High-strength heat-resistant aluminum alloy as well as preparation method and application thereof

Abstract

The invention relates to a high-strength heat-resistant aluminum alloy and a preparation method and application thereof, and belongs to the technical field of alloy preparation, and the preparation method comprises the following steps: S1, smelting: putting raw materials containing an aluminum element, a cerium element, a nickel element, a zirconium element and a calcium element into a smelting furnace, heating and melting, and uniformly stirring to obtain an alloy melt; s2, refining and degassing: adding a refining agent into the alloy melt, uniformly stirring, and then refining for multiple times to obtain an aluminum melt; s3, standing and slagging-off are conducted, specifically, a fluxing medium is evenly placed on the surface of the aluminum melt, slagging-off is conducted, and the pure aluminum melt is obtained; s4, pouring the test bar: pouring the pure aluminum melt through a mold; the alloy room temperature strength and high temperature resistance are well matched through a multi-element eutectic phase, and the Al-Ce-Ni series alloy of a ternary eutectic structure composed of alpha-Al, Al-Ce (Ca) and Al-Ni phases is prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy preparation, and specifically refers to a high-strength heat-resistant aluminum alloy, a preparation method thereof, and an application thereof. Background Art

[0002] The Al-Ce alloy has good fluidity and good casting performance. Although Ce is a rare earth element, the price of Ce is relatively low compared with other rare earth elements, and it will not significantly increase the cost as the main element of the aluminum alloy. The strengthening ability of the Al-Ce3 binary eutectic phase in the existing Al-Ce alloy is weak, and alloying is required to regulate the eutectic structure and improve the mechanical properties and heat resistance of the alloy. The existing Al-Ce-Ni alloy introduces a ternary eutectic structure through Ni, but there is still room for improvement in high-temperature stability and plasticity. It is necessary to further refine the grains and improve the room-temperature and high-temperature properties of the alloy to meet the application requirements in fields such as aerospace, automobiles, and ships. 11 The strengthening ability of the Ce3 binary eutectic phase in the existing Al-Ce alloy is weak, and alloying is required to regulate the eutectic structure and improve the mechanical properties and heat resistance of the alloy. The existing Al-Ce-Ni alloy introduces a ternary eutectic structure through Ni, but there is still room for improvement in high-temperature stability and plasticity. It is necessary to further refine the grains and improve the room-temperature and high-temperature properties of the alloy to meet the application requirements in fields such as aerospace, automobiles, and ships. Summary of the Invention

[0003] In order to overcome some of the problems mentioned in the above background, the present invention provides a preparation method of a high-strength heat-resistant aluminum alloy to at least partially solve the above problems.

[0004] According to the technical solution of the present invention, a preparation method of a high-strength heat-resistant aluminum alloy is provided, including the following steps:

[0005] S1. Melting: Placing raw materials containing aluminum element, cerium element, nickel element, zirconium element, and calcium element in a furnace for heating and melting, and then stirring evenly to obtain an alloy melt;

[0006] S2. Refining and degassing: Adding a refining agent to the alloy melt and stirring evenly, and then performing multiple refinings to obtain an aluminum melt;

[0007] S3. Standing and skimming: Uniformly placing a slagging agent on the surface of the aluminum melt, and skimming to obtain a pure aluminum melt;

[0008] S4. Pouring test bars: Pouring the pure aluminum melt through a mold.

[0009] Further, the raw materials include pure aluminum ingots, aluminum-cerium master alloys, aluminum-nickel master alloys, aluminum-zirconium master alloys, and aluminum-calcium master alloys.

[0010] Further, the raw materials include 6-10 wt.% of cerium, 3-5 wt.% of nickel, 0.1-0.5 wt.% of zirconium, 0.2-0.4 wt.% of calcium, and the rest is aluminum.

[0011] Further, the raw materials include 7-9 wt.% of cerium, 3-5 wt.% of nickel, 0.2-0.4 wt.% of zirconium, 0.2-0.4 wt.% of calcium, and the rest is aluminum.

[0012] Further, after being evenly stirred in the step S1, the temperature is raised to 800-850 °C and kept warm for 5-10 min.

[0013] Further, the refining agent in the step S2 includes one of sodium fluoride, cryolite, or a mixture of sodium fluoride and sodium chloride;

[0014] The temperature of the refining is 720-760 °C, and the refining time is 10-20 min.

[0015] Further, the drossing agent in the step S3 includes one of sodium nitrate, potassium nitrate, sodium chloride, potassium chloride, or quartz sand;

[0016] The drossing agent is evenly sprinkled on the surface of the aluminum melt, and after standing for 10-20 min, the surface scum is removed to obtain a pure aluminum alloy melt, and the temperature is maintained at 720-760 °C during the drossing process.

[0017] Further, the S1 includes: putting pure aluminum ingots, aluminum cerium master alloy, aluminum nickel master alloy, aluminum zirconium master alloy, and aluminum calcium master alloy into a furnace for heating, fully melting and stirring them evenly, and then continuing to heat to 800-850 °C and keeping warm for 5-10 min.

[0018] Further, the present invention also provides a high-strength heat-resistant aluminum alloy: the high-strength heat-resistant aluminum alloy prepared by the above method.

[0019] Furthermore, the present invention also provides an application of the high-strength heat-resistant aluminum alloy, applying the above high-strength heat-resistant aluminum alloy in the fields of aerospace and automotive ships.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The present invention realizes a good match between the room temperature strength and high-temperature resistance of the alloy through a multi-component eutectic phase, and prepares an Al-Ce-Ni series alloy with a ternary eutectic structure composed of α-Al, Al-Ce(Ca), and Al-Ni phases.

[0022] (2) The room temperature tensile strength of the aluminum alloy prepared by the present invention is not less than 320 MPa, the elongation is not less than 3%, the high-temperature tensile strength at 250 °C is not less than 150 MPa, and the high-temperature tensile strength at 300 °C is not less than 100 MPa. Description of the Drawings

[0023] Figure 1 is the SEM micrograph of the microstructure of the aluminum alloy prepared in Example 3 in the embodiments of the present invention;

[0024] Figure 2It is the SEM micrograph of the aluminum alloy prepared in Comparative Example 1 in the embodiments of the present invention;

[0025] Figure 3 It is the SEM micrograph of the aluminum alloy prepared in Comparative Example 2 in the embodiments of the present invention. Detailed implementation manners

[0026] Next, the technical solutions in the embodiments will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection.

[0027] This technology overcomes the deficiencies of the prior art, solves the problem that existing heat-resistant aluminum alloys can only work below 200°C, provides a high-strength heat-resistant Al-Ce-Ni alloy material containing Ca and Zr and its preparation method, so that it has good mechanical properties at room temperature and high temperature.

[0028] Specifically, the embodiments of the present invention provide a preparation method for a high-strength heat-resistant aluminum alloy, including the following steps:

[0029] S1. Melting: Placing raw materials containing aluminum element, cerium element, nickel element, zirconium element and calcium element in a furnace for heating and melting, and then stirring evenly to obtain an alloy melt;

[0030] S2. Refining and degassing: Adding a refining agent to the alloy melt and stirring evenly, and then performing multiple refinings to obtain an aluminum melt;

[0031] S3. Standing and skimming: Uniformly placing a drossing agent on the surface of the aluminum melt, and skimming to obtain a pure aluminum melt;

[0032] S4. Pouring test bars: Pouring the pure aluminum melt through a mold.

[0033] It should be noted that: in step S4, the pure aluminum melt is poured into a preheated mold at 740°C. The preheating temperature of the mold is 300°C. The preheating at 300°C reduces the temperature difference between the melt and the mold, avoids cracks or shrinkage porosity caused by rapid cooling, and at the same time controls the solidification rate to refine the grains. The pouring temperature of 740°C ensures the fluidity of the melt, prevents defects such as incomplete pouring or cold shut, so as to obtain a Ca / Zr-strengthened Al-Ce-Ni alloy with dense structure and uniform composition, optimize the grain boundary structure, and improve the mechanical properties of the material at room temperature and high temperature; through the combined addition of calcium element and zirconium element, the ternary eutectic structure in the alloy is refined, and the calcium element is dissolved into the ternary eutectic phase, further improving the thermal stability of the aluminum alloy.

[0034] In a further embodiment of this example, the raw materials include pure aluminum ingots, aluminum cerium master alloy, aluminum nickel master alloy, aluminum zirconium master alloy, and aluminum calcium master alloy. Master alloys such as aluminum cerium master alloy and aluminum nickel master alloy are formed by pre - combining refractory metals with aluminum to reduce the difficulty of directly adding refractory metals to pure aluminum, avoid problems such as local composition segregation and excessive melting temperature, improve the melt composition uniformity of the master alloy, and reduce the burning loss of alloying elements.

[0035] In a further embodiment of this example, the raw materials include 6 - 10 wt.% of cerium, 3 - 5 wt.% of nickel, 0.1 - 0.5 wt.% of zirconium, 0.2 - 0.4 wt.% of calcium, and the balance is aluminum.

[0036] In a further embodiment of this example, the raw materials include 7 - 9 wt.% of cerium, 3 - 5 wt.% of nickel, 0.2 - 0.4 wt.% of zirconium, 0.2 - 0.4 wt.% of calcium, and the balance is aluminum.

[0037] In a further embodiment of this example, after stirring evenly in step S1, the temperature is raised to 800 - 850 °C and held for 5 - 10 min to promote the full diffusion of alloying elements, eliminate dendritic segregation therein, and at the same time completely dissolve refractory metals in the aluminum matrix to form a uniform solid solution. High - temperature holding ensures the effective solid solution of alloying elements, laying a foundation for the formation of subsequent strengthening phases.

[0038] In a further embodiment of this example, the refining agent in step S2 includes one of sodium fluoride, cryolite, or a mixture of sodium fluoride and sodium chloride;

[0039] The refining temperature is 720 - 760 °C, and the refining time is 10 - 20 min; the refining agent reacts with the melt to generate gases (such as chlorine gas, carbon dioxide), adsorbs hydrogen and inclusions through bubbles and floats them out to purify the melt. In the temperature range of 720 - 760 °C, it ensures the full progress of the refining reaction, and at the same time avoids overheating of the melt, resulting in oxidation or volatilization of alloying elements, so as to achieve the effects of reducing the hydrogen content in the melt, reducing the porosity defects of castings, removing inclusions, and improving the material density and mechanical properties.

[0040] In a further embodiment of this example, the drossing agent in step S3 includes one of sodium nitrate, potassium nitrate, sodium chloride, potassium chloride, or quartz sand;

[0041] Sprinkle the drossing agent evenly on the surface of the aluminum melt. After standing for 10 - 20 minutes, skim off the surface dross to obtain a pure aluminum alloy melt. During the dross skimming process, maintain the temperature at 720 - 760°C; the covering agent adsorbs the surface oxides of the pure aluminum alloy melt to form a slag layer that is easily peeled off; standing for 10 minutes promotes the further floating and aggregation of minute inclusions. Maintaining 720 - 760°C ensures the fluidity of the melt, avoiding secondary mixing of impurities during dross skimming, so as to significantly reduce the inclusion content, improve the purity of the melt, reduce the crack sources in subsequent processing, and improve the fatigue life of the material.

[0042] In a further embodiment of this example, S1 includes: putting pure aluminum ingots, aluminum - cerium master alloy, aluminum - nickel master alloy, aluminum - zirconium master alloy, and aluminum - calcium master alloy into a furnace for heating. After complete melting, fully stir and mix them evenly, and continue heating to 800 - 850°C, and keep the temperature for 5 - 10 minutes.

[0043] On the other hand, the embodiment of the present invention also provides a high - strength heat - resistant aluminum alloy: the high - strength heat - resistant aluminum alloy prepared by the above method.

[0044] On the other hand, the embodiment of the present invention also provides an application of the high - strength heat - resistant aluminum alloy, applying the above high - strength heat - resistant aluminum alloy in the fields of aerospace and automotive and marine.

[0045] Example 1

[0046] Smelting: Put pure aluminum ingots, Al - Ce master alloy, Al - Ni master alloy, Al - Zr master alloy, and Al - Ca master alloy into a furnace for heating. After complete melting, fully stir to make them mix evenly, and continue heating to 800°C, and keep the temperature for 10 minutes; among them, cerium is 6wt.%, nickel is 3wt.%, zirconium is 0.1wt.%, calcium is 0.2wt.%, and the rest is aluminum.

[0047] Refining and degassing: Add a refining agent, press it into the melt with a bell jar and fully stir. Control the refining temperature at 740°C, refine multiple times, and the refining time is 20 minutes;

[0048] Standing and dross skimming: After degassing, evenly sprinkle the drossing agent on the surface of the aluminum melt, stand for 10 minutes, and skim off the surface dross to obtain a pure aluminum alloy melt. The temperature during this process is controlled at about 740°C;

[0049] Casting test bars: Pour the aluminum melt into a pre - heated mold at 740°C. The pre - heating temperature of the mold is 300°C to obtain a high - strength heat - resistant aluminum alloy.

[0050] Example 2

[0051] Smelting: Put pure aluminum ingots, Al-Ce master alloy, Al-Ni master alloy, Al-Zr master alloy, and Al-Ca master alloy into a furnace and heat them until they are completely melted. Then stir them thoroughly to make them evenly mixed. Continue heating to 800 °C and keep it warm for 10 min. Among them, cerium is 7 wt.%, nickel is 4 wt.%, zirconium is 0.2 wt.%, calcium is 0.3 wt.%, and the rest is aluminum.

[0052] Refining and degassing: Add a refining agent and press it into the melt under the surface with a bell jar and stir thoroughly. Control the refining temperature at 740 °C and refine it multiple times for 20 min.

[0053] Static settling and slag skimming: After degassing, evenly sprinkle a slagging agent on the surface of the aluminum melt, let it stand for 10 min, and skim off the surface scum to obtain a pure aluminum alloy melt. Control the temperature at about 740 °C during this process.

[0054] Casting test bars: Pour the aluminum melt into a preheated mold at 740 °C. The preheating temperature of the mold is 300 °C to obtain a high-strength heat-resistant aluminum alloy.

[0055] Example 3

[0056] Smelting: Put pure aluminum ingots, Al-Ce master alloy, Al-Ni master alloy, Al-Zr master alloy, and Al-Ca master alloy into a furnace and heat them until they are completely melted. Then stir them thoroughly to make them evenly mixed. Continue heating to 800 °C and keep it warm for 10 min. Among them, cerium is 8 wt.%, nickel is 4 wt.%, zirconium is 0.2 wt.%, calcium is 0.3 wt.%, and the rest is aluminum.

[0057] Refining and degassing: Add a refining agent and press it into the melt under the surface with a bell jar and stir thoroughly. Control the refining temperature at 740 °C and refine it multiple times for 20 min.

[0058] Static settling and slag skimming: After degassing, evenly sprinkle a slagging agent on the surface of the aluminum melt, let it stand for 10 min, and skim off the surface scum to obtain a pure aluminum alloy melt. Control the temperature at about 740 °C during this process.

[0059] Casting test bars: Pour the aluminum melt into a preheated mold at 740 °C. The preheating temperature of the mold is 300 °C to obtain a high-strength heat-resistant aluminum alloy.

[0060] Example 4

[0061] Smelting: Put pure aluminum ingots, Al-Ce master alloy, Al-Ni master alloy, Al-Zr master alloy, and Al-Ca master alloy into a furnace and heat them until they are completely melted. Then stir them thoroughly to make them evenly mixed, continue heating to 800 °C, and keep warm for 10 min. Among them, cerium is 9 wt.%, nickel is 5 wt.%, zirconium is 0.3 wt.%, calcium is 0.4 wt.%, and the rest is aluminum.

[0062] Refining and degassing: Add a refining agent and press it into the melt under the surface with a bell jar and stir thoroughly. Control the refining temperature at 740 °C and refine multiple times for 20 min.

[0063] Standing and skimming: After degassing, evenly sprinkle a drossing agent on the surface of the aluminum melt, let it stand for 10 min, and skim off the surface scum to obtain a pure aluminum alloy melt. The temperature during this process is controlled at about 740 °C.

[0064] Casting test bars: Pour the aluminum melt into a preheated mold at 740 °C. The preheating temperature of the mold is 300 °C to obtain a high-strength heat-resistant aluminum alloy.

[0065] Example 5

[0066] Smelting: Put pure aluminum ingots, Al-Ce master alloy, Al-Ni master alloy, Al-Zr master alloy, and Al-Ca master alloy into a furnace and heat them until they are completely melted. Then stir them thoroughly to make them evenly mixed, continue heating to 800 °C, and keep warm for 10 min. Among them, cerium is 10 wt.%, nickel is 5 wt.%, zirconium is 0.5 wt.%, calcium is 0.4 wt.%, and the rest is aluminum.

[0067] Refining and degassing: Add a refining agent and press it into the melt under the surface with a bell jar and stir thoroughly. Control the refining temperature at 740 °C and refine multiple times for 20 min.

[0068] Standing and skimming: After degassing, evenly sprinkle a drossing agent on the surface of the aluminum melt, let it stand for 10 min, and skim off the surface scum to obtain a pure aluminum alloy melt. The temperature during this process is controlled at about 740 °C.

[0069] Casting test bars: Pour the aluminum melt into a preheated mold at 740 °C. The preheating temperature of the mold is 300 °C to obtain a high-strength heat-resistant aluminum alloy.

[0070] Comparative Example 1

[0071] Smelting: Put pure aluminum ingots, Al-Ce master alloy, and Al-Ni master alloy into a furnace and heat them until they are completely melted. Then stir them thoroughly to make them evenly mixed, continue heating to 800 °C, and keep warm for 10 min. Among them, cerium is 8 wt.%, nickel is 4 wt.%, and the rest is aluminum.

[0072] Refining and degassing: Add a refining agent, press it into the melt with a bell jar and stir well. Control the refining temperature at 740°C, refine multiple times, and the refining time is 20 minutes;

[0073] Static standing and skimming: After degassing, evenly sprinkle a slagging agent on the surface of the aluminum melt, let it stand for 10 minutes, and skim off the surface scum to obtain a pure aluminum alloy melt. The temperature during this process is controlled at about 740°C;

[0074] Casting test bars: Pour the aluminum melt into a preheated mold at 740°C. The preheating temperature of the mold is 300°C to obtain a high-strength heat-resistant aluminum alloy.

[0075] Comparative Example 2

[0076] Melting: Put pure aluminum ingots, Al-Ce master alloy, Al-Ni master alloy, and Al-Zr master alloy into a furnace and heat them until they are completely melted. Stir well to make them mix evenly, and continue heating to 800°C and hold for 10 minutes; among them, cerium is 6 wt.%, nickel is 3 wt.%, zirconium is 0.4 wt.%, and the rest is aluminum.

[0077] Refining and degassing: Add a refining agent, press it into the melt with a bell jar and stir well. Control the refining temperature at 740°C, refine multiple times, and the refining time is 20 minutes;

[0078] Static standing and skimming: After degassing, evenly sprinkle a slagging agent on the surface of the aluminum melt, let it stand for 10 minutes, and skim off the surface scum to obtain a pure aluminum alloy melt. The temperature during this process is controlled at about 740°C;

[0079] Casting test bars: Pour the aluminum melt into a preheated mold at 740°C. The preheating temperature of the mold is 300°C to obtain a high-strength heat-resistant aluminum alloy.

[0080] Samples of the aluminum alloys prepared in Examples 1-5 were respectively taken for testing of room-temperature tensile strength, elongation, and high-temperature tensile properties. Its room-temperature tensile strength is not less than 320 MPa, the elongation is not less than 3%, the high-temperature tensile strength at 250°C is not less than 150 MPa, and the high-temperature tensile strength at 300°C is not less than 100 MPa.

[0081] Samples of the aluminum alloys prepared in Example 3, Comparative Example 1, and Comparative Example 2 were taken to collect their microscopic morphology images by a scanning electron microscope (SEM). The results are as Figures 1 - 3 shown, Figure 1 Compared with Figure 2 and Figure 3 the eutectic structure is significantly refined, and there is no obvious Chinese character-shaped Al-Ce eutectic structure in Figure 1 Figure 3 ​The proportion of the eutectic structure exceeds 40%. Therefore, by the combined addition of calcium and zirconium elements, the ternary eutectic structure in the alloy can be refined, and the calcium element dissolves into the eutectic phase, which can further improve the thermal stability of the phase.

[0082] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a high-strength heat-resistant aluminum alloy, characterized in that, It includes the following steps: S1. Melting: Place the raw materials containing aluminum, cerium, nickel, zirconium, and calcium elements in a furnace, heat and melt them, and then stir evenly to obtain an alloy melt. S2. Refining and degassing: Add a refining agent to the alloy melt and stir evenly, and then perform multiple refinings to obtain an aluminum melt. S3. Standing and slag skimming: Evenly place a slagging agent on the surface of the aluminum melt, and perform slag skimming to obtain a pure aluminum melt. S4. Casting test bars: Cast the pure aluminum melt through a mold.

2. The preparation method of the high-strength heat-resistant aluminum alloy according to claim 1, characterized in that, The raw materials include pure aluminum ingots, aluminum-cerium master alloy, aluminum-nickel master alloy, aluminum-zirconium master alloy, and aluminum-calcium master alloy.

3. The preparation method of the high-strength heat-resistant aluminum alloy according to claim 1, characterized in that, The raw materials include 6-10 wt.% of cerium, 3-5 wt.% of nickel, 0.1-0.5 wt.% of zirconium, 0.2-0.4 wt.% of calcium, and the rest is aluminum.

4. The preparation method of the high-strength heat-resistant aluminum alloy according to claim 3, characterized in that The raw materials include 7-9 wt.% of cerium, 3-5 wt.% of nickel, 0.2-0.4 wt.% of zirconium, 0.2-0.4 wt.% of calcium, and the rest is aluminum.

5. The preparation method of the high-strength heat-resistant aluminum alloy according to claim 1, characterized in that, In step S1, after stirring evenly, heat up to 800-850 °C and keep warm for 5-10 min.

6. The preparation method of the high-strength heat-resistant aluminum alloy according to claim 1, wherein The refining agent in step S2 includes one of sodium fluoride, cryolite, or a mixture of sodium fluoride and sodium chloride. The refining temperature is 720-760 °C, and the refining time is 10-20 min.

7. The preparation method of the high-strength heat-resistant aluminum alloy according to claim 1, characterized in that, The slagging agent in step S3 includes one of sodium nitrate, potassium nitrate, sodium chloride, potassium chloride, or quartz sand. Evenly sprinkle the slagging agent on the surface of the aluminum melt, stand for 10-20 min, and then skim off the surface scum to obtain a pure aluminum alloy melt. During the slag skimming process, keep the temperature at 720-760 °C.

8. The preparation method of the high-strength heat-resistant aluminum alloy according to claim 1, characterized in that, S1 includes: Put pure aluminum ingots, aluminum-cerium master alloy, aluminum-nickel master alloy, aluminum-zirconium master alloy, and aluminum-calcium master alloy into a furnace, heat them to completely melt, fully stir and mix evenly, continue to heat to 800-850 °C, and keep warm for 5-10 min.

9. A high-strength heat-resistant aluminum alloy, characterized in that, A high-strength heat-resistant aluminum alloy prepared according to any one of claims 1-8.

10. Application of a high-strength heat-resistant aluminum alloy, characterized in that, Apply the high-strength heat-resistant aluminum alloy prepared according to any one of claims 1-8 in the fields of aerospace and automotive ships.

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