CN111321326A - Al-RE-Y-Mg alloy and preparation method thereof - Google Patents

Abstract

The invention provides an Al-RE-Y-Mg alloy and a preparation method thereof, wherein the alloy comprises the following chemical components in percentage by mass: 4-10% of RE, 0.3-4% of Y, 0.2-0.4% of Mg, and the balance of Al and other inevitable impurities. Wherein RE is at least one element of La and Ce. After the Al-RE-Y-Mg alloy is subjected to pressure casting, the room-temperature tensile strength of the die-cast alloy reaches 260MPa, and the elongation is 11%; the tensile strength of the high-temperature tensile reaches 130MPa at 250 ℃, and the elongation is 19 percent; after gravity casting, the tensile strength at room temperature reaches 145MPa, and the elongation is 14%; the heat conductivity coefficient is 178W/(m.K), the alloy can be used without subsequent heat treatment, and the high-end requirement of the industries of aerospace, war industry, automobiles and the like on light weight development is met.

Description

Al-RE-Y-Mg alloy and preparation method thereof

technical field

The invention belongs to the field of industrial aluminum alloy and its manufacture, and relates to an Al-RE-Y-Mg alloy and a preparation method thereof; in particular, it relates to a high-strength, toughness, heat-resisting die-casting/high thermal conductivity and corrosion-resistant alloy suitable for pressure/gravity casting Al-RE-Y-Mg alloy.

Background technique

Aluminum alloy is a general term for alloys with aluminum as the matrix. It has the characteristics of low density, high strength, and excellent specific strength. The main alloy systems are Al-Si system, Al-Cu system, Al-Mg system and so on. It has a wide range of applications in the fields of transportation, automobiles, machinery manufacturing, and aerospace. In particular, the heat-resistant aluminum alloy used as a wire needs to have good heat resistance under the condition of ensuring good electrical conductivity and oxidation resistance, which is conducive to improving the current carrying capacity and reducing the loss. Heat-resistant aluminum alloys used in mechanical equipment are required to maintain good mechanical properties and creep fatigue resistance at relatively high temperatures. Applications in the automotive industry often bear continuous loads and vibrations during service, which requires higher creep fatigue properties of parts, so the demand for aluminum alloys with special use requirements is getting higher and higher.

Rare earth has always been an element used for refinement and strengthening in aluminum alloys. A high-strength Al-Zn-Mg aluminum alloy disclosed in Chinese invention patent 201910683881.4 (a high-strength aluminum alloy) is composed of the following percentages: 5.3-5.7%Zn, 2.2-2.6%Mg, 1.3-1.8%Cu, 0.2-0.5%Si, 0.3-0.6%Fe, 0.2-0.4%Mn, 0.06-0.2%Cr, 0.06-0.15%Ce/La, 0.2-0.8% Ag, the balance is Al. The addition of 0.06-0.15wt% of La/Ce rare earth can significantly promote the formation of rare earth strengthening phase and dispersion strengthening phase, and improve the dispersion and precipitation characteristics of precipitation in the aluminum alloy, thereby significantly improving the compressive strength and yield strength of the aluminum alloy. However, the addition of La/Ce rare earth is generally only added as a microalloying element, not as a main element, and its addition amount is generally less than 1 wt%. A rare earth aluminum alloy intermediate material disclosed in Chinese invention patent ZL201610127881.2 (a high-strength, high-toughness rare earth aluminum alloy material and its preparation method) is composed of the following percentage components: 2.0%-2.5% Ce, 2.0%-2.6% La, Sc≤1.5%, and the balance is Al. Using the mixture of Sc and La/Ce rare earth, Sc mainly acts on the Al matrix, and forms Al3Sc nano-precipitated phase after heat treatment, thereby improving the strength. At present, there are still the following problems, in which adding no more than 1.5wt% of Sc as a method to increase its strength and maintain elongation, because the Sc element is expensive, it is not suitable for industrial production and mass use; on the other hand, this rare earth aluminum The alloy is added as an intermediate alloy and is not used as an alloy.

In the lightweight of automobiles, aluminum-silicon alloys are the most used, which have been widely used in the production of engine cylinder blocks, cylinder heads and wheel hubs. The representative alloys are A354, A356 and A380. Compared with ordinary gravity casting, die casting has faster punching speed, high productivity, easy mechanization and automation, and complex thin-walled parts. Secondly, the dimensional accuracy of die castings is high, the surface roughness is small, and subsequent machining is less or does not require machining. In the automotive industry, more than 90% of key structural parts are made of A380 alloy suitable for die casting. This is due to its good fluidity and superior toughness. However, the mechanical properties and creep fatigue properties of Al-Si alloys at 200 °C and above decrease rapidly, which cannot meet the normal use. In the Al-RE system alloy with La/Ce as the main element, the main phase is Al11RE3 phase, its high temperature stability is much higher than that of Si phase, and it also has excellent fluidity. Chinese invention patent 201910650876.3 (a near-eutectic high-strength heat-resistant Al-Ce aluminum alloy and its preparation method) discloses a near-eutectic high-strength heat-resistant Al-Ce aluminum alloy composition: Ce 5.00% to 15.00%, Fe 0.01% to 5.00%, Mg 0.10% to 1.20%, Si 0.05% to 1.00%, and Cu 0.001% to 5.00%. Its tensile strength reaches over 440 MPa; at 300° C., the tensile strength of the aluminum alloy reaches over 250 MPa. At present, the following problems still exist: the process used is continuous casting and rolling or rapid solidification. This process has high production cost, long production cycle, and cannot produce large and complex parts.

The high-temperature Ce-modified aluminum alloy mentioned in the international invention patent WO 2017/007908A1 (a high-temperature Ce-modified aluminum alloy that can be cast) discloses an aluminum alloy containing an X element composed of Ce or La, and the X content is 5- 30wt%, forming Al11X3 precipitation phase, the disclosed composition includes Al-8Ce, Al-10Ce, Al-12Ce, its yield strength is between (6.2-8.5ksi or 43-59MPa), elongation> 8%, Al-6Ce Yield strength 28-40MPa, Al-16Ce yield strength 68-70MPa, elongation only 2.0-2.5%, Al-12Ce-0.4Mg yield strength 76-79MPa, elongation only 2.5-6.0%, Al-12Ce-0.25 The yield strength of Zr is 45MPa, and the yield strength of Al-12Ce-1.3Ti is 43-47MPa. These results are consistent with the results of their published papers (Z.C.Sims, D.Weiss, S.K.McCall, et al., Cerium-Based, Intermetallic-Strengthened Aluminum Casting Alloy: High-Volume Co-product Development, JOM 68 (7) (2016) 1940-1947.) At present, the following problems still exist: The Al11RE3 phase produced by the RE and Al produced by the mixing of Ce and La is lath-like, and the size It is relatively coarse, resulting in very low mechanical properties of Al-RE alloy, and the yield strength does not exceed 90MPa. The Al11RE3 phase produced by RE and Al is prone to segregation, resulting in severe segregation, forming a coarse primary phase, which seriously affects its properties, especially the elongation, among which the elongation of Al-16Ce is only 2-2.5%. Adding 0.4wt% Mg increases the yield strength by about 20MPa, but the elongation decreases from 8.5% to 6.0%, and if excessive Mg is added, the solidification interval increases rapidly and the melt is oxidized, which seriously reduces the castability. Simultaneous addition of conventional refiners Zr and Ti has little improvement in yield strength. The high-strength and toughness non-heat-treatment reinforced die-casting aluminum alloy mentioned in Chinese invention patent 201910434413.3 (a high-strength and toughness non-heat-treatment reinforced die-casting aluminum alloy and its preparation method) discloses an aluminum alloy whose composition content RE: 7-10wt%, Mg : 0.05 to 0.5%, Ti: 0.05 to 0.1%. The as-cast yield strength is greater than 150MPa, the tensile strength is greater than 200MPa, and the elongation is greater than 10%. At present, the following problems still exist: the Al11RE3 phase produced by RE and Al is prone to segregation, resulting in serious segregation, forming a coarse primary phase, and seriously affecting its performance. The improvement of yield strength by adding a small amount of Mg is between solid solution strengthening and precipitation strengthening, that is, between 5-20 MPa. Classic books on light alloys give the contribution of Mg solid solution strengthening to yield strength of about 5-15 MPa (I.J. Polmear, Light Alloys: From Traditional Alloys to Nanocrystals, 4th edition, Butterworth-Heinemann, 2006, 421. p. 32). In contrast to the given example 2 (composition Al-4Ce-4La-0.25Mg-0.1Ti, yield strength 165MPa) and example 5 (composition Al-4Ce-4La-0.5Mg-0.1Ti, yield strength 170MPa), adding Mg The increase in yield strength is only 5MPa. The addition of Ti alone is not easy to form Al3Ti as a heterogeneous core, and the improvement of yield performance through refinement is not obvious. Comparing its given example 1 (composition Al-8Ce-0.25Mg-0.1Ti, yield strength 174 MPa) and example 5 (composition Al-5Ce-5La-0.1Mg-0.1Ti, yield strength 190 MPa), it can be seen that the addition of an additional 1 The contribution of %RE rare earth to yield strength is about 10 MPa (considering Example 1 performance includes the contribution of Mg to yield strength). Further comparing Example 2 (component Al-4Ce-4La-0.25Mg-0.1Ti, yield strength 165MPa) and Example 4 (component Al-7La-0.05Mg-0.1Ti, yield strength 150MPa), it is found that the addition of Ti element has an effect on yield strength. The lift is almost 0, considering its strength difference of 15 MPa mainly contributed by 10 MPa of 1% RE and 5 MPa contributed by 0.2% Mg. Therefore, the contribution of adding 0-0.5% Mg element to the yield strength is about 5-20 MPa, and the contribution of adding Ti to the strength is not obvious, less than 5 MPa.

Therefore, there is an urgent need to develop a high-strength, toughness and heat-resistant die-casting aluminum alloy; especially, a high-strength, toughness, and heat-resistant die-casting aluminum alloy suitable for pressure casting.

Chinese invention patent 201910720696.8 (a kind of high-strength aluminum alloy anodic oxidation electrolyte and high-strength aluminum alloy anodic oxide film preparation method and high-strength aluminum alloy workpiece) discloses a high-strength aluminum alloy anodic oxide film preparation method, using 0.1～0.2mol/L The method of anodic oxidation of phytic acid improves its corrosion resistance. At present, there are still the following problems: first, the anode coating needs to use corrosive liquid, which is not conducive to environmental protection; second, the resulting film is easy to be damaged, and its corrosion resistance is greatly reduced. Chinese invention patent 201910378236.1 (a method for preparing a medium-strength corrosion-resistant aluminum alloy sheet) discloses an Al-Mg-Mn-Cr corrosion-resistant aluminum alloy, the composition of which is that the content of Mg is 4.0%-5.0%, and the content of Mn is 0.3%-1.0%, Cr content is 0-0.3%, Zr content is 0-0.4%, Fe content is 0-0.35%. At present, there are still the following problems: Al-Mg alloy has poor casting performance and is prone to defects in the gravity casting process; secondly, this alloy requires multiple passes of subsequent hot rolling, which consumes huge amounts of energy, and cannot produce large and complex parts. Chinese invention patent ZL201910650876.3 (a near-eutectic high-strength heat-resistant Al-Ce aluminum alloy and its preparation method) discloses a near-eutectic high-strength heat-resistant Al-Ce aluminum alloy Composition: Ce 5.00%～15.00 %, Fe 0.01% to 5.00%, Mg 0.10% to 1.20%, Si 0.05% to 1.00%, Cu 0.001% to 5.00%. Its tensile strength reaches over 440 MPa; at 300° C., the tensile strength of the aluminum alloy reaches over 250 MPa. At present, the following problems still exist: the patent adopts a continuous casting and continuous rolling process, which has high production cost and long production cycle.

Therefore, there is an urgent need to develop a high thermal conductivity and corrosion-resistant aluminum alloy suitable for gravity casting.

SUMMARY OF THE INVENTION

In order to solve the problem that the existing cast rare-earth aluminum alloy cannot meet the industrial requirements (such as cast aluminum alloy such as A380) due to insufficient strength, toughness and heat resistance, and its application is greatly restricted, the present invention provides an Al-RE alloy. -Y-Mg alloy and its preparation method, after the alloy is pressure-cast, the alloy's room temperature tensile strength reaches 260MPa, and the elongation reaches 11%; the high-temperature tensile strength at 250°C reaches 130MPa, and the elongation reaches 19%; the After gravity casting of the alloy, the room temperature tensile strength reaches 145MPa, the elongation reaches 14%, and the thermal conductivity reaches 178W/(m·K).

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

The invention provides an Al-RE-Y-Mg alloy, which is composed of the following elements by mass percentage: 4-10% RE, 0.3-4% Y, 0.2-0.4% Mg, and the balance is Al element and non-ferrous metals. Avoid impurity elements.

Further, it is composed of the following elements by mass percentage: 8-10% RE, 0.1-3% Y, 0.2-0.4% Mg, and the balance is Al element and inevitable impurity elements.

Further, the RE is one of Ce and La or a combination of both.

Compared with the prior art, one of the innovative ideas of the present invention to provide Al-RE-Y-Mg alloy suitable for pressure/gravity casting is as follows: the alloy adopts Y element mixed with La/Ce element, and Y and La/Ce are the same. Inexpensive rare earth elements, on the one hand, the mixing of Y element and La/Ce element can refine the grains well, and at the same time, it can change the morphology of the Al11RE3 phase from semi-stripe to fibrous, improving the pure Al-La The segregation of Al11RE3 phase in /Ce alloy has a more uniform structure and better performance. On the other hand, the mixed addition overcomes the formation of primary Al11RE3 phase when the RE content is higher than 8%, greatly improves the elongation and strength of the alloy, and expands the addition range of rare earth content. If the mixture of Sc and La/Ce rare earth is used, the effect of Sc refining the Al11RE3 phase is very limited. In addition, Sc is expensive and not suitable for a large amount of addition; while Y has a remarkable effect of refining the Al11RE3 phase, and the mechanism of action between Y and La/Ce is completely different from that of Sc.

The second innovative idea of the present invention to provide an Al-RE-Y-Mg alloy suitable for pressure/gravity casting is as follows: the present invention finds for the first time that the mixed addition of rare earth elements and Y increases the number of strengthening phases, making the Al11RE3 phase with high heat resistance The content is more, it is finer, the distribution is more uniform, and it can play its role of high heat resistance. The addition of Zr can also refine the Al11RE3 phase, but the addition of Zr cannot exceed 0.3 wt.%, otherwise the primary Al3Zr phase will be generated. However, the addition of Y content can be mixed with La/Ce, and the corresponding primary phase will not be generated. The RE content is increased from 8% to 14% (RE+Y), which greatly increases the content of the strengthening phase without affecting its fluidity. and casting properties.

The third innovative idea of the present invention to provide Al-RE-Y-Mg alloy suitable for pressure/gravity casting is: on the one hand, RE element and Y element have no solubility in aluminum, and all generate intermetallic compounds, pure aluminum and rare earth metals All compounds have good thermal conductivity, which ensures the high thermal conductivity of the aluminum alloy. On the other hand, through the mixing of RE and Y elements, the metal part compound is refined, so that the aluminum matrix can be connected, and its thermal conductivity is also improved.

The fourth innovative idea of the present invention to provide Al-RE-Y-Mg alloy suitable for pressure/gravity casting is: adding an appropriate amount of Mg element can achieve the effects of solid solution strengthening and possible precipitation strengthening in the alloy, and has fine The effect of crystal strengthening further improves the strength of the alloy. Adding an appropriate amount of Mg also does not affect the fluidity and casting properties, nor does it affect the elongation of the alloy.

The present invention also provides a preparation method of the Al-RE-Y-Mg alloy, which comprises the following steps:

S1, according to described Al-RE-Y-Mg alloy composition and stoichiometric ratio, calculate the consumption of required aluminum ingot, magnesium ingot, Al-RE intermediate alloy and Al-Y intermediate alloy;

S2. After all the aluminum ingots are melted, the temperature is raised to 740-760 °C, the Al-RE master alloy and the Al-Y master alloy are added, and the temperature is kept constant at 740-760 °C, and stirred until all melted;

S3. After the intermediate alloy is completely melted, the temperature is lowered to 700-710°C, the magnesium ingot is added, and the temperature is kept constant at 700-710°C, stirred until all melted, and kept for 25-35 minutes;

S4. After adding a refining agent for refining, the furnace temperature is raised to 745-755 °C and kept for 10-20 minutes to promote the settlement of inclusions to obtain an aluminum alloy melt;

S5. Cool the aluminum alloy melt to between 700 and 740°C, skim off the surface scum, and die-cast the melt through a die-casting machine or cast the melt into an aluminum alloy that has been preheated to 180-250°C by gravity casting. In the mold, the Al-RE-Y-Mg alloy is obtained.

In step S1, aluminum ingots, magnesium ingots, Al-RE intermediate alloys and Al-Y intermediate alloys are all removed oxide layers, dried and preheated to 190-210 °C; then the required dosage is calculated. The aluminum ingots are industrial pure aluminum ingots, and the magnesium ingots are industrial pure magnesium ingots.

In step S2, after the aluminum ingots accounting for 22-28% of the crucible height are melted into a molten pool at 715-725° C., the remaining aluminum ingots are added. Al-RE and Al-Y master alloys are added in 2 to 4 times.

In step S4, when the pressure casting scheme is adopted, 40 to 60 minutes before pressure casting, after all the alloys are melted, a refining agent is added for refining, and the furnace temperature is raised to 750°C and kept for 10 to 20 minutes to promote the settlement of inclusions, obtain aluminum alloy melt;

Further, in step S1, the Al-RE master alloy is one or both of Al-20Ce and Al-20La, and the Al-Y master alloy is Al-10Y.

Further, in step S4, the refining agent components are: 55% KCl, 30% NaCl, 15% BaCl ₂ by mass percentage.

Further, in step S4, the added amount of the refining agent is 1.0-2.5% of the total weight of the raw materials.

Further, in step S4, the refining temperature is 720-750°C, and the stirring time of the refining treatment is 10-15 min.

Further, in step S5, the die-casting temperature is 700-740°C; the casting temperature is 710-740°C.

Further, in step S5, the die-casting speed is 1-8 m/s.

The advantages of the preparation method of the Al-RE-Y-Mg alloy suitable for pressure/gravity casting provided by the present invention are: (1) RE and Y are both added in the form of intermediate alloys, there is no easy-to-burn element, and the composition control is easy, The smelting process is simple and easy to control; (2) the refining treatment adopts a special refining agent without MgCl2, which further reduces the burning loss of rare earth Y during the refining process; (3) does not require subsequent heat treatment, which simplifies the process and improves energy utilization. rate and production efficiency. (4) Ce, La and Y are all cheap rare earth elements, which are suitable for mass production and meet industrial needs.

Compared with the prior art, the present invention has the following beneficial effects:

1) The Al-RE-Y-Mg alloy of the present invention is a high heat-resistant alloy obtained by pressure casting, with a room temperature tensile strength of 260 MPa and an elongation of 11%; after being kept at 250°C for 200 hours, its high-temperature tensile strength reaches 130 MPa , 19% elongation, excellent normal temperature strength and high temperature strength;

2) The Al-RE-Y-Mg alloy of the present invention is gravity-cast to obtain a high thermal conductivity and corrosion-resistant alloy, the room temperature tensile strength reaches 145MPa, the elongation is 14%, the thermal conductivity is 178W/(m·K), and the comprehensive performance is excellent;

3) The preparation method provided by the present invention has the advantages of simple process, high efficiency, suitable for large-scale production, etc., and meets the high-end demand for lightweight development in aerospace, military, automobile and other industries.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

Fig. 1 is the metallographic structure diagram of the high-strength, toughness and heat-resistant die-casting Al-RE-Y-Mg alloy obtained by pressure casting in Example 3;

Fig. 2 is the metallographic structure diagram of high thermal conductivity and corrosion-resistant Al-RE-Y-Mg alloy obtained by gravity casting in Example 3;

FIG. 3 is a metallographic structure diagram of the alloy obtained by pressure casting in Comparative Example 2. FIG.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Example 1

The weight percentage of an Al-RE-Y-Mg alloy is: according to the theoretical ratio, 10wt% Ce, 4wt% Y, 0.3wt% Mg, and the rest are Al element and inevitable impurity elements.

The preparation method is as follows: (1) after properly considering the burning loss, according to the above-mentioned Al-RE-Y-Mg alloy composition and stoichiometric ratio, calculate the amount of the required raw materials; Both 20Ce and Al-10Y master alloys have their oxide layers removed, dried and preheated to 200°C; the amount of raw materials required is calculated according to the composition and stoichiometric ratio of the alloys; (2) the industrial pure aluminum ingots that account for 25% of the crucible height After melting into a molten pool at 720°C, the remaining aluminum ingots are added; (3) After all the aluminum ingots are melted, the temperature is raised to 750°C, and the Al-20Ce and Al-10Y master alloys are added in 2 to 4 times, and the temperature is maintained. Keep the temperature constant at 750°C, stir until all melted, (4) after the master alloy is completely melted, cool down to 700°C, add industrial pure magnesium ingots to the melt, and keep the temperature constant at 700°C, stir until all melted, and Hold for 30 minutes; (5) 40-60 minutes before pressure casting or gravity casting, after all the intermediate alloys are melted, add a refining agent of 1% by weight of raw materials for refining, refining temperature is 730 ℃, refining treatment stirring time 10min, The components of the refining agent are: 55% KCl, 30% NaCl, 15% BaCl ₂ by mass percentage, and the furnace temperature is raised to 750° C. and kept for 10 minutes to promote inclusion settlement to obtain an aluminum alloy melt; (6) the described The aluminum alloy melt was cooled to 720°C, the surface dross was skimmed off, and the melt was pressed into a metal mold that had been preheated to 180°C by a die-casting machine, and the die-casting speed was 4m/s to obtain the high-strength, toughness, and heat-resistant die-casting Al -RE-Y-Mg alloy; or pour the melt into a metal mold preheated to 250° C. by gravity casting to obtain the gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance.

The prepared pressure casting Al-RE-Y-Mg alloy with high strength, toughness and heat resistance was respectively subjected to a. room temperature tensile test;

b. After heat exposure at 250°C and 200 hours, a high temperature tensile property test was performed at 200°C. In this example, the room temperature tensile strength of the high-strength, toughness and heat-resistant Al-RE-Y-Mg alloy is 269MPa, the yield strength is 168MPa, and the elongation is 7.5%; the high-temperature tensile strength at 250°C is 145MPa, and the elongation is 15%.

The prepared gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance was respectively subjected to a. room temperature tensile test; b. room temperature thermal conductivity test. In this example, the gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance has a room temperature tensile strength of 160 MPa, a yield strength of 88 MPa, an elongation of 11.0%, and a thermal conductivity of 160 W/(m·K).

Example 2

The weight percentage of an Al-RE-Y-Mg alloy is: according to the theoretical ratio, 4wt% La, 0.3wt% Y, 0.2wt% Mg, and the rest are Al element and inevitable impurity elements.

Its preparation method is (1) after proper consideration of burning loss, according to the above-mentioned Al-RE-Y alloy composition and stoichiometric ratio, calculate the amount of required raw materials; -10Y master alloys are all removed the oxide layer and dried and preheated to 200℃; according to the composition of the alloy and the stoichiometric ratio, calculate the amount of the required raw materials; (2) put the industrial pure aluminum ingots that account for 25% of the crucible height at 720℃ After melting into a molten pool, the remaining aluminum ingots are added; (3) after the aluminum ingots are all melted, the temperature is raised to 750 ° C, and the Al-20La and Al-10Y master alloys are added in 2 to 4 times, and the temperature is kept constant at 750 ℃, stir until all melted, (4) after the master alloy is completely melted, cool down to 700 ℃, add industrial pure magnesium ingot to the melt, keep the temperature constant at 700 ℃, stir until all melted, and keep warm for 30 minutes (5) 40-60 minutes before pressure/gravity casting, when all the intermediate alloys are melted, add a refining agent of 2% by weight of raw materials for refining, refining temperature 750 ° C, refining treatment stirring time 15min, refining agent components According to the mass percentage: 55% KCl, 30% NaCl, 15% BaCl ₂ , the furnace temperature is raised to 750° C. and kept for 10 minutes to promote inclusion settlement to obtain an aluminum alloy melt; (6) the aluminum alloy melt is Cool down to 740°C, skim off the surface scum, press the melt into a metal mold that has been preheated to 200°C by a die-casting machine, and the die-casting speed is 2m/s to obtain the high-strength, toughness and heat-resistant die-casting Al-RE-Y -Mg alloy; or pour the melt into a metal mold preheated to 200° C. by gravity casting to obtain the gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance.

The prepared pressure casting Al-RE-Y-Mg alloy with high strength, toughness and heat resistance was respectively subjected to a. room temperature tensile test; b. high temperature tensile property test at 250 ℃ after heat exposure at 250 ℃ and 200 hours. In this example, the room temperature tensile strength of the high-strength, toughness and heat-resistant Al-RE-Y-Mg alloy is 230MPa, the yield strength is 130MPa, and the elongation is 18.2%; the high-temperature tensile strength at 250°C is 90MPa, and the elongation is 25%.

The prepared gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance was respectively subjected to a. room temperature tensile test; b. room temperature thermal conductivity test. In this example, the gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance has a room temperature tensile strength of 130 MPa, a yield strength of 73 MPa, an elongation of 19.0%, and a thermal conductivity of 195 W/(m·K).

Example 3

The weight percentage of an Al-RE-Y-Mg alloy is: according to the theoretical ratio, 5wt% La, 3wt% Ce, 3wt% Y, 0.4wt% Mg, and the rest are Al element and inevitable impurity elements.

Its preparation method is (1) after proper consideration of burning loss, according to the above-mentioned Al-RE-Y alloy composition and stoichiometric ratio, calculate the amount of required raw materials; Both -20Ce and Al-10Y master alloys have their oxide layers removed and dried and preheated to 200°C; according to the composition of the alloy and the stoichiometric ratio, calculate the amount of raw materials required; (2) industrially pure aluminum that accounts for 25% of the crucible height After the ingot is melted into a molten pool at 720°C, the remaining aluminum ingots are added; (3) after all the aluminum ingots are melted, the temperature is raised to 750°C, and the Al-20La, Al-20Ce and Al-10Y master alloys are divided into 2 to 4 times. Add, and keep the temperature constant at 750 °C, and stir until all melted. (4) After the intermediate alloy is completely melted, cool down to 700 °C, add industrial pure magnesium ingots to the melt, and keep the temperature constant at 700 °C, and stir (5) 40-60 minutes before pressure/gravity casting, when all the intermediate alloys are melted, add a refining agent with 1.5% by weight of raw materials for refining, refining temperature is 740 ° C, refining treatment The stirring time is 12min, the components of the refining agent are: 55% KCl, 30% NaCl, 15% BaCl ₂ by mass percentage, the furnace temperature is raised to 750 ℃ and kept for 10 minutes to promote the inclusions sedimentation, and the aluminum alloy melt is obtained; (6 ) Cool the aluminum alloy melt to 720°C, skim off the surface scum, press the melt into a metal mold that has been preheated to 250°C by a die casting machine, and the die casting speed is 1 m/s to obtain the high strength and toughness. Heat-resistant die-casting Al-RE-Y-Mg alloy; or pour the melt into a metal mold that has been preheated to 250°C by gravity casting to obtain the gravity-casting Al-RE-Y-Mg with high thermal conductivity and corrosion resistance alloy.

The prepared pressure casting Al-RE-Y-Mg alloy with high strength, toughness and heat resistance was respectively subjected to a. room temperature tensile test; b. high temperature tensile property test at 250 ℃ after heat exposure at 250 ℃ and 200 hours. In this example, the room temperature tensile strength of the high-strength, toughness and heat-resistant Al-RE-Y-Mg alloy is 260MPa, the yield strength is 145MPa, and the elongation is 11%; the high-temperature tensile strength at 250°C is 130MPa, and the elongation is 19%. The metallographic structure of the alloy is shown in Figure 1. It can be seen from Figure 1 that the eutectic Al11RE3 phase in the structure is uniform and fine, and there is almost no primary Al11RE3 phase, which makes the alloy have better heat resistance and strength. The presence of rose-like pure aluminum dendrites in the crystalline phase provides the alloy with high toughness.

The prepared gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance was respectively subjected to a. room temperature tensile test; b. room temperature thermal conductivity test. In this example, the gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance has a room temperature tensile strength of 145 MPa, a yield strength of 85 MPa, an elongation of 14.0%, and a thermal conductivity of 178 W/(m·K). The metallographic structure of the alloy is shown in Fig. 2. From Fig. 2, it can be seen that there is almost no primary Al11RE3 phase in the structure, and the aluminum dendrite is dendritic. The Al11RE3 phase in the eutectic structure is uniformly distributed and has certain dendritic properties. This allows the Al in the alloy to be interconnected, with excellent thermal conductivity and good elongation.

Example 4

The weight percentage of an Al-RE-Y-Mg alloy is: according to the theoretical ratio, 8wt% La, 1wt% Ce, 2wt% Y, 0.2wt% Mg, and the rest are Al element and inevitable impurity elements.

Its preparation method is (1) after proper consideration of burning loss, according to the above-mentioned Al-RE-Y alloy composition and stoichiometric ratio, calculate the amount of required raw materials; Both -20Ce and Al-10Y master alloys have their oxide layers removed and dried and preheated to 200°C; according to the composition of the alloy and the stoichiometric ratio, calculate the amount of raw materials required; (2) industrially pure aluminum that accounts for 25% of the crucible height After the ingot is melted into a molten pool at 720°C, the remaining aluminum ingots are added; (3) after all the aluminum ingots are melted, the temperature is raised to 750°C, and the Al-20La, Al-20Ce and Al-10Y master alloys are divided into 2 to 4 times. Add, and keep the temperature constant at 750 °C, and stir until all melted. (4) After the intermediate alloy is completely melted, cool down to 700 °C, add industrial pure magnesium ingots to the melt, and keep the temperature constant at 700 °C, and stir (5) 40-60 minutes before pressure/gravity casting, when all the intermediate alloys are melted, add a refining agent with 2.5% of the weight of the raw materials for refining, the refining temperature is 750 ° C, the refining treatment The stirring time is 10min, the components of the refining agent are: 55% KCl, 30% NaCl, 15% BaCl ₂ by mass percentage, the furnace temperature is raised to 750 ° C and kept for 10 minutes to promote the inclusions to settle, and the aluminum alloy melt is obtained; (6 ) Cool the aluminum alloy melt to 720°C, skim off the surface scum, press the melt into a metal mold that has been preheated to 240°C by a die casting machine, and the die casting speed is 5m/s to obtain the high strength and toughness Heat-resistant die-casting Al-RE-Y-Mg alloy; or pour the melt into a metal mold that has been preheated to 240°C by gravity casting to obtain the gravity casting Al-RE-Y-Mg with high thermal conductivity and corrosion resistance alloy.

The prepared pressure casting Al-RE-Y-Mg alloy with high strength, toughness and heat resistance was respectively subjected to a. room temperature tensile test; b. high temperature tensile property test at 250 ℃ after heat exposure at 250 ℃ and 200 hours. In this example, the room temperature tensile strength of the high-strength, toughness and heat-resistant Al-RE-Y-Mg alloy is 240MPa, the yield strength is 135MPa, and the elongation is 12%; the high-temperature tensile strength at 250°C is 125MPa, and the elongation is 18%.

The prepared gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance was respectively subjected to a. room temperature tensile test; b. room temperature thermal conductivity test. In this example, the gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance has a room temperature tensile strength of 135 MPa, a yield strength of 78 MPa, an elongation of 16.0%, and a thermal conductivity of 181 W/(m·K).

Example 5

The weight percentage of an Al-RE-Y-Mg alloy is: according to the theoretical ratio, 10wt% La, 1wt% Y, 0.3wt% Mg, and the rest are Al element and inevitable impurity elements.

Its preparation method is (1) after proper consideration of burning loss, according to the above-mentioned Al-RE-Y alloy composition and stoichiometric ratio, calculate the amount of required raw materials; -10Y master alloys are all removed the oxide layer and dried and preheated to 200℃; according to the composition of the alloy and the stoichiometric ratio, calculate the amount of the required raw materials; (2) put the industrial pure aluminum ingots that account for 25% of the crucible height at 720℃ After melting into a molten pool, the remaining aluminum ingots are added; (3) after the aluminum ingots are all melted, the temperature is raised to 750 ° C, and the Al-20La and Al-10Y master alloys are added in 2 to 4 times, and the temperature is kept constant at 750 ℃, stir until all melted, (4) after the master alloy is completely melted, cool down to 700 ℃, add industrial pure magnesium ingot to the melt, keep the temperature constant at 700 ℃, stir until all melted, and keep warm for 30 minutes (5) 40-60 minutes before pressure/gravity casting, when all the intermediate alloys are melted, add a refining agent of 1% by weight of raw materials for refining, refining temperature 720 ° C, refining treatment stirring time 10min, refining agent components According to the mass percentage: 55% KCl, 30% NaCl, 15% BaCl ₂ , the furnace temperature is raised to 750° C. and kept for 10 minutes to promote inclusion settlement to obtain an aluminum alloy melt; (6) the aluminum alloy melt is Cool down to 740°C, skim off the surface scum, press the melt into a metal mold that has been preheated to 250°C through a die-casting machine, and the die-casting speed is 8m/s to obtain the high-strength, toughness and heat-resistant die-casting Al-RE-Y -Mg alloy; or pour the melt into a metal mold preheated to 250° C. by gravity casting to obtain the gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance.

The prepared pressure casting Al-RE-Y-Mg alloy with high strength, toughness and heat resistance was respectively subjected to a. room temperature tensile test; b. high temperature tensile property test at 250 ℃ after heat exposure at 250 ℃ and 200 hours. In this example, the room temperature tensile strength of the high-strength, toughness and heat-resistant Al-RE-Y-Mg alloy is 265MPa, the yield strength is 141MPa, and the elongation is 9.2%; the high-temperature tensile strength at 250°C is 128MPa, and the elongation is 16%.

The prepared gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance was respectively subjected to a. room temperature tensile test; b. room temperature thermal conductivity test. In this example, the gravity casting Al-RE-Y-Mg alloy with high thermal conductivity and corrosion resistance has a room temperature tensile strength of 138 MPa, a yield strength of 80 MPa, an elongation of 15.0%, and a thermal conductivity of 180 W/(m·K).

Comparative Example 1

This comparative example provides an alloy whose weight percentages are: according to the theoretical ratio, 4wt% La, 0.3wt% Ti, 0.2wt% Mg, and the rest are Al element and unavoidable impurity elements. The composition and preparation are basically the same as those in Example 2, the only difference is that 0.3 wt % Ti is added in this comparative example instead of 0.3 wt % Y added in Example 2.

The obtained pressure casting alloys were respectively subjected to a. room temperature tensile test; b. high temperature tensile property test at 250°C after heat exposure at 250°C and 200 hours. In this comparative example, the room temperature tensile strength of the alloy is 150MPa, the yield strength is 105MPa, and the elongation is 10.9%; the high temperature tensile strength at 250°C is 62MPa, and the elongation is 20%.

The prepared gravity casting alloys were respectively subjected to a. room temperature tensile test; b. room temperature thermal conductivity test. In this comparative example, the room temperature tensile strength of the alloy is 110MPa, the yield strength is 59MPa, the elongation is 17.0%, and the thermal conductivity is 150W/(m·K).

Comparative Example 2

The comparative example provides an alloy whose weight percentages are: according to the theoretical ratio, 5wt% La, 3wt% Ce, 0.2wt% Ti, 0.4wt% Mg, and the rest are Al elements and inevitable impurity elements. The composition and preparation are basically the same as those in Example 3, the only difference is that 0.2 wt % Ti is added in this comparative example instead of 3 wt % Y added in Example 3.

The obtained pressure casting alloys were respectively subjected to a. room temperature tensile test; b. high temperature tensile property test at 250°C after heat exposure at 250°C and 200 hours. In this comparative example, the room temperature tensile strength of the alloy is 190 MPa, the yield strength is 125 MPa, and the elongation is 10%; the high temperature tensile strength at 250° C. is 70 MPa, and the elongation is 18%.

The metallographic structure of the alloy is shown in Figure 3. There is a primary Al11RE3 phase in the structure, and the eutectic phase segregation is serious and lath-like, which affects the performance of the alloy.

The specific embodiments of the present invention have been described above in detail. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various variations or modifications within the scope of the claims, which do not affect the essential content of the present invention.

Claims (10)

1. An Al-RE-Y-Mg alloy is characterized by comprising the following elements in percentage by mass: 4-10% of RE, 0.3-4% of Y, 0.2-0.4% of Mg, and the balance of Al element and inevitable impurity elements.

2. The Al-RE-Y-Mg alloy of claim 1, consisting of, in mass percent: 8-10% of RE, 0.3-4% of Y, 0.2-0.4% of Mg, and the balance of Al element and inevitable impurity elements.

3. The Al-RE-Y-Mg alloy of claim 1 or 2, wherein RE is one or a combination of two of Ce and La.

4. A method of producing the Al-RE-Y-Mg alloy according to any one of claims 1 to 3, characterized in that it comprises the following steps:

s1, calculating the consumption of the needed aluminum ingot, magnesium ingot, Al-RE intermediate alloy and Al-Y intermediate alloy according to the Al-RE-Y-Mg alloy components and the stoichiometric ratio;

s2, heating to 740-760 ℃ after the aluminum ingot is completely melted, adding the Al-RE intermediate alloy and the Al-Y intermediate alloy, keeping the temperature constant at 740-760 ℃, and stirring until the aluminum ingot is completely melted;

s3, cooling to 700-710 ℃ after the intermediate alloy is completely melted, adding the magnesium ingot, keeping the temperature constant at 700-710 ℃, stirring until the intermediate alloy is completely melted, and keeping the temperature for 25-35 minutes;

s4, adding a refining agent for refining, raising the temperature of the furnace to 745-755 ℃, preserving the temperature, standing for 10-20 minutes to promote the settlement of inclusions, and obtaining an aluminum alloy melt;

and S5, cooling the aluminum alloy melt to 700-740 ℃, skimming surface scum, and die casting the melt into a die preheated to 180-250 ℃ by a die casting machine or gravity casting to obtain the Al-RE-Y-Mg alloy.

5. The method of claim 4, wherein in step S1, the Al-RE intermediate alloy is one or both of Al-20Ce and Al-20La, and the Al-Y intermediate alloy is Al-10Y.

6. The method for preparing the Al-RE-Y-Mg alloy according to claim 4, wherein in step S4, the refining agent comprises the following components in percentage by mass: 55% KCl, 30% NaCl, 15% BaCl₂。

7. The method of manufacturing the Al-RE-Y-Mg alloy according to claim 4, wherein in step S4, the amount of the refining agent added is 1.0-2.5% by weight of the total weight of the raw materials.

8. The method for producing an Al-RE-Y-Mg alloy according to claim 4, wherein in step S4, the temperature of refining is 720 to 750 ℃, and the stirring time of the refining is 10 to 15 min.

9. The method for preparing the Al-RE-Y-Mg alloy according to claim 4, wherein in step S5, the die casting temperature is 700-740 ℃; the casting temperature is 710-740 ℃.

10. The method of producing an Al-RE-Y-Mg alloy according to claim 4, wherein in step S5, the die casting speed is 1 to 8 m/S.

Images