An Al-containing 10 Al-Ce-Fe alloy containing an Fe2Ce phase and a preparation method thereof

Abstract

The present invention relates to an Al-Ce-Fe alloy containing an Al 10 Fe2Ce phase and a preparation method thereof. In the Al-Ce-Fe alloy, the mass fraction of Ce is 3-5%, the mass fraction of Fe is 1-3%, and the balance is Al. By replacing the Ce element in the Al-Ce alloy with different contents of Fe element, the present invention obtains eutectic Al 11 Ce3 with a smaller lamellar spacing, needle-like and short rod-shaped Al 13 Fe4 phases with good thermal stability, and feather-like and granular Al 10 Fe2Ce phases, which are beneficial to heat resistance and hinder the dislocation movement during plastic deformation. It not only improves the room-temperature mechanical properties of the material, but also improves the high-temperature mechanical properties of the alloy. The compressive strength of the alloy at room temperature reaches 170 MPa, the compressive strength reaches 124 MPa after thermal exposure at 200 °C for 120 h, and the compressive strength reaches 93 MPa after thermal exposure at 300 °C for 120 h.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy casting, and specifically relates to an Al-Ce-Fe alloy containing Al 10 Fe2Ce phase and a preparation method thereof. Background Art

[0002] High-strength heat-resistant aluminum alloys are widely used in key components such as automotive engines and aerospace propulsion devices due to their high strength and good heat resistance. With the continuous increase in the demand for the high-temperature performance of aluminum alloy materials, improving their service temperature range while maintaining light weight and high strength is the current technical bottleneck. Improving the thermal stability is of great significance for expanding the use temperature range of aluminum alloys, especially for expanding their applications in the automotive and aerospace fields and realizing lightweight design.

[0003] Al-Ce alloys have excellent fluidity and castability. Since the solid solubility of Ce in Al is very low and the diffusion rate is slow, the Al 11 Ce3 phase in the Al-Ce binary eutectic structure is not easily decomposed and coarsened at high temperatures, which is beneficial to the high-temperature performance of the alloy. However, at room temperature, the strengthening effect of the Al 11 Ce3 phase is not obvious, and large blocks of the phase are prone to stress concentration, which damages the mechanical properties of the alloy. Therefore, it is necessary to further improve the room-temperature and high-temperature mechanical properties of Al-Ce alloys. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is how to optimize the structure of the Al 11 Ce3 phase in the Al-Ce binary eutectic structure and improve the room-temperature and high-temperature mechanical properties of the Al-Ce alloy. In this regard, the present invention provides an Al-Ce-Fe alloy containing Al 10 Fe2Ce phase and a preparation method thereof.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides an Al-Ce-Fe alloy containing Al 10 Fe2Ce phase, wherein the mass fraction of Ce in the Al-Ce-Fe alloy is 3-5%, the mass fraction of Fe is 1-3%, and the balance is Al and unavoidable impurity elements;

[0007] That is, the Al-Ce-Fe alloy is represented as Al-xCe-yFe alloy, where x = 3, 4, 5 and y = 1, 2, 3.

[0008] Preferably, when the mass fraction of Fe in the Al-Ce-Fe alloy is 1-3%, the Al-Ce-Fe alloy has feathery and / or granular Al 10 Fe2Ce phase, and skeletal eutectic Al 11 Ce3 phase; the phase spacing of the eutectic Al 11 Ce3 phase is 0.4-0.5 μm;

[0009] Preferably, when the mass fraction of Fe in the Al-Ce-Fe alloy is 2%, the Al-Ce-Fe alloy has feathery and / or granular Al 10 Fe2Ce phase, and skeletal eutectic Al 11 Ce3 phase; it also has massive primary Al 13 Fe4 phase, and short rod-shaped and / or needle-shaped eutectic Al 13 Fe4 phase;

[0010] The Al 10 Fe2Ce phase in the Al-Ce-Fe alloy is coated outside the massive primary Al 13 Fe4 phase; the size of the primary Al 13 Fe4 phase ≤ 20 μm; the phase spacing of the eutectic Al 11 Ce3 phase is 0.4-0.5 μm;

[0011] More preferably, the size of the primary Al 13 Fe4 phase ≤ 12 μm.

[0012] Among them, the strengthening phase of the Al-5Ce alloy is the skeletal eutectic Al 11 Ce3 phase. After adding Fe element, there are L→α-Al 初 , L→Al+Al 13 Fe4, L+Al 13 Fe4→Al+Al 10 Fe2Ce and L→Al+Al 10 Fe2Ce+Al 11 Ce3 transformations during the crystallization process of the Al-xCe-yFe alloy. Therefore, the skeletal eutectic Al 11 Ce3 phase, feathery and granular Al 10 Fe2Ce phase all exist in the Al-xCe-yFe alloy structure. Among them, the eutectic Al 13 Fe4 phase in the Al-xCe-1Fe alloy is all transformed into Al 10 Fe2Ce during the peritectic reaction, and its strengthening phases are mainly Al 11 Ce3 phase and Al 10The Fe2Ce phase. In the Al-xCe-2Fe alloy, not only a small amount of massive primary crystal Al exists 13 but also eutectic Al in the shape of needles and short rods 13 and the Fe4 phase. In the Al-3Ce-3Fe alloy, there are a large number of long needle-shaped primary crystal Al 13 and the Fe4 phase.

[0013] Al 13 The Fe4 phase has excellent high-temperature stability and can improve the strength of the alloy. However, the sharp edges and corners of the massive and long needle-shaped primary crystal Al 13 and the Fe4 phase will cause a splitting effect on the matrix, easily generating cracks and greatly reducing the mechanical properties of the alloy. In the Al-xCe-2Fe alloy within the composition range provided by the present invention, during the crystallization process, there is a peritectic eutectic transformation of L+Al 13 Fe4→Al+Al 10 Fe2Ce, and due to the incomplete peritectic eutectic transformation, an Al 10 Fe2Ce phase-coated massive and long needle-shaped primary crystal Al 13 and the Fe4 phase structure is formed. The edges and corners of this structure are relatively rounded, which not only reduces the splitting effect of the massive and long needle-shaped primary crystal Al 13 and the Fe4 phase on the matrix, but also improves the heat resistance of the alloy.

[0014] The present invention provides a preparation method for an Al-Ce-Fe alloy containing an Al 10 Fe2Ce phase, comprising the following steps:

[0015] (1) Batching: Weigh industrial pure aluminum, an Al-rich cerium mixed rare earth master alloy, and an Al-Fe master alloy according to the mass ratio of each element in the Al-Ce-Fe alloy, and set aside for later use;

[0016] (2) Melting: Heat industrial pure aluminum, an Al-rich cerium mixed rare earth master alloy, and an Al-Fe master alloy until they are completely melted to obtain an Al-Ce-Fe metal solution;

[0017] (3) Refining: Add hexachloroethane to the completely melted Al-Ce-Fe metal solution, stir evenly, skim off the surface scum, then carry out heat preservation treatment, and after heat preservation, carry out slag skimming treatment to prepare for casting;

[0018] (4) Casting: Pour the Al-Ce-Fe metal solution into a mold to obtain the product.

[0019] Preferably, in the step (1), the mass percentage of Al in the commercially pure aluminum is ≥99%; the Al-rich cerium mischmetal master alloy is an Al-10% rich cerium mischmetal master alloy, wherein the mass percentage of Ce is 7-8%, the mass percentage of La is 1-2%, and the balance is Al and other inevitable impurity elements; the mass percentage of Fe in the Al-Fe master alloy is 20%;

[0020] Among them, since La exhibits excellent strengthening and anti-coarsening properties in the Al-RE-based alloy and does not form new compounds with Fe, only replacing the Ce atoms in the Ce3 lattice of Al, it exhibits properties similar to those of Al Ce3. Therefore, the present invention uses an Al-10% rich cerium mischmetal master alloy containing La. 11 Ce3 lattice of Ce atoms, showing properties similar to those of Al 11 Ce3. Therefore, the present invention uses an Al-10% rich cerium mischmetal master alloy containing La.

[0021] Preferably, in the step (2), the heating temperature is 740-790 °C, and after reaching the target temperature, it is held for 30-50 min;

[0022] More preferably, in the step (2), the Al-Fe master alloy, the commercially pure aluminum and the Al-rich cerium mischmetal master alloy are heated simultaneously; the heating temperature is 750 °C, and after reaching the target temperature, it is held for 40 min;

[0023] Preferably, in the step (3), the mass of hexachloroethane added is 0.02%-0.05% of the mass of the Al-Ce-Fe metal solution; the stirring time after adding hexachloroethane is 2-5 min, the temperature of the heat preservation treatment is 750-800 °C, and the heat preservation time is 20-30 min;

[0024] The technical solution of the present invention has achieved the following beneficial technical effects:

[0025] The present invention replaces Ce in the Al-Ce alloy with Fe and reasonably controls the content of Fe elements in the alloy; at the same time, the preparation process conditions are further optimized, such as using an Al-10% rich cerium mischmetal master alloy containing La, adjusting the melting process and adding the refining process of hexachloroethane, etc., to achieve the purpose of improving the morphology of the eutectic Al Ce3 phase, obtaining eutectic Al Ce3 with a smaller lamellar spacing (the phase spacing is 0.4-0.5 μm), and the generated needle-like and short rod-like Al Fe4 phases and feather-like and granular Al Fe2Ce phases improve the room temperature strength of the alloy while also improving the heat resistance, and the specific analysis is as follows. 11 Ce3 phase morphology, obtaining eutectic Al 11 Ce3 (phase spacing is 0.4-0.5 μm), the generated needle-like and short rod-like Al 13 Fe4 phase and feather-like and granular Al 10 Fe2Ce phase improve the heat resistance while increasing the room temperature strength of the alloy. The specific analysis is as follows.

[0026] The mechanical properties of the alloy are improved by replacing Ce in the Al-Ce alloy with different contents of Fe. When Fe element is added, the crystallization process of the Al-Ce-Fe alloy is as follows: L→α-Al 初 、L→Al+Al 13 Fe4、L+Al 13 Fe4→Al+Al 10 Fe2Ce and L→Al+Al 10 Fe2Ce+Al 11 Ce3 transformation. As the content of Fe increases and the content of Ce decreases, the eutectic Al 11 Ce3 phase with a thick cross-section decreases, and the eutectic Al 11 Ce3 with a smaller eutectic phase spacing and smaller size increases. This eutectic Al 11 Ce3 with a smaller eutectic phase spacing and smaller size has a longer coarsening time at high temperature and higher heat resistance. And with the addition of Fe, granular and feathery Al 10 Fe2Ce phases appear. The Al 10 Fe2Ce phase has good stability and will not decompose into Al 11 Ce3 phase and Al 13 Fe4 phase at high temperature. When the replacement amount of Fe is 2%, eutectic Al 13 Fe4 phases in the form of needle flakes and short rods appear. The Al 13 Fe4 phase has good thermal stability and plays a beneficial role in improving the heat resistance of the alloy. The refinement of the Al 11 Ce3 phase, the feathery and granular Al 10 Fe2Ce phases, and the needle flake and short rod-shaped Al 13 Fe4 phases all hinder the dislocations during the plastic deformation process, making it difficult for plastic deformation, so the strength of the alloy is improved. When the replacement amount of Fe is 3%, a large number of long needle-shaped primary crystal Al 13 Fe4 phases appear in the structure, seriously splitting the matrix and greatly reducing the mechanical properties of the alloy.

[0027] In the present invention, the hardness of the Al-xCe-yFe alloy after replacing the same content of Ce with Fe is generally higher than that of the Al-5Ce alloy. The hardness of the Al-4Ce-1Fe alloy after thermal exposure at 200 °C and 300 °C for 120 hours is increased by 18.4% and 17.1% respectively compared with that of the Al-5Ce alloy. When the replacement amount of Fe in the alloy increases to 2%, the hardness reduction after thermal exposure is small. The hardness of the Al-3Ce-2Fe alloy after thermal exposure at 300 °C for 120 hours is only reduced by about 7% compared with that at room temperature. The compressive strength of the Al-4Ce-1Fe alloy after thermal exposure at 200 °C and 300 °C for 120 hours is increased by 13.8% and 8.3% respectively compared with that of the Al-5Ce alloy. The Al-xCe-2Fe alloy has higher compressive strength both at room temperature and after thermal exposure. Among them, the compressive strength of the Al-4Ce-2Fe alloy at room temperature reaches 170 MPa, the compressive strength after thermal exposure at 200 °C for 120 h reaches 124 MPa, and the compressive strength after thermal exposure at 300 °C for 120 h reaches 93 MPa. The compressive strength of Al-4Ce-2Fe at each temperature is greater than that of Al-6Ce, and the compressive strength of Al-4Ce-2Fe at room temperature is close to that of Al-10Ce, indicating that the replacement of Ce with Fe in the Al-Ce alloy ensures excellent high-temperature resistance while reducing costs and improving room-temperature strength. Description of the Drawings

[0028] Figure 1 Cooling curve and derivative curve of the cooling curve of the alloy obtained in Example 1 of the present invention;

[0029] Among them, (a) Al-5Ce, (b) Al-4Ce-1Fe, (c) Al-3Ce-2Fe, (d) Al-5Ce-1Fe, (e) Al-4Ce-2Fe;

[0030] Figure 2 Ternary phase diagram of the Al-Ce-Fe alloy in Example 1 of the present invention;

[0031] Figure 3 XRD pattern of the alloy obtained in Example 1 of the present invention;

[0032] Figure 4 Scanning electron microscope image of the alloy obtained in Example 1 of the present invention;

[0033] Among them, (a) Al-5Ce (50 μm), (b) Al-5Ce (5 μm);

[0034] (c) Al-4Ce-1Fe (50 μm), (d) Al-4Ce-1Fe (10 μm), (e) Al-4Ce-1Fe (10 μm);

[0035] (f) Al-3Ce-2Fe (50 μm), (g) Al-3Ce-2Fe (20 μm), (h) Al-3Ce-2Fe (10 μm);

[0036] (i) Al-5Ce-1Fe (50 μm), (j) Al-5Ce-1Fe (20 μm);

[0037] (k) Al-4Ce-2Fe (50 μm), (l) Al-4Ce-2Fe (20 μm), (m) Al-4Ce-2Fe (20 μm);

[0038] (n) Al-3Ce-3Fe (50 μm), (o) Al-3Ce-3Fe (20 μm);

[0039] Figure 5 Backscattered electron image of the alloy obtained in Example 1 of the present invention after deep etching;

[0040] Among them, (a) Al-5Ce (20 μm); (b) Al-4Ce-1Fe (20 μm); (c) Al-3Ce-2Fe (20 μm); (d) Al-5Ce-1Fe (20 μm); (e) Al-4Ce-2Fe (20 μm);

[0041] Figure 6 Scanning electron microscope image of the alloy obtained in Example 1 of the present invention after thermal exposure;

[0042] Among them, (a) Al-5Ce (200 °C, 50 μm); (b) Al-5Ce (300 °C, 50 μm);

[0043] (c) Al-4Ce-1Fe (200 °C, 50 μm), (d) Al-4Ce-1Fe (200 °C, 10 μm);

[0044] (e) Al-4Ce-1Fe (300 °C, 50 μm), (f) Al-4Ce-1Fe (300 °C, 20 μm);

[0045] (g) Al-3Ce-2Fe (200 °C, 50 μm), (h) Al-3Ce-2Fe (200 °C, 10 μm);

[0046] (i) Al-3Ce-2Fe (300 °C, 50 μm), (j) Al-3Ce-2Fe (300 °C, 10 μm);

[0047] (k) Al-5Ce-1Fe (200 °C, 50 μm), (l) Al-5Ce-1Fe (200 °C, 10 μm);

[0048] (m) Al-5Ce-1Fe (300 °C, 50 μm), (n) Al-5Ce-1Fe (300 °C, 10 μm);

[0049] (o) Al-4Ce-2Fe (200 °C, 50 μm), (p) Al-4Ce-2Fe (200 °C, 10 μm);

[0050] (q) Al-4Ce-2Fe (300 °C, 50 μm), (r) Al-4Ce-2Fe (300 °C, 10 μm);

[0051] Figure 7 XRD patterns of the alloy obtained in Example 1 of the present invention after thermal exposure;

[0052] Among them, (a) after thermal exposure at 200 °C; (b) after thermal exposure at 300 °C;

[0053] Figure 8 Hardness of the alloy obtained in Example 1 of the present invention before and after thermal exposure. Detailed implementation manners

[0054] The raw materials used in the following examples of the present invention: the mass percentage content of Al in industrial pure aluminum ≥ 99%; the mass percentage content of Ce in the Al-10% rich cerium mischmetal master alloy is 7.38%, the mass percentage content of La is 1.54%, the mass percentage contents of Pr, Nd and Sm are 1.04%, and the balance is Al and other inevitable impurity elements; the mass percentage content of Fe in the Al-Fe master alloy is 20%.

[0055] Example 1

[0056] An Al-Ce-Fe alloy containing 10 the Fe2Ce phase, and its preparation method includes the following steps:

[0057] (1) Batching: According to the mass ratio of each element in the Al-xCe-yFe (where x = 3, 4, 5, y = 1, 2, 3) alloy, weigh industrial pure aluminum, Al-10% rich cerium mischmetal master alloy and Al-20% Fe master alloy, cut them into small pieces, and set aside;

[0058] (2) Melting: Put industrial pure aluminum, Al-10% rich cerium mischmetal master alloy and Al-20% Fe master alloy into a graphite crucible at the same time, heat to 750 °C, keep it at the target temperature for 40 min after reaching the target temperature to completely melt it to obtain an Al-Ce-Fe metal solution;

[0059] (3)Refining: Add hexachloroethane to the Al-Ce-Fe metal solution for degassing (where the mass of hexachloroethane is 0.05% of the mass of the Al-Ce-Fe metal solution). After stirring evenly and skimming off the surface scum, keep the solution at 750 °C for 20 min, and then perform slag skimming treatment to prepare for casting;

[0060] (4)Casting: Stir the Al-Ce-Fe metal solution evenly and pour the Al-Ce-Fe metal solution into the mold to obtain the product.

[0061] Among them, using the preparation method of this embodiment, by controlling the addition amounts of industrial pure aluminum, Al-10% cerium-rich rare earth master alloy, and Al-20% Fe master alloy in step (1), Al-Ce-Fe alloys with different Ce contents, Fe contents, and Al contents are respectively prepared, specifically: Al-5Ce, Al-4Ce-1Fe, Al-3Ce-2Fe, Al-6Ce, Al-5Ce-1Fe, Al-4Ce-2Fe, Al-3Ce-3Fe (where taking Al-4Ce-2Fe as an example: the mass fraction of Ce in the alloy is 4%, the mass fraction of Fe is 2%, and the balance is Al and inevitable impurity elements, and the same applies to the rest and will not be elaborated).

[0062] Performance measurement and analysis

[0063] ① Thermal analysis: Use a thermocouple to measure the temperature during the solidification process of the alloy obtained in Example 1, and use DAQ software to collect data at a time interval of 0.01 s. Obtain the cooling curve of the alloy and the derivative curve of the cooling curve, as Figure 1 shown (in the figure, black line: cooling curve; red line: first derivative of the cooling curve; blue line: second derivative of the cooling curve). Figure 1 The corresponding meanings of the points in Figure 2 are shown in Table 1. The ternary phase diagram of the Al-Ce-Fe alloy is as Figure 1 shown. According to

[0064] Table 1 Figure 1 The corresponding meanings of the points in

[0065]

[0066] Table 2 Characteristic values of alloy crystallization

[0067]

[0068] From Figure 1 it can be seen that the crystallization process of the Al-5Ce alloy is: Point A: L→α-Al 初 ; Point G: L→Al+Al 11The crystallization process of the Ce3.Al-xCe-1Fe alloy is as follows: Point A: L→α-Al 初 ; Point D: L→Al + Al 13 Fe4; Point E: L + Al 13 Fe4→Al + Al 10 Fe2Ce; Point G: L→Al + Al 10 Fe2Ce + Al 11 Ce3; Since the Fe content in Al-xCe-1Fe is relatively low, the temperature fluctuation of the cooling curve corresponding to Point D is not obvious. From Figure 2 the ternary phase diagram, it can be seen that under equilibrium crystallization conditions, primary Al 13 Fe4 will crystallize from the liquid phase in Al-xCe-2Fe at about 680 °C. However, due to the relatively small amount of primary Al 13 Fe4 phase, the crystallization point of primary Al 13 Fe4 was not detected on the cooling curve. Since a small amount of primary Al 13 Fe4 crystallizes first during the crystallization process of the Al-xCe-2Fe alloy, the Fe content in the alloy liquid decreases. At the same time, the alloy cools at a certain cooling rate, and the crystallization region of the alloy shifts towards the Al end. Therefore, the crystallization process of the Al-xCe-2Fe alloy is as follows: Point A: L→α-Al 初 ; Point D: L→Al + Al 13 Fe4; Point E: L + Al 13 Fe4→Al + Al 10 Fe2Ce; Point G: L→Al + Al 10 Fe2Ce + Al 11 Ce3.

[0069] According to Table 2, when the Fe content is the same, the primary α-Al nucleation temperature of the alloy with a higher Ce content is lower, that is, it may form primary α-Al grains with smaller sizes. As the Fe content increases and the Ce content decreases, the eutectic growth temperature of Al-Fe increases during the Al-Fe eutectic reaction.

[0070] ② Cut the as-cast Al-Ce-Fe alloy obtained in Example 1 into samples with Φ8×12 mm using an electric spark cutting machine, polish them on sandpaper, and then polish them with polishing paste. Use an X-ray diffractometer to perform phase analysis on the as-cast Al-Ce-Fe alloy without deep corrosion treatment, and the results are as Figure 3 shown.

[0071] The polished samples of as-cast alloy were immersed in a NaOH solution (mass percentage: 10% NaOH, 90% distilled water), stirred for 4 min, and rinsed with deionized water to complete the deep etching of the microstructure. Finally, a scanning electron microscope was used to observe the microstructure before and after the deep etching treatment. The results are as Figures 4 - 5 shown. Figure 4 The EDS analysis results of each point in

[0072] are shown in Table 3. Figure 4 EDS analysis results of each point (At.%)

[0073]

[0074] From Figure 3 the XRD analysis results, it can be seen that the as-cast Al-5Ce alloy mainly consists of cubic α-Al and orthorhombic Al 11 Ce3. After adding Fe, Al 13 Fe4 and Al 10 Fe2Ce phases are formed in the alloy, which is consistent with the Al-Ce-Fe ternary phase Figure 1 diagram.

[0075] As Figure 4 shown, the black part is the α-Al matrix. When the Fe content is the same, the α-Al size is smaller when the Ce content is higher, which is consistent with the decrease in the α-Al nucleation temperature in the cooling curve.

[0076] Among them, Figure 4 (c), (d), (e), (i), and (j) in 11 show the Al-xCe-1Fe alloy. The bright white part is the Al 10 Ce3 phase or Al 10 Fe2Ce phase. Through EDS analysis, it can be known that the ternary intermetallic compound Al Figure 4 (point B in (d)) and granular ( Figure 4 (point C in (e) and point I in (j))). Since during the solidification process of the Al-xCe-1Fe alloy, the Al-Fe eutectic transformation precedes the peritectic eutectic transformation and the Al-Ce-Fe ternary eutectic transformation, the Al 13 Fe4 phase is the first secondary phase to precipitate. However, through SEM and EDS analysis, no Fe-containing binary phase was found in the Al-xCe-1Fe alloy, indicating that during the peritectic eutectic reaction, the crystallized Al 13 Fe4 phase and the liquid phase underwent a peritectic eutectic transformation to form Al 10 Fe2Ce. Since the Fe content is relatively low, less Al 13 Fe4 is formed. Therefore, Al 13All Fe4 phase is converted to Al 10 Fe2Ce

[0077] As Figure 4 shown in (f), (g), (h), (k), (l), (m) for Al-xCe-2Fe alloys, with the increase of Fe content, the Al 13 Fe4 phase significantly increases, and the Al 13 Fe4 phase presents different morphologies. A small amount of massive Al 13 Fe4 phase appears in the Al-xCe-2Fe alloy ( Figure 4 point E in (g), point L in (m)), and the massive Al 13 Fe4 phase is the primary crystal Al 13 Fe4 phase directly crystallized from the liquid phase at the initial stage of alloy solidification. The primary Al 13 Fe4 phase in Al-3Ce-2Fe is relatively large in size, with a maximum length of up to 20 μm and uneven distribution, while the primary Al 13 Fe4 phase in Al-4Ce-2Fe is relatively small in size, with a maximum size of 12 μm and relatively uniform distribution.

[0078] Another type of Al 13 Fe4 phase presents as needle-like or short rod-like shapes ( Figure 4 the gray parts in (h) and (l)), which is the typical eutectic Al 13 Fe4 structure formed through the L→Al+Al 13 Fe4 eutectic transformation. There are Al 13 Fe4 phases surrounded by white tissues in the figure ( Figure 4 point E in (g), point G in (h) and point L in (m)). Through EDS analysis and combined with XRD analysis, it is found that the white tissue is Al 10 Fe2Ce ( Figure 4 points D, H, K in the figure). The reason is that during the peritectic eutectic transformation process, the liquid phase reacts with the Al 13 Fe4 phase to form the Al 10 Fe2Ce phase. However, since the Al 10 Fe2Ce phase adheres to the surface of the Al 13 Fe4 phase and quickly surrounds the Al 13 Fe4 phase, separating the Al 13 Fe4 phase from the liquid phase. To continue the peritectic eutectic transformation, atomic diffusion must occur through the Al 10 Fe2Ce phase layer, and then the liquid phase can interact with the Al 13 Fe4 phase to continue forming Al 10The Fe2Ce phase. The diffusion of atoms in the solid phase is much more difficult than that in the liquid phase, so the peritectic reaction rate is very slow. When the remaining liquid phase cools below the peritectic temperature, the untransformed Al 13 Fe4 phase remains in the Al 10 Fe2Ce phase. The edges and corners of this coated structure are relatively rounded, which not only reduces the splitting effect of the massive primary Al 13 Fe4 phase on the matrix, but also improves the heat resistance of the alloy. It can be found that the peritectic transformation is more likely to occur around the massive Al 13 Fe4 phase, which also indicates that at the initial stage of alloy solidification, the adsorption of Ce atoms affects the growth directionality of the primary Al 13 Fe4 phase. The primary Al 13 Fe4 phase does not grow into long needle-like shapes along its

[001] direction, but into massive shapes. The Ce atoms adsorbed on its surface promote the subsequent peritectic transformation.

[0079] As shown in Figure 4 (n) and (o) of Al-3Ce-3Fe alloy, since the Fe content exceeds the Al-Fe eutectic content, the amount of primary Al 13 Fe4 phase in the structure increases. The alloy not only has massive primary Al 13 Fe4 phase, but also a large number of long needle-like primary Al 13 Fe4 phases, with a maximum length of up to 80 μm and uneven distribution. The presence of this long needle-like brittle Al 13 Fe4 phase will greatly reduce the room-temperature mechanical properties of the material.

[0080] Figure 5 This is a backscattered electron image of the as-cast alloy after deep etching. The three-dimensional morphology of the structure was observed by deep etching the polished cross-section of the Al-Ce and Al-Ce-Fe alloys. In the Al-5Ce alloy, as shown in Figure 5 (a), the eutectic Al 11 Ce3 lamellae are relatively thick and interconnected, forming a skeletal morphology, which is consistent with the Figure 4 (a) morphology. As shown in Figure 5 (b), the coarse feathery Al 10 Fe2Ce phase in Al-4Ce-1Fe coexists with the lamellar eutectic Al 11 Ce3; as shown in Figure 5 (c), the Al 10 Fe2Ce phase and the eutectic Al 11 Ce3 in Al-3Ce-2Fe are smaller in size than those in Al-4Ce-1Fe; as shown in Figure 5 (d), Al-5Ce-1Fe mainly contains coarse and complex cross-section Al 11 Ce3 phase and a small amount of feathery Al10 The Fe2Ce phase; as Figure 5 shown in (e) below, the feathery Al in Al-4Ce-2Fe 10 Fe2Ce phase and the lamellar eutectic Al 11 Ce3 is similar to the microstructure of the Al-3Ce-2Fe alloy. Al-4Ce-2Fe, Al-3Ce-2Fe, and Al-4Ce-1Fe have finer and smaller lamellar spacing of Al 11 Ce3 phase compared to Al-5Ce and Al-5Ce-1Fe; among them, as the Ce content decreases, the interphase spacing of the eutectic Al 11 Ce3 phase decreases from 1.21 μm to 0.48 μm; the interphase spacing of the Al 11 Ce3 phase in the Al-4Ce-2Fe alloy is 0.4814 μm; the interphase spacing of the Al 11 Ce3 phase in the Al-3Ce-2Fe alloy is 0.4816 μm; the Al 10 Fe2Ce phase in Al-xCe-2Fe is finer than that in Al-xCe-1Fe, and the feathery Al 10 Fe2Ce phase changes from an average diameter of 1.6 μm to fine filaments and has a larger number.

[0081] ③ The as-cast Al-Ce-Fe alloys obtained in Example 1 were subjected to thermal exposure treatment at 200 °C and 300 °C for 120 hours respectively, and then cut into samples with Φ8×12 mm using a wire electrical discharge machine. The microstructure was observed using a scanning electron microscope, and the results are as Figure 6 shown. And X-ray diffractometer was used for phase analysis, and the results are as Figure 7 shown. Figure 6 The analysis results of EDS at each point in

[0082] Table 4 Figure 6 Analysis results of EDS at each point (At.%)

[0083]

[0084] Figure 6 are the microstructural photographs of the alloy after thermal exposure at 200 °C and 300 °C for 120 hours. Observed at low magnification, the overall as-cast microstructure is retained. Among them, the morphology of the eutectic Al 11 Ce3 phase does not change significantly, and the eutectic Al 13 Fe4 phase changes from needle-like and flaky to short rod-like and granular. There is no obvious change in the microstructure of Al-4Ce-1Fe and Al-5Ce-1Fe after thermal exposure at 200 °C, and there are still feathery ( Figure 6 point A in 10 ) and granular Al Figure 6Points B and D in the figure). After thermal exposure at 300 °C, the number of granular Al 10 Fe2Ce in the Al-4Ce-1Fe and Al-5Ce-1Fe microstructures increases. The coating phase microstructure formed by Al-3Ce-2Fe during the peritectic eutectic transformation ( Figure 5 Points E and G in the figure) still exists after thermal exposure at 200 °C, as shown by the phase circled in red in Figure 6 (h). After thermal exposure at 300 °C, the granular Al 10 Fe2Ce is slightly spheroidized ( Figure 6 Point C in the figure). The microstructure change of Al-4Ce-2Fe after thermal exposure is similar to that of Al-3Ce-2Fe. The comprehensive results show that in the Al-xCe-1Fe and Al-xCe-2Fe alloys in this experiment, the Al 10 Fe2Ce will not decompose into Al 13 Fe4 and Al 11 Ce3 phases within a relatively long time at high temperature, which indicates the stability of the alloy microstructure. That is, the ternary phase Al 10 Fe2Ce in the Al-Ce-Fe alloy has no adverse effect on the alloy.

[0085] ④ Use a Vickers hardness tester to test the hardness of the as-cast Al-Ce-Fe alloy specimens obtained in Example 1 and the alloy specimens after thermal exposure (200 °C, 300 °C). The results are as shown in Figure 8 .

[0086] As can be seen from Figure 8 , adding 1% Fe increases the hardness value of the as-cast Al-5Ce alloy by 19.7%, and the hardness reduction after thermal exposure at 300 °C is reduced by 8.7%. For the Al-4Ce-1Fe alloy with 1% Fe replacing 1% Ce, its hardness is increased by 24.3% compared to the Al-5Ce alloy hardness value. This is because when 1% Fe is added, the Al 10 Fe2Ce phase enhances the alloy hardness, and at the same time, the eutectic phase spacing of the eutectic Al 11 Ce3 microstructure is finer. For the Al-3Ce-2Fe alloy with 2% Fe replacing 2% Ce, its as-cast alloy hardness is similar to that of Al-4Ce-1Fe, and the hardness reduction of the alloy after thermal exposure at 200 °C and 300 °C is also small. Although the Ce content of Al-3Ce-2Fe decreases, more short rod-shaped and needle-shaped Al 13 Fe4 phases are formed, and the formed Al 10 Fe2Ce phase is finer and more evenly distributed. The hardness value of the as-cast Al-4Ce-2Fe alloy is slightly higher than that of Al-4Ce-1Fe, and the hardness reduction of the alloy after thermal exposure at 300 °C is significantly reduced. This is because when the Ce content is the same, when the Fe content is higher, fine and evenly distributed Al 13 Fe4 phases are formed, Al13 The Fe4 phase has good high-temperature stability. Therefore, in the Al-xCe-1Fe alloy, the formed Al 10 Fe2Ce enhances the hardness of the alloy. In the Al-xCe-2Fe alloy, in addition to the formation of finer Al 10 Fe2Ce phase, an eutectic Al 13 Fe4 is also formed, which enhances the hardness of the alloy. When the Fe content reaches 3%, a large number of long acicular primary Al 13 Fe4 phases are formed in the Al-3Ce-3Fe alloy, increasing the tendency of crack formation and greatly reducing the room-temperature mechanical properties of the material.

[0087] ⑤ The as-cast Al-Ce-Fe alloy obtained in Example 1 and the Al-Ce-Fe alloy after 120 hours of thermal exposure at 200 °C and 300 °C were cut into samples with a size of Φ8×12 mm using an electric spark cutting machine, and a hot compression experiment was carried out using a Gleeble3500-gtc thermodynamics simulation testing machine. The compression temperatures were room temperature, 200 °C and 300 °C (corresponding to the thermal exposure temperatures of each specimen), the strain rate was 0.1 s -1 , the heating rate was 5 °C / s, the holding time was 3 min, the cooling method was water cooling, and the compression amount was 50%. The maximum values of the flow stress of the alloy at each temperature (i.e., the compressive strength / MPa) are shown in Table 5.

[0088] Table 5 Maximum values of the flow stress of the alloy at each temperature (compressive strength) / MPa

[0089]

[0090] As can be seen from Table 5, with the increase in the replacement amount of Ce by Fe in the alloy, the compressive strength of the alloy increases. This is because with the increase in the Fe content, the eutectic Al 13 Fe4 phase increases. In the as-cast alloy, the Al 13 Fe4 phase mostly shows a short rod or needle-like shape and is distributed in the grains, and hardly changes after thermal exposure, which is beneficial to the high-temperature strength of the alloy. Through the deep etching of the as-cast alloy, it is found that the Al 11 Ce3 phase in Al-4Ce-2Fe is finer, the eutectic phase spacing is smaller, and the feather-like Al 10 Fe2Ce phase is also finer. All of the above play a role in hindering the dislocation movement during plastic deformation, increasing the strength of the alloy. Therefore, the strength of Al-4Ce-2Fe is the best. In this experiment, high-temperature compression experiments were carried out on the Al-6Ce alloy at various temperatures. The experimental results show that the compressive strength of Al-4Ce-2Fe at each temperature is higher than that of Al-6Ce, indicating that replacing Ce with Fe in the Al-Ce alloy can ensure excellent high-temperature resistance while reducing costs.

[0091] In summary, in the present invention, Ce in the Al-Ce alloy is replaced by Fe, and at the same time, the preparation process conditions are further optimized, achieving the purpose of improving the morphology of the eutectic Al 11 Ce3 phase, and generating Al 13 Fe4 phase and Al 10 Fe2Ce phase, which improves the room temperature strength of the alloy and also improves the heat resistance performance.

[0092] Obviously, the above embodiments are only examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the claims of this patent application.

Claims

1. An Al-containing 10 Al-Ce-Fe alloy with an Fe2Ce phase, characterized in that The mass fraction of Ce in the Al-Ce-Fe alloy is 3-5%, the mass fraction of Fe is 2%, and the balance is Al and inevitable impurity elements; the Al-Ce-Fe alloy has feathery and / or granular Al 10 Fe2Ce phase, and skeletal eutectic Al 11 Ce3 phase; it also has massive and long needle-like primary crystal Al 13 Fe4 phase, and short rod-like and / or needle-like flake eutectic Al 13 Fe4 phase.

2. The Al-Ce-Fe alloy according to claim 1, characterized in that, Al in the Al-Ce-Fe alloy 10 The Fe2Ce phase coats the massive and long acicular primary Al 13 outside the Fe4 phase; the primary Al 13 The size of the Fe4 phase is ≤20 μm; the phase spacing of the eutectic Al 11 Ce3 phase is 0.4 - 0.5 μm.

3. A kind of Al-containing 10 Preparation method of Al-Ce-Fe alloy with Fe2Ce phase, characterized in that, It includes the following steps: (1) Batching: Weigh industrial pure aluminum, Al-rich cerium mixed rare earth master alloy, and Al-Fe master alloy according to the mass ratio of each element in the Al-Ce-Fe alloy described in any one of claims 1 to 2, and set aside. The Al-rich cerium mixed rare earth master alloy is Al-10% rich cerium mixed rare earth master alloy, in which the mass percentage content of Ce is 7-8%, and the mass percentage content of La is 1-2%. The mass percentage content of Fe in the Al-Fe master alloy is 20%. (2) Melting: Heat industrial pure aluminum, Al-rich cerium mixed rare earth master alloy, and Al-Fe master alloy until completely melted to obtain an Al-Ce-Fe metal solution. The heating temperature is 740-790 °C, and after reaching the target temperature, hold for 30-50 min. (3) Refining: Add hexachloroethane to the Al-Ce-Fe metal solution, stir evenly, skim off the surface scum, then carry out heat preservation treatment, and carry out slag skimming treatment after heat preservation to prepare for pouring. The stirring time after adding hexachloroethane is 2-5 min. The temperature for heat preservation treatment is 750-800 °C, and the heat preservation time is 20-30 min. (4) Pouring: Pour the Al-Ce-Fe metal solution into the mold to obtain the product.

4. The preparation method according to claim 3, characterized in that, In the step (1), the mass percentage content of Al in industrial pure aluminum is ≥99%.

5. The preparation method according to claim 3, wherein In the step (2), the heating temperature is 750 °C, and after reaching the target temperature, hold for 40 min.

6. The preparation method according to claim 3, characterized in that, In the step (3), the mass of hexachloroethane added is 0.02%-0.05% of the mass of the Al-Ce-Fe metal solution.

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