantly improved compared to the comparative example. This is because the addition of Ni forms finely spaced fibrous α-Al / Al... 11 Ce3 / Al3Ni ternary eutectic and Chinese character-shaped α-Al / Al 11 The mixed microstructure of the Ce3 eutectic results in a eutectic phase volume fraction exceeding 20%, leading to more pronounced second-phase strengthening and load transfer effects, thus improving the alloy's mechanical properties. This dual-state eutectic structure at different scales is beneficial for regulating the alloy's strain distribution and enhancing its plasticity. Furthermore, the addition of Yb refines the primary Al... 11 The Ce3 phase was introduced, which caused its morphology to transform into a fine blocky structure and also refined the α-Al / Al phase. 11The Ce3 eutectic spacing further improves the overall mechanical properties of the alloy. The eutectic phases of the prepared Al-Ce-Ni alloy all exhibit low coarsening rates, which is beneficial for strengthening the matrix at high temperatures.

[0086] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions without departing from the concept of the present invention are all within the protection scope of the present invention.

Claims

1. An Al-Ce-Ni alloy with a dual-state eutectic structure, characterized in that, The alloy, by mass percentage, comprises: Ce 11–13%, Ni 2.5–4%, Yb 0.1–0.3%, with the balance being Al and unavoidable impurity elements. The mass ratio of Ce to Ni is (3–5):

1. Its microstructure consists of α-Al / Al groups in the shape of Chinese characters. 11 Ce3 binary eutectic and fine fibrous α-Al / Al 11 The ternary eutectic consists of two morphologies of Ce3 / Al3Ni.

2. The Al-Ce-Ni alloy according to claim 1, characterized in that, The alloy has the following composition by mass percentage: Ce 12%, Ni 3%, Yb 0.3%, with the balance being Al and unavoidable impurity elements.

3. The Al-Ce-Ni alloy according to claim 1, characterized in that, The unavoidable impurity element content is ≤0.1% by mass percentage.

4. The Al-Ce-Ni alloy according to claim 1, characterized in that, The Al-Ce-Ni alloy has a eutectic phase volume fraction of not less than 20%, a yield strength of 132–151 MPa at room temperature, a tensile strength of 244–257 MPa, and an elongation of 5.3–7.5%.

5. The method for preparing the Al-Ce-Ni alloy according to any one of claims 1 to 4, characterized in that, Includes the following steps: 1) Batching: Weigh out aluminum raw materials, Ce raw materials, Ni raw materials, and Yb raw materials according to the proportions, clean them thoroughly, and preheat them; 2) Smelting: Heat the preheated aluminum raw material to 790-810℃. After the aluminum raw material is completely melted, add the preheated Ce, Ni and Yb raw materials. After melting, cool down to 750-760℃ and stir for 6-10 minutes. 3) Refining: After stirring, degassing and refining are carried out in the absence of air, slag is removed and filtered, and the temperature is held at 740-750℃ for 8-10 minutes. The alloy ingot is then cast and demolded.

6. The preparation method according to claim 5, characterized in that, The preheating temperature in step 1) is 200-230℃, and the preheating time is 30-35 minutes.

7. The preparation method according to claim 5, characterized in that, The refining time in step 3) is 5 to 7 minutes.

8. The preparation method according to claim 5, characterized in that, The Ce raw material is an Al-20Ce alloy, the Ni raw material is an Al-10Ni alloy, and the Yb raw material is an Al-5Yb master alloy.

9. The application of the Al-Ce-Ni alloy according to any one of claims 1 to 4 in the preparation of structural parts.

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