CN113755727A

CN113755727A - Heat-resistant aluminum-based composite material and preparation method thereof

Info

Publication number: CN113755727A
Application number: CN202110969762.2A
Authority: CN
Inventors: 潘利文; 曾广凯; 崔君阁; 王雨辰; 徐浩楠; 赵艳君; 胡治流
Original assignee: Guangxi University
Current assignee: Guangxi University
Priority date: 2021-08-23
Filing date: 2021-08-23
Publication date: 2021-12-07
Anticipated expiration: 2041-08-23
Also published as: CN113755727B

Abstract

The invention discloses a heat-resistant aluminum-based composite material, which comprises the following elements in percentage by mass: al (Al)₃7-11% of Zr, 4-8% of Cu, 1-3% of Ni, 0.3-0.7% of V and the balance of Al. The invention also discloses a preparation method of the material. The aluminum-based composite material provided by the invention has very good high-temperature mechanical properties, has higher tensile strength at a high temperature of 350 ℃ compared with the existing heat-resistant aluminum alloy material, and is very suitable for the requirements of heat-resistant parts in the fields of automobiles, weapons, aviation, aerospace, ships and the like. The preparation process of the aluminum-based composite material is simple, and the preparation process time is shortThe process is reliable, the production cost is greatly saved, and the large-scale industrial production is easy to realize.

Description

Heat-resistant aluminum-based composite material and preparation method thereof

Technical Field

The invention relates to a preparation method of an aluminum alloy composite material, in particular to a heat-resistant aluminum matrix composite material and a preparation method thereof.

Background

The heat-resistant aluminum alloy has the advantages of small density, high temperature and specific strength, creep resistance, oxidation resistance and the like, and is widely applied to the fields of ships, weapons, aviation, aerospace, automobiles and the like, such as pistons, cylinder sleeves, connecting rods, boxes and cylinder covers of tank armored vehicle engines, missile shells and empennages, aeroengine cylinders, compressor blades, aircraft skins and the like. The traditional casting heat-resistant aluminum alloy mainly comprises an Al-Si system, an Al-Cu system, an Al-Si-Cu system, an Al-Mg system and an Al-Si-Mg system, and the traditional casting heat-resistant aluminum alloy is developed in an extending way and comprises an Al-Si-Cu-Mg system, an Al-Si-Cu-Mg-Ni system, an Al-Cu-Mg-Ag system and the like. The mechanical properties of the alloy are improved by adding different alloy elements to obtain different strengthening phases or strengthening modes in the alloy of different systems. At present, the high-temperature strength, the thermal fatigue resistance and the like of the traditional casting heat-resistant aluminum alloy are close to the extreme state, and the high-efficiency development requirement of a novel high-power engine, such as a high-power armored car engine, can not be met. The main reason is that the strengthening phase in the aluminum alloy has insufficient high-temperature thermal stability, is easy to coarsen or dissolve at high temperature to lose the strengthening effect, and the service temperature of the Al-Si series heat-resistant aluminum alloy is generally not more than 230 ℃. Adding Mg into Al-Si alloy, aging and precipitating Mg₂Si phase, although improving the room temperature strength of the material, due to Mg₂The thermal stability temperature of the Si phase is about 180 ℃, so that the cast Al-Mg-Si alloy has low heat resistance and the working temperature is generally lower than 185 ℃. Al-Cu system or Al-Si system alloy with Cu added can precipitate theta' -Al by solid solution-aging₂The Cu phase, which has a thermal stability temperature of about 225 ℃, can improve the high temperature strength of the material, but due to the limitation of the thermal stability of the strengthening phase, the overall high temperature strength level of Al-Cu or Al-Si-Cu series cast aluminum alloys is not high, and generally onlyCan work below 225 ℃. However, a piston, which is one of the key components in the combustion chamber of an engine, needs to be in contact with high-temperature gas of 350-400 ℃ (even higher) for a long time and bear the thermo-mechanical fatigue effect of 25-300 ℃, so that the traditional cast heat-resistant aluminum alloy cannot meet the temperature bearing requirement of the engine component under the high-temperature condition of 300-400 ℃. The development of high-performance heat-resistant aluminum alloy with high strength and better high-temperature creep resistance at high temperature to meet the heat-resistant requirement of a novel high-efficiency engine, and the partial replacement of expensive titanium alloy is an important subject in the research field of novel aluminum alloy at home and abroad in about 20-30 years. In the eighties of the last century, in order to meet the demand of advanced fighters for materials, the united states air force has focused attention on developing aluminum alloys that can replace titanium alloys at temperatures below 350 ℃. According to research summary of recent 20 years, introduction of a high-strength, high-thermal stability and high-volume fraction uniformly distributed micron or nanometer scale strengthening phase into an aluminum alloy matrix is a fundamental way for improving high-temperature mechanical properties of the aluminum alloy matrix.

The introduction of high heat stability strengthening phase particles into cast aluminum alloy has two important approaches, one is to add new alloying elements to lead the alloy to pass through eutectic or peritectic reaction, or to precipitate new high temperature strengthening phase after aging; the other approach is to add high-strength and high-thermal-stability ceramic reinforcing particles by a liquid stirring method. In the first method, trace alloying elements with high melting point and low thermal diffusion coefficient, such as Ti, V, Zr, Cr, Mn, Fe, Co, Ni, Nb, Ce, Er, etc. are generally added to form a high melting point intermetallic compound strengthening phase, such as Al, by solid solution strengthening or reaction with the matrix₃Ni、Al₃CuNi、Al₃(Ni, Cu)₂、Al₁₂(Fe,V)₃Si、Al₃Ti、Al₃Zr、Al₃V、Al₃Sc、Al₃Er, etc., but this method is limited by the alloy equilibrium solidification eutectic, the size of peritectic point components and the ultimate solid solubility of elements, so that the volume fraction of the final strengthening phase is very limited, and the volume fraction of the strengthening phase is generally difficult to exceed 10%, such as Al-Al₃Ni eutectic system, about 6% of eutectic point component of Ni, and Al in the structure solidified along the eutectic point component₃The Ni phase is only 9.7% by weight and has a volume fraction of about 6.8%, so that the eutectic strengthening phase Al alone₃Ni cannot greatly improve the high-temperature performance of the alloy. In the Al-Zr alloy and the Al-V alloy, Al is included₃Zr and Al₃V is recognized as having high temperature thermal stability of 300 ℃ or higher, but Zr and V have extremely low solid solubility in aluminum matrix, and the ultimate solid solubility is only C_αp-Zr0.28 wt% and C_αp-VAnd the content is approximately equal to 0.56 wt%, so that the volume fraction of the strengthening phase generated after aging is extremely small, and if the content exceeds the limit solid solubility, peritectic reaction can occur under the normal solidification condition to generate a coarse peritectic primary phase, and the plasticity and the strength of the alloy are seriously damaged. The method for improving the solid solubility by the ultra-fast solidification method to improve the precipitation quantity of the strengthening phase after aging is a development direction of research, but is limited by experimental conditions and sample size, and the current research work is in a laboratory stage.

In the case where the volume fraction of the strengthening phase cannot be increased, it is also an important way to increase the yield strength of the material from the viewpoint of reducing the particle size d alone, so that the thermally stable nano-precipitation strengthening phase is a hot spot studied in recent years. Wherein, transition metal elements Zr, Ti and V with low thermal diffusion coefficient in aluminum matrix react with aluminum to precipitate Al₃Zr、Al₃Ti and Al₃V has been the focus of research, and is a high heat-stable strengthening phase which is considered to be most promising for the aluminum alloy to reach the use temperature of 300 to 500 ℃. Al (Al)₃The melting point of Ti is 1350 ℃ and the density of Ti is 3.36g/cm³Elastic modulus of 220GPa, and balanced crystal structure of stable ordered tetragonal D0₂₂Structure, metastable face-centered cubic L1₂Structural Al₃Ti is converted into stable tetragonal D0 at high temperature₂₂-Al₃Ti, both structures being in coherent relationship with the aluminum matrix, D0₂₂-Al₃The thermal stability of Ti is as high as 500 ℃, and spheroidization of the phase begins to occur only when the phase is annealed at 600 ℃. Al (Al)₃Zr has high melting point (1580 ℃) and high elastic modulus (196GPa) and balances the tetragonal crystal structure D0₂₃-Al₃The Zr phase and the Al matrix form a semi-coherent interface structure, and the metastable face center is square L1₂-Al₃Zr phase and Al matrix form a coherent interface structure, and a balanced tetragonal structure D0₂₃-Al₃Zr phase has lower lattice mismatch with aluminum matrix, i.e. lower interfacial energy, metastable center L1₂-Al₃The thermal stability of Zr reaches 425 ℃, and the tetragonal crystal structure D0 is stabilized₂₃-Al₃The Zr phase has higher thermal stability temperature, when V is dissolved into Al₃Formation of Al in Zr₃The thermal stability of (Zr, V) is more than 500 ℃. Al (Al)₃V has a melting point of 1360 ℃ and a density of 3.44g/cm³The stable phase is a square D0₂₂Structure, when dissolved in Ti or Zr forms D0 which is more stable and less mismatched with aluminum matrix₂₂-Al₃(V_x,Ti_1-x) Or D0₂₂-Al₃(V_x,Zr_1-x) And (4) phase(s). Viewed from the phase diagram, Al₃Ti、Al₃Zr and Al₃The three phases V are primary phases of peritectic reaction, and the peritectic reaction temperature is slightly higher than the melting point of aluminum, so the phase transition temperature is higher than that of eutectic aluminum alloy, and the eutectic aluminum alloy has more potential than that of eutectic aluminum alloy when being used as a high-temperature material. P. Sepehrband et Al studied the influence of trace Zr (0.15 wt.%) on the microstructure and mechanical properties of A319 cast aluminum alloy after aging, and found that the addition of Zr refined the alpha-Al dendrite spacing and precipitated L1 with average particle size of 210-250 nm after aging₂-Al₃Zr strengthens the phase particles, thereby improving the hardness, elastic limit, tensile strength and wear resistance of the alloy. JIA Zhi-hong et Al investigated the precipitation behavior of Al-5Cu-0.2Zr-0.1Ti-0.2V alloys at 500 ℃ over 5h, and showed that the coherent L1 having an average grain size of 11.6nm₂-Al₃The (Zr, Ti, V) phases are uniformly and densely distributed on the alpha-Al dendrite stems, but are sparser and unevenly distributed among dendrites (see a diagram in FIG. 6); after the aging time is prolonged to 20h, metastable L1₂-Al₃(Zr, Ti, V) is converted into stable tetragonal DO₂₃-Al₃(Zr, Ti, V), analysis suggests that the presence of Cu promotes this transition. Al (Al)₃A similar situation also occurs in the study of k.e. kiniping, for the difference in the homogeneity of the precipitation distribution of the Zr phase on the dendrite arms and between the dendrites (see graph b in fig. 6). S.k.shaha et al added trace Cr (0.47 wt.%), Ti (0.39 wt.%)V (0.39 wt.%) and Zr (0.25 wt.%) modify the Al-7Si-1Cu-0.5Mg alloy, and the solidification structure of the alloy appears (Al, Si)₃Ti、 (Al,Si)₃(Ti,Zr)、(Al,Si)₃(Ti, V, Zr) and (Al, Si)₃After T6 heat treatment, the tensile strength and yield strength of the modified alloy at 300 ℃ are improved to 196MPa and 184MPa respectively, and the main reason for improving the high-temperature performance is that the high-temperature heat-stable strengthening phase effectively inhibits dislocation slippage in the process of tensile load. The Yangyang Fan et Al introduce trace Zr and V in Al-6Ni eutectic alloy, and compare the structure and performance of Al-0.4Zr-0.4V and Al-6Ni-0.4Zr-0.4V alloys, and the results show that the Al-0.4Zr-0.4V alloys are aged to intensively precipitate nanoscale L1 on alpha-Al dendrite arms₂-Al₃(Zr_x,V_1-x) Phase, but the phase precipitation is significantly reduced in the peripheral region of the dendrite arms, whereas for Al-6Ni-0.4Zr-0.4V alloys, L1₂-Al₃(Zr_x,V_1-x) The precipitation of the nanophase is uniformly distributed on the whole aluminum matrix, the particle size is smaller than that of the precipitation of the nanophase in the Al-0.4Zr-0.4V alloy, the average particle size is about 5-6 nm, and the room temperature yield strength of the Ni-containing alloy is improved by 30MPa compared with that of the Ni-free alloy. It can be seen that the nanoscale L1 is precipitated after the current addition of trace transition metal elements and the aging₂-Al₃The research on strengthening of M relative to aluminum matrix is greatly advanced, but still in the basic research stage, and the research on the mechanical properties at high temperature of 300-500 ℃ is still lacked, such as tensile strength, creep resistance and failure mechanism at the temperature of more than 400 ℃, and the like. In addition, the problems that the distribution of the nano-phase precipitated by aging is uneven and the volume fraction of the precipitated phase is small are all problems to be solved.

Metastable state L1₂-Al₃Zr strengthening of aluminum alloys by Zr microalloying and aging has been widely reported, however, the use of higher thermal stability tetragonal D0₂₃-Al₃There are few reports of Zr for high temperature strengthening of aluminum alloys. D0₂₃-Al₃The equilibrium tetragonal structure of the Zr phase has a smaller lattice mismatch with the aluminum matrix, and therefore the thermal stability temperature is higher than that of L1₂-Al₃Zr by conventional cast alloying methodPrepared D0₂₃-Al₃The Zr has a generally thick and long appearance, seriously damages the mechanical property of the alloy, and can prepare equiaxed granular D0 through melt in-situ reaction₂₃-Al₃A Zr phase. However, D0 prepared by melt in situ reaction₂₃-Al₃Few reports of Zr-grain reinforced heat-resistant aluminum alloys, D0₂₃-Al₃The research on the high-temperature performance of the Zr reinforced Al-Cu alloy is not reported yet.

Disclosure of Invention

Aiming at the technical problems, the invention provides a heat-resistant aluminum-based composite material and a preparation method thereof, which meet the use requirements of the fields of ships, weapons, spaceflight, automobiles and the like on high-temperature-resistant aluminum alloy materials.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

a heat-resistant aluminum-based composite material comprises the following elements in percentage by mass: al (Al)₃7-11% of Zr, 4-8% of Cu, 1-3% of Ni, 0.3-0.7% of V and the balance of Al.

Preferably, the elements are respectively as follows by mass percent: al (Al)₃9% of Zr, 6% of Cu, 2% of Ni, 0.5% of V and the balance of Al.

The method for preparing the heat-resistant aluminum-based composite material comprises the following steps:

step S1, weighing the raw materials according to the element proportion; wherein Cu is Al-50Cu intermediate alloy, Ni is Al-10Ni intermediate alloy, V is Al-10V alloy, and Zr is K₂ZrF₆The rest Al adopts pure aluminum blocks;

step S2, heating the pure aluminum block to be molten, adding a covering agent on the surface of the melt, heating to 760-780 ℃, preserving heat for 5-6 min, and slagging off;

step S3, keeping the temperature at 760-780 ℃, adding an Al-50Cu intermediate alloy, an Al-10Ni intermediate alloy and an Al-10V intermediate alloy to the middle lower part of the melt, adding a covering agent on the surface of the melt, standing for 7-8 min, and slagging off;

step S4, keeping the temperature at 760-780 ℃, stirring the melt, and adding K while stirring₂ZrF₆Metal saltContinuously stirring for 4-5 min, standing for 1-3 min, and slagging off;

step S5, keeping the temperature at 740-750 ℃, pressing a refining agent into the bottom of the melt, continuously stirring for 0.5-1.5 min, standing for 2-3 min, slagging off, casting the liquid metal into a preheated mold, solidifying, cooling and demolding;

and S6, carrying out solid solution treatment on the material obtained in the step S5 at the solid solution temperature of 490-570 ℃ for 1-3 h, then carrying out water quenching at room temperature on the material, carrying out artificial aging treatment on the material at the artificial aging temperature of 165-185 ℃ for 7-9 h, and finally carrying out air cooling to obtain the heat-resistant aluminum-based composite material.

Preferably, the purity of the pure aluminum block in step S1 is 99.7%.

Preferably, the covering agent in step S2 and step S3 is a mixture of KCl and NaCl, and the mass ratio of the KCl to the NaCl is 1: 1; in step S2 and step S3, a covering agent is added to the surface of the melt, so that the covering agent covers the surface of the melt, and the thickness of the covering agent is 1 mm.

Preferably, an Al-50Cu master alloy, an Al-10Ni master alloy, and an Al-10V master alloy are sequentially added to the middle-lower portion of the melt in step S3.

Preferably, K in step S4₂ZrF₆The metal salt is in powder form.

Preferably, K is added₂ZrF₆The method of the metal salt comprises the following steps: stirring the melt at 600r/min to generate vortex for the liquid metal, and spraying powder K with a powder sprayer₂ZrF₆The metal salt is slowly sprayed into the vortex generated by stirring to be involved in the melt.

Preferably, the refining agent in the step S5 is hexachloroethane, the addition amount of the refining agent is 1% of the total mass of the melt, the refining agent is added and then stirred for 1min at the rotating speed of 150r/min, and the preheating temperature of the die is 200 ℃;

preferably, the solid solution temperature in the step S6 is 550 ℃, the solid solution time is 2h, the water temperature of room temperature water quenching is 25 ℃, the artificial aging temperature is 175 ℃, and the artificial aging time is 8 h.

Al in the heat-resistant aluminum-based composite material of the invention₃Zr phase is formed by adding K₂ZrF₆The Al-6Cu-2Ni-0.5V alloy melt is generated by in-situ reaction, and the chemical equation of the reaction is as follows: 3K₂ZrF₆+13Al→3Al₃Zr+4AlF₃+6KF, AlF as a by-product of the reaction₃And KF floats slightly above the melt in density and is removed by skimming.

The heat-resistant aluminum-based composite material disclosed by the invention has the advantages that the high-temperature strengthening performance is improved through six aspects:

(1) addition of K to the melt₂ZrF₆Metal salt, high-strength and high-thermal stability strengthening phase D0 introduced by in-situ reaction₂₃-Al₃Zr, the strengthening phase has good thermal stability at 350 ℃, plays a role in precipitation strengthening on the aluminum alloy, hinders dislocation movement of the matrix alloy and improves high-temperature mechanical properties; with Al-containing formed by adding Al-Zr master alloy₃Compared with the Zr-phase aluminum alloy, the composite material prepared by the in-situ reaction has the following advantages: in situ formed D0₂₃-Al₃The Zr strengthening phase has equiaxed granular morphology, and the Zr is alloyed to generate coarse and long Al₃Zr phase, equiaxed fine D0₂₃-Al₃The Zr particles are thermodynamically stable in the matrix, so that the performance of the composite material is reduced less at high temperature; the mechanical property of the alloy at room temperature is also enhanced well; the interface bonding between the strengthening phase and the matrix is good; in situ formed strengthening phase D0₂₃-Al₃The Zr particle size can be controlled, the distribution in the matrix is more uniform, and the mechanical property is better;

(2) after solution heat treatment, there is a fraction D0₂₃-Al₃Conversion of Zr reinforcing phase particles into oval or spherical L1₂-Al_2.5Cu_0.5Zr, which is also a high strength and high hardness phase, has a ratio of D0₂₃-Al₃The Zr phase has higher thermal stability, and the shape is elliptical or spherical, so that the stress concentration of an interface can be reduced, and the high-temperature strengthening effect is further improved;

(3) having theta' -Al in the alloy material of the invention₂A Cu phase at which high-temperature solution heat is performedWhen taking care, there is a trace amount of Al₃The Zr phase is dissolved, a small amount of Zr atoms are dissolved into the matrix, some Zr atoms with low thermal diffusion coefficient are left in the matrix after water quenching, and the Zr atoms can be used as theta' -Al during artificial aging heat treatment₂Heterogeneous nucleating agents for Cu phase, promoting theta' -Al₂The precipitation quantity and size of the Cu phase are increased, and a good high-temperature strengthening matrix effect is achieved;

(4) in theta' -Al₂The interface of the Cu phase and the enrichment of Zr atoms appear in the Cu phase, on one hand, the segregation of the Zr atoms on the interface reduces the interface energy, improves the thermal stability of the Cu phase and better plays a role in high-temperature strengthening, and on the other hand, the Zr atoms with high melting point are in theta' -Al₂The Cu phase plays a role in solid solution strengthening, so that the strength and the thermal stability of the Cu phase are further improved, and the high-temperature strengthening effect is effectively exerted;

(5) the alloy material of the present invention also contains Al₃The CuNi phase is also a high-temperature strengthening phase, and although the three-dimensional network skeleton structure of the CuNi phase is partially dissolved, spheroidized and coarsened after solution heat treatment, the high-temperature strengthening effect is weakened, but still has a certain strengthening effect;

(6) the alloy material of the invention is also added with V element, after the V element is added, all strengthening phases obtain V solid solution strengthening, and the strengthening effect of strengthening the relative matrix is improved.

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

the heat-resistant aluminum-based composite material provided by the invention has very good high-temperature strengthening performance, has better tensile strength at the high temperature of 350 ℃ compared with the existing heat-resistant aluminum alloy material, and is very suitable for the fields of ships, weapons, aviation, aerospace, automobiles and the like. The preparation method of the heat-resistant aluminum-based composite material is simple in process, short in preparation process time and reliable in process, greatly saves production cost, and is easy for large-scale industrial production.

Drawings

FIG. 1 is theta' -Al according to examples 1 and 10 of the present invention₂And (4) Cu phase precipitation.

FIG. 2 is a change of microstructure under a high temperature condition (350 ℃ C.) according to examples 1 and 10 of the present invention.

FIG. 3 shows the microstructure of examples 7 to 12 according to the present invention after treatment at different solution temperatures.

FIG. 4 shows the microstructure of the steel sheet after treatment at different solution temperatures according to examples 1 to 6 of the present invention.

Fig. 5 is a tensile stress-strain curve according to examples 1 to 12 of the present invention.

FIG. 6 shows the precipitation of Al-5Cu-0.2Zr-0.1Ti-0.2V alloy after 5h and 20h aging at 500 deg.C in the prior art.

Detailed Description

The following detailed description is to be read in connection with the accompanying drawings, but it is to be understood that the scope of the invention is not limited to the specific embodiments. The raw materials and reagents used in the examples were all commercially available unless otherwise specified.

Example 1 preparation of a Heat-resistant aluminum-based composite Material

The heat-resistant aluminum-based composite material comprises the following elements in percentage by mass: al (Al)₃9% of Zr, 6% of Cu, 2% of Ni, 0.5% of V and the balance of Al.

Step S1, weighing the raw materials according to the element proportion; wherein Cu is Al-50Cu intermediate alloy, Ni is Al-10Ni intermediate alloy, V is Al-10V alloy, and Zr is K₂ZrF₆The rest Al adopts a pure aluminum block with the purity of 99.7 percent;

step S2, heating the pure aluminum block to be molten, covering a layer of covering agent (a mixture of NaCl and KCl with the mass ratio of 1: 1) with the thickness of 1mm on the surface of the melt, heating to 770 ℃, preserving heat for 5min, and slagging off;

step S3, keeping the temperature at 770 ℃, sequentially adding Al-50Cu intermediate alloy, Al-10Ni intermediate alloy and Al-10V intermediate alloy to the middle lower part of the melt, covering a layer of covering agent (a mixture of NaCl and KCl with the mass ratio of 1: 1) with the thickness of 1mm on the surface of the melt, standing for 7min, and slagging off;

step S4, keeping the temperature at 770 ℃, and stirring at 600r/min to produce liquid metalGenerating vortex, and spraying powder K with powder sprayer₂ZrF₆Slowly spraying the metal salt into vortex generated by stirring to roll the metal salt into the melt, continuously stirring for 5min, standing for 2min, and slagging off;

step S5, keeping the temperature at 745 ℃, pressing hexachloroethane refining agent accounting for 1% of the total mass of the melt into the bottom of the melt, continuously stirring for 1min at the stirring speed of 150r/min, standing for 2min, slagging off, casting liquid metal into a die preheated at 200 ℃, solidifying, cooling and demoulding;

and S6, carrying out solid solution treatment on the material obtained in the step S5 at the solid solution temperature of 550 ℃ for 2 hours, then carrying out water quenching at the temperature of 25 ℃, then carrying out artificial aging treatment on the material at the artificial aging temperature of 175 ℃ for 8 hours, and finally carrying out air cooling to obtain the heat-resistant aluminum-based composite material.

Examples 2 to 6 preparation of Heat-resistant aluminum-based composite Material

The heat-resistant aluminum-based composite material was prepared by using the same raw materials and processes as in example 1, but the solution temperature in step S6 was treated as shown in Table 1 to obtain heat-resistant aluminum-based composite materials treated at different solution temperatures.

TABLE 1 solid solution temperature of examples 2-6

Examples	Solid solution temperature of step S6
		Example 2	490℃
Example 3	510℃
		Example 4	530℃
Example 5	560℃
		Example 6	570℃

Examples 7 to 12 preparation of aluminum-based composite Material

Preparing the aluminum-based composite material, wherein the elements in percentage by mass are as follows: cu 6%, Ni 2%, V0.5%, and the balance of Al;

step S1, weighing the raw materials according to the element proportion; wherein, Cu adopts Al-50Cu intermediate alloy, Ni adopts Al-10Ni intermediate alloy, V adopts Al-10V alloy, and the rest Al adopts pure aluminum blocks with the purity of 99.7%;

step S2 to step S3 and step S5 are the same as in example 1, step S4 is omitted, and the solution temperature of step S6 is treated according to table 2 to obtain aluminum matrix composites treated at different solution temperatures;

TABLE 2 solid solution temperatures for examples 7-12

Example 13 addition of Al₃Zr with no addition of Al₃Theta' -Al of Zr aluminum matrix composite₂Deposition of Cu phase

The results of electron microscope observation of the aluminum-based composite materials of examples 1 and 10 are shown in FIG. 1, wherein in FIG. 1, the left figure is the aluminum-based composite material of example 10, and the right figure is the aluminum-based composite material of example 1, and it can be seen from FIG. 1 that K is added₂ZrF₆The base material is made to contain Al₃After Zr, a larger amount of θ' -Al was precipitated from the material of example 1₂Cu phase, and theta' -Al₂The size of the Cu phase is finer.

Example 14 addition of Al₃Zr with no addition of Al₃The microstructure change condition of the Zr aluminum-based composite material under the high temperature condition (350℃)

The aluminum matrix composites of examples 1 and 10 were heated to 350 ℃ and the results of the heat-retention for 8 hours, 12 hours and 24 hours were observed by an electron microscope, and are shown in FIG. 2.

In FIG. 2, (a) examples 10-8 h; (a') examples 10-16 h; (a') examples 10-24 h; (b) examples 1-8 h; (b') examples 1-16 h; (b') examples 1-24 h.

As can be seen in FIG. 2, the theta' -Al in the matrix of the material of example 1 after thermal exposure₂The size of Cu particles is smaller than that of example 10, indicating that Al₃Zr improves theta' -Al₂The coarsening resistance of the Cu phase and its thermal stability at 350 ℃.

In addition, in the present embodiment, the applicant also dealt with θ' -Al₂The Cu phase is subjected to energy spectrum analysis, trace Zr element is detected, and the fact that the Zr element is partially polymerized on theta' -Al is shown₂On the Cu interface, the interface performance is reduced and the theta' -Al is improved₂Thermal stability of Cu.

Example 15 without addition of Al₃Microstructure condition of Zr aluminum-based composite material after treatment at different solid solution temperatures

The results of observing the aluminum-based composite materials of examples 7 to 12 with an electron microscope are shown in FIG. 3.

In FIG. 3, (b), (b') example 7; (c) (c') example 8; (d) (d') example 9; (e) (e') example 10; (f) (f') example 11; (g) (g') example 12; the numerical labels in the figures represent the following: 1-alpha-Al, 2-theta' -Al₂Cu,3-Al₃CuNi,4-Al₇Cu₄Ni,5-Al₁₀V。

Examples 7 to 12 without addition of K₂ZrF₆The alloy structure does not contain Al₃Zr, their combinationsThe gold structure mainly comprises alpha-Al and Al₂Cu、Al₃Ni、Al₇Cu₄Ni、Al₃CuNi and Al₁₀A phase V; as can be seen from FIG. 3, as the solid solution temperature increases, Al-Al₃Reduced CuNi eutectic structure and Al with three-dimensional network structure₃The CuNi size becomes smaller, and Al is shown from the small graphs (f) and (g)₃The CuNi structure has the phenomena of dissolution, crushing and spheroidization, and finally becomes coarse particles, so that the high-temperature strengthening effect is weakened; as can be seen from the high magnification photographs (b '), (c '), (d '), (e '), (f ') and (g '), finely dispersed theta ' -Al is precipitated in the matrix after the heat treatment of step S6₂Cu particles (200-300 nm) in which theta' -Al is present in the matrix as the solid solution temperature increases₂The amount of Cu particles precipitated increases. In addition, coarse Al₁₀V has no obvious change in size after the heat treatment in the step S6, and the main reason why the performance of the matrix alloy is improved under the high-temperature condition is that the theta' -Al₂And (4) precipitation of a Cu phase.

Example 16 addition of Al₃Microstructure condition of Zr aluminum-based composite material after treatment at different solid solution temperatures

The results of observing the aluminum-based composite materials of examples 1 to 6 with an electron microscope are shown in fig. 4.

In fig. 4, (a), (a') example 2; (b) (b') example 3; (c) (c') example 4; (d) (d') example 1; (e) (e') example 5; (f) (f') example 6; the numerical labels in the figures represent the following: 1-alpha-Al, 2-theta' -Al₂Cu,3-Al₃CuNi,4-Al₇Cu₄Ni,5-Al_2.5Cu_0.5Zr,6-Al₃Zr,7-Al₁₀V。

Examples 1 to 6 with K added₂ZrF₆So that the alloy structure contains Al₃Zr. As can be seen from FIG. 4, the Al-based alloy composite material has a partial block shape D0 with the increasing solid solution temperature₂₃-Al₃The profile of the Zr particles becomes a smooth arc, and a part of Cu atoms is dissolved into Al₃In Zr phase, Al converted into elliptical or circular_2.5Cu_0.5Zr phase, oval or round Al_2.5Cu_0.5The Zr particles are insensitive to stress concentration and crack propagation and are beneficial to precipitation strengthening, and the phase has L1₂Face centered cubic crystal structure with greater thermal stability than tetragonal D0₂₃Structural Al₃A Zr phase. Most massive D0₂₃-Al₃The Zr particles maintain the same size as the as-cast composite material after the heat treatment of step S6, and have thermal stability above 500 ℃. In addition, fine and dispersed θ ' -Al can be seen from the high magnification photographs (b '), (c '), (d '), (e '), (f '), (g ')₂The Cu particles are also uniformly distributed in the composite matrix. Illustrating Al₃Zr、Al_2.5Cu_0.5Precipitation strengthening of Zr phase and theta' -Al₂The dispersion strengthening of Cu is the main reason for improving the performance of the aluminum-based composite material

Example 17 addition of Al₃Zr with no addition of Al₃Tensile stress-strain curve of Zr aluminum-based composite material

The aluminum-based composites of examples 1 to 12 were examined for tensile stress-strain curves at room temperature and high temperature (350 ℃), and the results are shown in fig. 5.

In FIG. 5, (a) examples 7-12 (room temperature); (b) examples 7-12(350 ℃); (c) examples 1-6 (room temperature); (d) examples 1-6(350 ℃ C.).

As can be seen from FIG. 5, Al is added₃The tensile stress of the Zr aluminum matrix composite material is improved at room temperature and high temperature, the improvement is more remarkable at high temperature, and the best effect is obtained in example 1 (solid solution temperature 550 ℃).

Example 18 addition of Al₃Zr with no addition of Al₃Tensile Properties of Zr aluminum matrix composite

The tensile property data of the aluminum matrix composites of examples 1 to 12 at room temperature and high temperature (350 ℃) were examined, and the results are shown in tables 3 to 5;

TABLE 3 tensile Properties at room temperature for examples 7-12

TABLE 4 high temperature (350 ℃ C.) tensile Properties of examples 7-12

TABLE 5 tensile Properties at room temperature for examples 1 to 6

TABLE 6 high temperature (350 ℃ C.) tensile Properties of examples 1-6

As can be seen from tables 3 to 6, Al was added₃The tensile properties of the Zr materials of examples 1 to 6 are significantly better than those of the Zr materials without Al₃The tensile properties of Zr examples 7-12, especially in high temperature conditions, are more significant in examples 1-6, wherein the aluminum matrix composite material of example 1 (solid solution temperature 550 ℃) has the best tensile properties.

Example 19

The high temperature tensile strength of the heat resistant aluminum matrix composite of example 1 was compared with other heat resistant aluminum alloys reported at home and abroad, and the results are shown in table 7:

TABLE 7 comparison of the high-temperature tensile strength of the heat-resistant aluminum-based composite material of example 1 with other heat-resistant aluminum alloys reported at home and abroad

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As can be seen from Table 7, the tensile strength of the heat-resistant aluminum-based composite material of example 1 of the present invention at 350 ℃ is significantly higher than that of other heat-resistant aluminum alloy materials reported at home and abroad at present. The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims

1. The heat-resistant aluminum-based composite material is characterized in that the elements are as follows by mass percent: al (Al)₃7-11% of Zr, 4-8% of Cu, 1-3% of Ni, 0.3-0.7% of V and the balance of Al.

2. The heat-resistant aluminum-based composite material according to claim 1, wherein the elements are, in mass percent: al (Al)₃9% of Zr, 6% of Cu, 2% of Ni, 0.5% of V and the balance of Al.

3. A method of making the heat resistant aluminum matrix composite of claim 1, comprising the steps of:

step S4, keeping the temperature at 760-780 ℃, mechanically stirring the melt, and adding K while stirring₂ZrF₆Continuously stirring the metal salt for 4-5 min, standing for 1-3 min, and slagging off;

step S5, reducing the temperature of the melt to 740-750 ℃, pressing the refining agent into the bottom of the melt, stirring for 0.5-1.5 min, standing for 2-3 min, slagging off, casting the liquid metal into a preheated mold, solidifying, cooling and demolding;

4. A method according to claim 3, characterized by: the purity of the pure aluminum block in the step S1 is 99.7%, the covering agent in the steps S2 and S3 is a mixture of KCl and NaCl, and the mass ratio of the KCl to the NaCl is 1: 1; in step S2 and step S3, a covering agent is added to the surface of the melt, so that the covering agent covers the surface of the melt, and the thickness of the covering agent is 1 mm.

5. A method according to claim 3, characterized by: in step S3, Al-50Cu master alloy, Al-10Ni master alloy and Al-10V master alloy are added to the middle lower part of the melt in sequence.

6. A method according to claim 3, characterized by: k in step S4₂ZrF₆The metal salt is in powder form.

7. Method according to claim 3, characterized in that step S4Adding K₂ZrF₆The method of the metal salt comprises the following steps: stirring the melt at 600r/min to generate vortex for the liquid metal, and spraying powder K with a powder sprayer₂ZrF₆The metal salt is slowly sprayed into the vortex generated by stirring to be involved in the melt.

8. The method of claim 3, wherein the refining agent in step S5 is hexachloroethane, the amount of refining agent added is 1% of the melt mass, the refining agent is added and then stirred at 150r/min for 1min, and the preheating temperature of the mold is 200 ℃.

9. A method according to claim 3, characterized by: in the step S6, the solid solution temperature is 550 ℃, the solid solution time is 2h, the water temperature of room temperature water quenching is 25 ℃, the artificial aging temperature is 175 ℃, and the artificial aging time is 8 h.

10. A heat resistant aluminium matrix composite material prepared according to the method of any one of claims 1 to 9.