Al-Ni-Cu-Ce series heat-resistant aluminum alloy and preparation method and application thereof

Abstract

The invention provides an Al-Ni-Cu-Ce series heat-resistant aluminum alloy as well as a preparation method and application thereof. The aluminum alloy comprises an aluminum matrix as well as an eutectic heat-resistant phase and gamma-Al2O3 particles which are distributed in the aluminum matrix, the eutectic heat-resistant phase is at least one of an Al3Ni intermetallic compound, an Al11Ce3 intermetallic compound, an Al3CeCu intermetallic compound, an Al8CeCu4 intermetallic compound and an Al7Cu4Ni intermetallic compound, and the eutectic heat-resistant phase is distributed in a three-dimensional framework shape; the gamma-Al2O3 is in a chain form and is distributed between the eutectic heat-resistant phases; the mass percent of Ce in the Al-Ni-Cu-Ce series heat-resistant aluminum alloy is 3.0 to 12.0 percent; the mass percent of Ni is 1.8 to 8.1 percent; the mass percent of Cu is 2.0 to 10.2 percent; the mass percent of the gamma-Al2O3 is 0.5 to 2.0 percent. The aluminum alloy has the advantages of being high in strength and good in stability under the high-temperature condition.

Description

Technical Field

[0001] The invention belongs to the field of aluminum alloys, and specifically relates to an Al-Ni-Cu-Ce series heat-resistant aluminum alloy and a preparation method and application thereof. Background Art

[0002] Aluminum alloys have the advantages of low density, high specific strength and corrosion resistance, and are now widely used in the fields of automobiles, aerospace, etc. With the rapid development of my country in the fields of transportation, national defense and military industry, higher requirements have been put forward for the heat resistance of aluminum alloys. The temperature of aluminum alloy parts used in key fields has been increased from the traditional 250℃ to more than 400℃. Therefore, it is urgent to develop new heat-resistant and high-strength aluminum alloys.

[0003] Traditional cast heat-resistant aluminum alloys include Al-Si-Cu and Al-Cu series, which are widely used in hot end parts such as cylinder blocks and cylinder heads of fuel engines. Since the main strengthening elements in the alloy are Mg, Cu, etc., fine metastable phases such as β', β” and θ' are formed after aging treatment, which improve the strength of the alloy by exerting dispersion strengthening. However, this type of precipitated phase will rapidly coarsen and transform into an equilibrium phase after exceeding a certain temperature, which seriously reduces the heat resistance of the alloy, resulting in a relatively limited working temperature of traditional cast heat-resistant aluminum alloys.

[0004] As we all know, grain refinement is an effective means of strengthening aluminum alloys at room temperature, but not at high temperatures. When the material is plastically deformed at room temperature, the grain boundary is a "strong point" compared to the interior of the grain. The movable dislocations generated during the stretching process are blocked by the grain boundary and piled up, causing the alloy to produce greater work hardening. However, at high temperatures (about the ratio temperature T / Tm>0.4~0.5, Tm refers to the melting point or solidus temperature of the alloy), the atoms at the grain boundary have increased thermal vibration amplitudes and decreased interatomic bonding forces, which greatly reduces their obstruction to dislocations and becomes a "weak point" compared to the interior of the grain. Therefore, in theory, the key to improving the heat resistance of aluminum alloys is to improve the high-temperature strength of the grain boundaries. In fact, the multi-component Al-Si-Cu-Mg-Ni alloy used to manufacture engine pistons can precipitate heat-resistant phases such as Al3CuNi during the solidification process. Although they are distributed at the grain boundaries, the overlap between the heat-resistant phases is limited and the connectivity is low, making the heat-resistant skeleton constructed by them imperfect, thereby limiting the further improvement of the high-temperature strength of the alloy.

[0005] Therefore, it is an effective way to develop new heat-resistant and high-strength aluminum alloys by using alloy composition and preparation process to build and regulate the second phase heat-resistant skeleton, which has important practical significance for meeting the urgent needs of civil and national defense fields. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides an Al-Ni-Cu-Ce series heat-resistant aluminum alloy and a preparation method and application thereof. The Al-Ni-Cu-Ce series heat-resistant aluminum alloy of the present invention has the characteristics of a highly connected skeleton structure constructed by chain-like γ-Al2O3 particles and multi-element eutectic heat-resistant phases, and has the advantages of high strength and good stability under high temperature conditions.

[0007] The present invention is achieved in the following ways:

[0008] An Al-Ni-Cu-Ce series heat-resistant aluminum alloy, comprising an aluminum matrix and a eutectic heat-resistant phase and γ-Al2O3 particles distributed in the aluminum matrix; the eutectic heat-resistant phase is Al3Ni, Al 11 At least one of Ce3, Al3CeCu, Al8CeCu4, and Al7Cu4Ni intermetallic compounds presents a three-dimensional skeleton distribution; the γ-Al2O3 is in chain form and distributed between eutectic heat-resistant phases; the mass percentage of Ce in the Al-Ni-Cu-Ce series heat-resistant aluminum alloy is 3.0-12.0%; the mass percentage of Ni is 1.8-8.1%; the mass percentage of Cu is 2.0-10.2%; and the mass percentage of γ-Al2O3 is 0.5-2.0%.

[0009] Preferably according to the present invention, the eutectic heat-resistant phase is generated by a multi-element eutectic reaction, and the size of the eutectic heat-resistant phase is 1 to 100 μm, which is a micron scale, and has a high melting point.

[0010] Preferably, according to the present invention, the size of the γ-Al2O3 particles is 0.1 to 2 μm, which is submicron level; the γ-Al2O3 particle chain plays the role of connecting the heat-resistant phases in series and jointly building a high-connectivity skeleton structure.

[0011] The preparation method of the Al-Ni-Cu-Ce series heat-resistant aluminum alloy comprises the following steps:

[0012] (1) First, the required raw materials are prepared according to the following mass percentages: 6-27% of Al-30Ni master alloy, 10-40% of Al-30Ce master alloy, 2-13% of Al-50Cu master alloy, 8-31% of Al-15CuO preform, and the rest is industrial pure aluminum;

[0013] (2) weighing the materials in step (1) in proportion, first melting industrial pure aluminum to obtain an aluminum melt;

[0014] (3) placing Al-30Ni, Al-30Ce and Al-50Cu master alloys into the aluminum melt prepared in step (2) and melting them to obtain alloy melt A;

[0015] (4) placing the Al-15CuO preform into the alloy melt A prepared in step (3) and melting the melt to obtain alloy melt B;

[0016] (5) Casting the alloy melt B in step (4) into a preheated cast iron mold to obtain an Al-Ni-Cu-Ce alloy.

[0017] Preferably according to the present invention, the melting temperature in step (2) is 750-800° C. and the holding time is 1-3 h.

[0018] Preferably according to the present invention, the melting temperature in step (3) is 820-880° C., and the holding time is 2-5 h.

[0019] Preferably, according to the present invention, the melting temperature in step (4) is 720-760° C., and the holding time is 15-30 min.

[0020] Preferably according to the present invention, the preheating temperature of the cast iron mold in step (5) is 100-300°C; and the casting temperature is 720-760°C.

[0021] According to the present invention, the above-mentioned Al-Ni-Cu-Ce heat-resistant aluminum alloy is used to prepare components for high-temperature working environments, wherein the maximum temperature of the high-temperature working environment is not less than 300°C; the components for the high-temperature working environment are such as the cylinder block and cylinder head of a fuel engine.

[0022] In the present invention, Al-30Ni master alloy means that the mass fraction of Ni in the Al-30Ni master alloy is 30%, Al-30Ce master alloy means that the mass fraction of Ce in the Al-30Ce master alloy is 30%, Al-50Cu master alloy means that the mass fraction of Cu in the Al-50Cu master alloy is 50%, and Al-15CuO preform means that the mass fraction of CuO in the Al-15CuO preform is 15%.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The present invention uses Ni, Cu, Ce in a specific ratio to react with Al to form Al3Ni, Al 11 At least one of various heat-resistant phases such as Ce3, Al3CeCu, Al8CeCu4, Al7Cu4Ni, etc. This type of eutectic heat-resistant phase has excellent thermal stability below 450°C and a high volume fraction. It is distributed in the aluminum matrix in a skeleton-like morphology, which greatly improves the heat resistance of the aluminum alloy.

[0025] 2. The present invention adds an Al-15CuO preform to the aluminum alloy, in which the in-situ generated γ-Al2O3 particles are well bonded to the interface of the aluminum matrix, forming a chain-like morphology and distributed in each eutectic heat-resistant phase, thereby connecting different parts of the eutectic heat-resistant phase in series and jointly constructing a highly connected three-dimensional skeleton structure to better strengthen the grain boundaries at high temperatures.

[0026] 3. The present invention reasonably matches the types and proportions of alloying elements, and prepares a heat-resistant aluminum alloy through the synergistic effect of the eutectic heat-resistant phase and γ-Al2O3 particles; the Al-Ni-Cu-Ce heat-resistant aluminum alloy of the present invention has the characteristics of simple process, good casting performance, and no need for heat treatment, which greatly saves costs and can be prepared on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the microstructure of the aluminum alloy of the present invention, wherein 1 is the aluminum matrix, 2 is the eutectic heat-resistant phase, and 3 is the γ-Al2O3 particle chain.

[0028] Figure 2 This is the XRD spectrum of the Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared in Example 1.

[0029] Figure 3 The microstructure of the Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared in Example 1; 1 is the aluminum matrix, 2 is the Al 11 The eutectic cluster is composed of Ce3, Al3Ni and Al3CeCu heat-resistant phases, and 3 is a γ-Al2O3 particle chain.

[0030] Figure 4 The microstructure of the Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared in Comparative Example 1 is shown in FIG. 1 , the aluminum matrix is ​​shown in FIG. 2 , the eutectic composed of Al3Ni and Al3CeCu heat-resistant phases is shown in FIG. 3 , and the Al3Ni-Cu-Ce heat-resistant phase is shown in FIG. 11 Ce3,4 is primary blocky Al3Ni. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below through specific embodiments, but the content of the present invention is not limited to the following embodiments.

[0032] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are all commercially available unless otherwise specified.

[0033] Example 1

[0034] A method for preparing an Al-Ni-Cu-Ce series heat-resistant aluminum alloy comprises the following steps:

[0035] (1) First, the required raw materials are prepared according to the following mass percentages: 8% of Al-30Ni master alloy, 30% of Al-30Ce master alloy, 5% of Al-50Cu master alloy, 10% of Al-15CuO preform, and the rest is industrial pure aluminum;

[0036] (2) Weighing the materials in step (1) in proportion, firstly putting industrial pure aluminum into a clay crucible to melt to obtain aluminum melt; the melting temperature is 750° C., and the holding time is 2 h;

[0037] (3) placing Al-30Ni, Al-30Ce and Al-50Cu master alloys into the aluminum melt in step (2) and melting them to obtain alloy melt A; the melting temperature is 850° C. and the holding time is 4 h;

[0038] (4) placing the Al-15CuO preform into the alloy melt A in step (3) to melt and obtain alloy melt B; the melting temperature is 730° C. and the holding time is 15 min.

[0039] (5) Casting the alloy melt B in step (4) into a preheated cast iron mold to obtain an Al-Ni-Cu-Ce series heat-resistant aluminum alloy; the preheating temperature of the cast iron mold is 300°C, and the casting temperature is 730°C.

[0040] The Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared according to the above ratio and process has a composition (mass percentage) of Al-2.4Ni-3.7Cu-9.0Ce-0.6Al2O3, and the aluminum matrix contains Al3Ni, Al 11 Ce3 and Al3CeCu heat-resistant phases, γ-Al2O3 is distributed in the eutectic heat-resistant phase in a chain shape. The ultimate tensile strength of the obtained alloy at room temperature and 350℃ is 366MPa and 238MPa respectively. Figure 2 This is the XRD picture of the Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared in this embodiment. In addition to the Al matrix phase, Al3Ni, Al 11 Ce3, Al3CeCu and γ-Al2O3 phases. Figure 3 The microstructure of the Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared in this embodiment, 1 is the aluminum matrix, 2 is the Al 11 The eutectic cluster is composed of Ce3, Al3Ni and Al3CeCu heat-resistant phases, and 3 is a γ-Al2O3 particle chain.

[0041] Example 2

[0042] A method for preparing an Al-Ni-Cu-Ce series heat-resistant aluminum alloy comprises the following steps:

[0043] (1) First, the required raw materials are prepared according to the following mass percentages: 15% of Al-30Ni master alloy, 25% of Al-30Ce master alloy, 7% of Al-50Cu master alloy, 16% of Al-15CuO preform, and the rest is industrial pure aluminum;

[0044] (2) Weigh the materials in step (1) in proportion, first put industrial pure aluminum into a clay crucible and melt it to obtain aluminum melt; the melting temperature is 765° C. and the holding time is 2 h;

[0045] (3) placing Al-30Ni, Al-30Ce and Al-50Cu master alloys into the aluminum melt in step (2) and melting them to obtain alloy melt A; the melting temperature is 820° C. and the holding time is 5 h;

[0046] (4) placing the Al-15CuO preform into the alloy melt A in step (3) to melt and obtain alloy melt B; the melting temperature is 725° C. and the holding time is 20 min.

[0047] (5) Casting the alloy melt B in step (4) into a preheated cast iron mold to obtain an Al-Ni-Cu-Ce series heat-resistant aluminum alloy; the preheating temperature of the cast iron mold is 200°C, and the casting temperature is 725°C.

[0048] The Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared according to the above ratio and process has a composition (mass percentage) of Al-4.5Ni-5.4Cu-7.5Ce-1.0Al2O3, and the aluminum matrix contains Al3Ni, Al 11 Ce3, Al3CeCu and Al8CeCu4 heat-resistant phases, γ-Al2O3 is distributed in the eutectic heat-resistant phase in a chain shape. The ultimate tensile strength of the obtained alloy at room temperature and 350℃ is 382MPa and 251MPa respectively.

[0049] Example 3

[0050] A method for preparing an Al-Ni-Cu-Ce series heat-resistant aluminum alloy comprises the following steps:

[0051] (1) First, the required raw materials are prepared according to the following mass percentages: 20% Al-30Ni master alloy, 35% Al-30Ce master alloy, 10% Al-50Cu master alloy, 30% Al-15CuO preform, and the rest is industrial pure aluminum;

[0052] (2) Weighing the materials in step (1) in proportion, firstly putting industrial pure aluminum into a clay crucible to melt to obtain aluminum melt; the melting temperature is 780° C., and the holding time is 1.5 h;

[0053] (3) placing Al-30Ni, Al-30Ce and Al-50Cu master alloys into the aluminum melt in step (2) to melt and obtain alloy melt A; the melting temperature is 860° C. and the holding time is 3 h;

[0054] (4) placing the Al-15CuO preform into the alloy melt A in step (3) to melt and obtain alloy melt B; the melting temperature is 750° C. and the holding time is 15 min.

[0055] (5) Casting the alloy melt B in step (4) into a preheated cast iron mold to obtain an Al-Ni-Cu-Ce series heat-resistant aluminum alloy; the preheating temperature of the cast iron mold is 300°C, and the casting temperature is 750°C.

[0056] The Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared according to the above ratio and process has a composition (mass percentage) of Al-6.0Ni-8.6Cu-10.5Ce-1.9Al2O3, and the aluminum matrix contains Al3Ni, Al7Cu4Ni, Al3CeCu and Al8CeCu4 heat-resistant phases, and γ-Al2O3 is distributed in the eutectic heat-resistant phase in a chain shape. The ultimate tensile strength of the obtained alloy at room temperature and 350°C is 396MPa and 267MPa, respectively.

[0057] Comparative Example 1

[0058] A method for preparing an Al-Ni-Cu-Ce series heat-resistant aluminum alloy comprises the following steps:

[0059] (1) First, the required raw materials are prepared according to the following mass percentages: 15% of Al-30Ni master alloy, 31% of Al-30Ce master alloy, 8% of Al-50Cu master alloy, and the rest is industrial pure aluminum;

[0060] (2) Weighing the materials in step (1) in proportion, firstly putting industrial pure aluminum into a clay crucible to melt to obtain aluminum melt; the melting temperature is 800° C., and the holding time is 1.5 h;

[0061] (3) placing Al-30Ni, Al-30Ce and Al-50Cu master alloys into the aluminum melt in step (2) to melt and obtain alloy melt; the melting temperature is 860° C. and the holding time is 3 h;

[0062] (4) Casting the alloy melt in step (3) into a preheated cast iron mold to obtain an Al-Ni-Cu-Ce series heat-resistant aluminum alloy; the preheating temperature of the cast iron mold is 150°C, and the casting temperature is 750°C.

[0063] The Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared according to the above ratio and process has a composition (mass percentage) of Al-4.5Ni-4.0Cu-9.3Ce, and the aluminum matrix contains Al 11 Ce3, Al3Ni and Al3CeCu heat-resistant phases are interconnected in their respective regions, but due to the lack of the series effect of chain-like γ-Al2O3 particles, the skeleton strength constructed by the heat-resistant phases in the microstructure is limited. The ultimate tensile strength of the obtained alloy at room temperature and 350°C is 146MPa and 71MPa, respectively. Figure 4 The microstructure of the Al-Ni-Cu-Ce heat-resistant aluminum alloy prepared in this comparative example, in which 1 is the aluminum matrix, 2 is the eutectic composed of Al3Ni and Al3CeCu heat-resistant phases, 3 is Al 11 Ce3,4 is primary blocky Al3Ni.

Claims

1. An Al-Ni-Cu-Ce series heat-resistant aluminum alloy, characterized in that: The Al-Ni-Cu-Ce series heat-resistant aluminum alloy comprises an aluminum matrix and a eutectic heat-resistant phase and γ-Al2O3 particles distributed in the aluminum matrix; the eutectic heat-resistant phase is Al3Ni, Al 11 At least one of Ce3, Al3CeCu, Al8CeCu4, and Al7Cu4Ni intermetallic compounds presents a three-dimensional skeleton distribution; the γ-Al2O3 is in chain form and distributed between eutectic heat-resistant phases; the mass percentage of Ce in the Al-Ni-Cu-Ce series heat-resistant aluminum alloy is 3.0-12.0%; the mass percentage of Ni is 1.8-8.1%; the mass percentage of Cu is 2.0-10.2%; and the mass percentage of γ-Al2O3 is 0.5-2.0%.

2. The Al-Ni-Cu-Ce heat-resistant aluminum alloy according to claim 1, characterized in that: The size of the eutectic heat-resistant phase is 1 to 100 μm.

3. The Al-Ni-Cu-Ce heat-resistant aluminum alloy according to claim 1, characterized in that: The size of the γ-Al2O3 particles is 0.1 to 2 μm.

4. The method for preparing the Al-Ni-Cu-Ce heat-resistant aluminum alloy according to claim 1, comprising the following steps: (1) First, the required raw materials are prepared according to the following mass percentages: 6-27% of Al-30Ni master alloy, 10-40% of Al-30Ce master alloy, 2-13% of Al-50Cu master alloy, 8-31% of Al-15CuO preform, and the rest is industrial pure aluminum; (2) Weighing the materials in step (1) in proportion, first melting industrial pure aluminum to obtain an aluminum melt; (3) placing Al-30Ni, Al-30Ce and Al-50Cu master alloys into the aluminum melt prepared in step (2) and melting them to obtain alloy melt A; (4) placing the Al-15CuO preform into the alloy melt A prepared in step (3) and melting the melt to obtain alloy melt B; (5) Casting the alloy melt B in step (4) into a preheated cast iron mold to obtain an Al-Ni-Cu-Ce alloy.

5. The method for preparing the Al-Ni-Cu-Ce series heat-resistant aluminum alloy according to claim 4, characterized in that: The melting temperature in step (2) is 750-800° C., and the holding time is 1-3 hours.

6. The method for preparing the Al-Ni-Cu-Ce series heat-resistant aluminum alloy according to claim 4, characterized in that: The melting temperature in step (3) is 820-880° C., and the insulation time is 2-5 hours.

7. The method for preparing the Al-Ni-Cu-Ce series heat-resistant aluminum alloy according to claim 4, characterized in that: The melting temperature in step (4) is 720-760° C., and the holding time is 15-30 minutes.

8. The method for preparing the Al-Ni-Cu-Ce series heat-resistant aluminum alloy according to claim 4, characterized in that: In step (5), the preheating temperature of the cast iron mold is 100-300°C; the casting temperature is 720-760°C.

9. Application of the Al-Ni-Cu-Ce heat-resistant aluminum alloy according to claim 1 for preparing components for high-temperature working environments, wherein the maximum temperature of the high-temperature working environment is not less than 300°C.

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