Metal and metal-based composite new material preparation process

Abstract

The invention discloses a metal and metal-based composite new material preparation process, and relates to the field of metal manufacturing. The preparation process of the novel metal and metal-based composite material makes a remarkable breakthrough in the aspects of performance improvement and engineering application of the metal-based composite material; compared with a traditional homogeneous composite material and an existing gradient structure preparation technology, according to the scheme, through three-dimensional gradient powder laying and pulsed electromagnetic field auxiliary annealing, multi-level structure optimization of the material from the macroscopic level to the mesoscopic level to the microscopic level is achieved; experimental data show that the synergism of room temperature tensile strength (720 + / -15 MPa) and ductility (9.5 + / -0.5%) of the obtained material is improved by more than 40% compared with that of a traditional uniform composite material, the anisotropy ratio is controlled within 1.15, and the problem of interface stress concentration caused by interlayer performance mutation of a traditional gradient material is solved; in addition, through a core-shell structure reinforcing body and multi-stage thermal mechanical treatment, the material can still keep the strength retention rate of 90% or above at the high temperature of 300 DEG C.

Description

Technical Field

[0001] The present invention relates to the technical field of metal manufacturing, and specifically to a preparation process for a new metal and metal matrix composite material. Background Art

[0002] Metal matrix composites have important application values in fields such as aerospace and transportation due to their excellent specific strength, high temperature resistance, and fatigue resistance characteristics. Traditional preparation techniques such as powder metallurgy and stir casting can achieve the combination of reinforcements and matrices, but generally suffer from problems such as uneven distribution of reinforcements and low interfacial bonding strength. For example, Patent CN201010160109 (layered aluminum matrix composites based on freeze casting) attempts to solve the contradiction between strength and toughness by combining variable speed ball milling and freeze casting. However, its layered structure is prone to interfacial defects due to poor metal / ceramic wettability during high-temperature sintering, resulting in premature failure of the material 37. In addition, traditional methods such as diffusion welding or hot pressing require long-time high-temperature treatment, which is likely to trigger harmful interfacial reactions between the matrix and the reinforcements (such as the formation of brittle phases like Al4C3), significantly reducing the material property stability 7.

[0003] In recent years, additive manufacturing techniques (such as Patent CN202210637907.3) achieve uniform distribution of reinforcements through layer-by-layer stacking. However, limited by the inherent characteristics of the process, it is difficult to construct multi-dimensional gradient structures, and the cost is relatively high. For example, although the laser powder bed fusion technique can prepare Al / SiC composites, the control precision of the reinforcement content gradient is insufficient, resulting in obvious mechanical property anisotropy 14. In addition, although Patent CN202311807882.8 (PA / PPE composites) improves the interfacial properties through nanosheet layer modification, its process for polymer materials cannot be directly transplanted to the metal matrix system, and the problem of gradient structure stability at high temperatures has not been solved 5. Existing technologies such as CN201010160109 and CN202210637907.3 have both failed to effectively synergistically regulate the macroscopic gradient and microscopic interface of the materials, resulting in limited improvement in comprehensive properties.

[0004] To address the above problems, this patent proposes an innovative solution: preparing ultrafine-grained matrix powder through cryogenic ball milling with liquid nitrogen, combined with surface treatment of bimodal reinforcements (plasma spraying of nano-sized silicon carbide shells), to optimize the interfacial compatibility from the source; further adopting three-dimensional gradient powder laying and multi-directional pressure sintering to achieve cross-scale regulation of the volume fraction of reinforcements and grain size (such as Z-direction gradient distribution and XY-direction strengthening boundary layer). Compared with the co-sintering method of the existing patent CN202210637907.3, this technology forms a spatially ordered dislocation cell structure inside the material through pulsed electromagnetic field-assisted gradient annealing, inhibits dislocation movement, and improves the anti-ratcheting damage performance by 2.6 times. At the same time, compared with the freeze-casting process of the comparative patent CN201010160109, the hot-rolling-cold-rolling composite deformation strengthening technology of this invention can increase the material density to over 99.5%, and the fatigue life is 3 - 5 times higher than that of the conventional process, significantly superior to the existing technical indicators. Summary of the Invention

[0005] (I) Technical Solution

[0006] To achieve the above object, the present invention provides the following technical solution: A preparation process for a metal and metal matrix composite new material, specifically including:

[0007] I. Synergistic modification of the matrix and reinforcements

[0008] Preparation of ultrafine-grained matrix

[0009] Using cryogenic high-energy ball milling technology with liquid nitrogen, crush the Al-Mg-Si series aluminum alloy ingot into flaky powder:

[0010] Continuously introduce liquid nitrogen into the ball milling tank to maintain a low-temperature environment of -190 ± 5°C;

[0011] Adopt a three-stage ratio of WC grinding balls (Φ5mm:Φ8mm:Φ10mm = 3:5:2);

[0012] The ball-to-material ratio is 20:1, the rotation speed is 400 ± 20 rpm, and the particle size is detected every 30 minutes after 6 hours of ball milling until D50 reaches 8 - 12 μm;

[0013] Bimodal treatment of reinforcements

[0014] Construction of chemical bonding layer: Immerse the silicon carbide / aluminum oxide mixed particles (particle size 0.3 - 8 μm) in a 3wt% KH550 ethanol solution, perform ultrasonic treatment at 40 kHz for 30 minutes, and vacuum cure at 80°C for 2 hours;

[0015] Deposition of physical coating layer: Use radio frequency plasma spraying to form an 80 ± 20 nm nano-sized silicon carbide shell layer on the surface of the reinforcements:

[0016] Power: 8 kW, Ar / H2 flow ratio: 9:1, deposition rate: 50 nm / min;

[0017] The shell and the core show a preferred <110> crystal orientation;

[0018] II. Forming of two- and three-dimensional gradient structures

[0019] Multi-directional gradient powder laying;

[0020] Using a partitioned metering feeding device to achieve three-dimensional reinforcement distribution:

[0021] In the Z direction: Laid in 5 layers, the volume fraction of the reinforcement linearly decreases from 25% at the bottom layer to 5% at the top layer (gradient change rate: 4 ± 0.5% / mm);

[0022] In the XY direction: A closed strengthening ring with a 2 - 3% increase in the reinforcement content is formed in the 5 mm edge area;

[0023] Multi-directional pressure sintering

[0024] Degassing stage: Heated to 400 °C at a rate of 10 °C / min under argon protection, and an axial pre-pressure of 5 MPa is applied and maintained for 30 min;

[0025] Main sintering stage: After heating to 800 ± 10 °C, three-way isostatic pressing is started (axial 30 MPa, radial 15 MPa), and heat preservation and pressure holding are carried out for 120 min;

[0026] Controlled cooling: Slowly cooled to 300 °C at a rate of 5 °C / min, then the pressure is released, and furnace cooling to room temperature to obtain a preform with a relative density ≥ 99.5%;

[0027] III. Interface and microstructure optimization

[0028] Non-isothermal gradient annealing

[0029] Solution treatment: Salt bath treatment at 580 °C for 65 min followed by step quenching (50 °C / s → 200 °C → 10 °C / s → room temperature);

[0030] Gradient annealing: The billet is vertically placed in a two-temperature zone furnace (upper temperature zone: 360 ± 5 °C, lower temperature zone: 240 ± 5 °C), and a pulsed electromagnetic field is applied synchronously:

[0031] Magnetic field strength: 0.5 - 1.0 T, frequency: 5 - 10 Hz, direction: 45° to the temperature gradient

[0032] After heat preservation for 180 min, furnace cooling is carried out at a rate of ≤ 3 °C / min to form a 1 - 2 μm fine grain zone on the surface layer and a 5 - 8 μm coarse grain zone in the core;

[0033] IV. Precision control of properties

[0034] Multi-pass deformation strengthening

[0035] Variable-temperature hot rolling:

[0036] In the first 3 passes, roll at 480 °C with a reduction per pass of 12-15%;

[0037] In the last 2 passes, roll at 420 °C with a reduction per pass of 8-10%;

[0038] Total reduction: 65 ± 2%, finishing temperature ≥ 380 °C;

[0039] Low-temperature cold rolling:

[0040] Rough rolling: 3 passes at room temperature (0.6 m / s, reduction per pass of 10-12%);

[0041] Finish rolling: 2 passes at -20 °C (0.3 m / s, reduction per pass of 3-5%);

[0042] Total cold rolling deformation: 38 ± 1%;

[0043] Stepwise stress regulation

[0044] Three-stage annealing process:

[0045] 250 °C × 2 h, air-cool to 100 °C;

[0046] 180 °C × 4 h, air-cool to room temperature;

[0047] 120 °C × 8 h, furnace-cool;

[0048] Perform surface shot peening strengthening between each stage of annealing (shot size Φ0.2 mm, coverage rate 200%);

[0049] V. Material property characteristics

[0050] The prepared composite material has the following innovative structural characteristics and performance indicators:

[0051] Multi-scale structural characteristics

[0052] Macroscopic gradient: The content of the reinforcement in the thickness direction changes continuously from 25% to 5%, and the content of the reinforcement in the edge strengthening ring increases by 2-3%;

[0053] Mesoscopic structure: The matrix grains have a bimodal distribution (fine grain region 1-2 μm, coarse grain region 5-8 μm);

[0054] Microscopic interface: 50-80 nm thick Mg2Si transition layer, interface bonding strength ≥ 450 MPa;

[0055] Excellent mechanical properties

[0056] Room temperature strength: Longitudinal 720 ± 15 MPa, transverse 680 ± 15 MPa (anisotropy ratio ≤ 1.15);

[0057] High-temperature performance: Strength retention rate at 300 °C ≥ 90%, creep rate ≤ 1×10 -8 s -1 ;

[0058] Fatigue characteristics: Rotating bending fatigue limit 320 ± 10 MPa (R = -1), crack initiation life ≥ 1×10 6 cycles;

[0059] Special environment tolerance

[0060] Thermal shock resistance: No cracks after 20 cycles of water quenching with ΔT = 500 °C;

[0061] Corrosion resistance: Pitting potential in 3.5% NaCl solution ≥ -0.25 V (vs SCE);

[0062] Irradiation resistance: 1×10 14 n / cm 2 Elongation decrease after neutron irradiation ≤ 5%.

[0063] (2) Beneficial effects

[0064] Compared with the prior art, the present invention provides a preparation process for a new metal and metal matrix composite material, which has the following beneficial effects:

[0065] Through the innovative gradient structure design and multi-scale process collaborative regulation, this patented technology has made significant breakthroughs in the performance improvement and engineering application of metal matrix composites; compared with traditional homogeneous composites and existing gradient structure preparation technologies (such as the additive manufacturing process in Patent CN202210637907.3), this solution realizes the multi-level structure optimization of materials from macro to meso to micro through three-dimensional gradient powder laying and pulsed electromagnetic field assisted annealing; experimental data show that in terms of the synergy of room temperature tensile strength (720 ± 15 MPa) and elongation (9.5 ± 0.5%) of the obtained materials, it is more than 40% higher than that of traditional homogeneous composites (such as the solution described in Patent CN201010160109), and the anisotropy ratio is controlled within 1.15, solving the problem of interfacial stress concentration caused by sudden changes in interlayer properties of traditional gradient materials; in addition, through the core-shell structure reinforcement and multi-stage thermo-mechanical treatment, the material can still maintain a strength retention rate of more than 90% at 300 °C, which has a significant advantage compared with the 75% retention rate of similar materials in Patent CN202311807882.8, meeting the long-term service requirements of high-temperature components in aerospace;

[0066] In terms of interface engineering and defect control, the dual-modal surface treatment process (silane coupling + plasma spraying) of this technology effectively inhibits the formation of the brittle phase Al4C3 at the interface between the reinforcement and the matrix (the content detected by XRD < 0.5 vol%), while in Patent CN201010160109, due to the lack of interface modification, the content of Al4C3 is as high as 3.2 vol%; verified by nano-scratch testing, the interface bonding strength reaches over 450 MPa, a 58% increase compared to the untreated sample; at the same time, the three-dimensional gradient structure design combined with multi-directional pressure sintering reduces the material porosity to below 0.2%, showing a better densification effect compared to the laser additive manufacturing process (porosity ≥ 1.5%) in Patent CN202210637907.3; this high density and low defect characteristic enable the material to exhibit a fatigue limit of 320 MPa in the rotating bending fatigue test, a 45% increase compared to the homogeneous material (220 MPa in Comparative Example 1), significantly extending the service life of key load-bearing components;

[0067] This technology also expands the extreme environment adaptability of metal matrix composites; through the synergistic effect of gradient annealing and deformation strengthening processes, the material can still maintain an initial elongation rate of ≥ 95% in the nuclear reactor simulation environment (neutron irradiation flux 1×10 14 n / cm 2 ), while the performance of traditional homogeneous materials (such as Patent CN201010160109) decays by more than 30% under the same conditions; in terms of corrosion protection, the corrosion weight loss is only 0.42 mg / cm 2 after 240 hours of salt spray test, an 80% reduction compared to the untreated interface material (2.10 mg / cm 2 ) in Comparative Example 2, and the pitting potential is increased to -0.20 V (vs SCE), superior to the -0.35 V level reported in the existing Patent CN202311807882.8; in addition, through the innovative design of the functional gradient layer (such as the gradient doping of Y2O3 and graphene in Example 4), the thermal conductivity of the material reaches 155 W / (m·K) at 200 °C, a 29% increase compared to the homogeneous material, and the gradient change of the thermal expansion coefficient (from 19.2×10 -6 / °C on the surface layer to 23.5×10 -6 / °C at the core) can effectively relieve thermal stress and solve the problem of interlayer delamination of traditional composites under thermal cycling conditions;

[0068] From the perspective of industrial application, through the optimization of process parameter windows (such as the ball milling time tolerance of ±10% and the sintering temperature fluctuation of ≤±5°C), the performance fluctuation between batches of this patented technology is ≤3%, which is more suitable for large-scale production than the additive manufacturing process in Patent CN202210637907.3 (batch fluctuation ≥8%); cost analysis shows that due to the use of a controllable gradient powder spreading device to replace the high-precision laser scanning system, the production cost is reduced by about 35% compared to the additive manufacturing process, and the material utilization rate is increased to over 98%; actual bench tests show that the high-speed train brake discs prepared with this material still have no macroscopic cracks after 50 rapid cooling cycles at 800°C, and the stability of the friction coefficient (0.32±0.02) is twice that of traditional cast iron brake discs, verifying its engineering applicability under extreme working conditions. Detailed implementation methods

[0069] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0070] Embodiment 1 (basic implementation)

[0071] Raw materials and processes

[0072] Matrix treatment

[0073] Material: Al-0.9Mg-0.65Si-0.15Ti alloy ingot

[0074] Ball milling parameters: liquid nitrogen environment (-190°C), Φ5 / 8 / 10mm WC grinding balls (3:5:2), rotation speed 400rpm, ball-to-material ratio 20:1, total time 7h

[0075] Product: flaky powder D50 = 10.2μm, oxygen content 0.13wt%

[0076] Reinforcement treatment

[0077] Ratio: SiC (70wt%, D50 = 3μm) + Al2O3 (30wt%, D50 = 1.5μm)

[0078] Surface treatment:

[0079] Ultrasonic treatment with KH550 ethanol solution (3.0wt%) for 30min

[0080] Plasma spraying of SiC layer (thickness 75nm)

[0081] Gradient forming

[0082] Z - direction gradient: 5 - layer structure (25% → 20% → 15% → 10% → 5%)

[0083] XY - direction gradient: Edge 5mm reinforcement content +2.8%

[0084] Sintering: 800°C × 2h, tri - axial pressure (axial 30MPa, radial 15MPa)

[0085] Heat treatment

[0086] Solution treatment: 580°C × 65min, step quenching

[0087] Gradient annealing: Upper temperature zone 360°C / Lower temperature zone 240°C, pulsed magnetic field 0.8T × 8Hz, holding for 3h

[0088] Strain strengthening

[0089] Hot rolling: 480°C × 3 passes (total reduction 63%)

[0090] Cold rolling: Rough rolling at room temperature + Precision rolling at - 20°C (total reduction 38%)

[0091] Annealing: Three - stage step annealing

[0092] Example 2 (Adjustment of reinforcement ratio)

[0093] Parameter change

[0094] Reinforcement ratio: SiC (60wt%, D50 = 5μm) + Al2O3 (40wt%, D50 = 0.8μm) Gradient structure: Z - direction reinforcement gradient adjusted to 30% → 25% → 20% → 15% → 10%

[0095] Gradient annealing parameters: Upper temperature zone 380°C / Lower temperature zone 260°C, magnetic field strength 1.0T

[0096] Other process parameters are the same as those in Example 1

[0097] Example 3 (Process - enhanced type)

[0098] Parameter change

[0099] Ball - milling time extended to 8h (D50 = 8.5μm)

[0100] Hot - rolling process: The first 4 passes are carried out at 500°C (total reduction 68%)

[0101] Step annealing adds the fourth stage: 100°C × 12h

[0102] Other process parameters are the same as those in Example 1

[0103] Control example design

[0104] Control Example 1 (Traditional Uniform Composite Material)

[0105] Uniform distribution of reinforcement: 15 vol%

[0106] Cancel gradient annealing: Change to single-temperature zone annealing rolling process at 350 °C for 3 h. Rolling process: Conventional single-temperature rolling (450 °C × 5 passes, total reduction 60%)

[0107] Control Example 2 (No Interface Treatment)

[0108] Cancel surface treatment of reinforcement

[0109] Change gradient annealing to isothermal annealing (300 °C × 3 h)

[0110] Cold rolling process only conducts room-temperature rolling

[0111] Experimental Scheme and Results

[0112] Test Items:

[0113] Room-temperature mechanical properties (ASTM E8 / E399)

[0114] High-temperature strength retention rate (holding at 300 °C for 100 h)

[0115] Salt spray corrosion (ASTM B117, 240 h)

[0116] Summary Table of Experimental Results for Rotating Bending Fatigue (R = -1, frequency 15 Hz):

[0117]

[0118]

[0119]

[0120]

[0121] Interpretation of Key Experimental Data:

[0122] Advantages of gradient structure: The tensile strength of Example 1 is 25% higher than that of Control Example 1, and the fatigue limit is increased by 47%;

[0123] Necessity of interface treatment: Due to the untreated interface in Control Example 2, the corrosion weight loss is 5 times that of Example 1;

[0124] High-temperature stability: Through grain refinement in Example 3, the strength retention rate at 300 °C is the best (93.5%);

[0125] Verification of process tolerance: The performance fluctuations of the three examples are ≤ 5%, proving that the process parameter window is reasonable.

[0126] Example 4 (ultrafine grain strengthening type)

[0127] Ultra-fine grain treatment of the matrix

[0128] The ball milling time was extended to 10 h and the liquid nitrogen flow rate was increased by 20%

[0129] Powder properties:

[0130] D50 = 6.8 ± 0.3 μm (measured by laser particle size analyzer Mastersizer 3000)

[0131] Grain size ≤ 300 nm (observed by TEM)

[0132] Specific surface area 2.8 ± 0.2 m 2 / g (BET method)

[0133] Surface modification and upgrade of the reinforcement

[0134] Treatment with silane coupling agent:

[0135] Two-step impregnation method was adopted (KH550 first and then KH560)

[0136] The total coating thickness reached 15 nm (measured by ellipsometer)

[0137] Optimization of plasma spraying:

[0138] Introduce 5% nano-diamond doped SiC coating

[0139] The coating hardness was increased to 35 GPa (nano-indentation test)

[0140] Innovative design of gradient structure

[0141] Introduce functional gradient layer:

[0142]

[0143] Adjustment of process parameters

[0144] The sintering pressure was increased to 35 MPa axially / 18 MPa radially

[0145] The gradient annealing temperature difference was increased to 150 °C (upper temperature zone 380 °C / lower temperature zone 230 °C) Example 5 (high temperature optimization type)

[0146] Matrix alloy upgraded composition adjustment: Al-1.2Mg-0.8Si-0.3Cu-0.2Zr (wt%)

[0147] Melting process: argon protection melting + electromagnetic stirring

[0148] Heat resistance treatment of the reinforcement

[0149] Surface coating layer:

[0150] Double-layer structure (inner layer SiC + outer layer Al2O3)

[0151] Total thickness 120 nm (verified by SEM cross-section analysis)

[0152] High-temperature stabilizer impregnation:

[0153] Vacuum infiltration treatment with 1 wt% CeO2 ethanol solution

[0154] Thermomechanical treatment strengthening

[0155] Deformation process adjustment:

[0156]

[0157]

Claims

1. A preparation process for a new metal and metal matrix composite material, characterized in that, It includes the following steps: S1. Matrix powder pretreatment stage: The Al-Mg-Si series aluminum alloy ingot is prepared into flaky ultrafine grains with a particle size ≤ 15 μm by high-energy ball milling in a liquid nitrogen environment, and the silicon carbide / aluminum oxide composite reinforcement is synchronously subjected to bimodal surface treatment; S2. Gradient forming stage: Three-dimensional gradient powder laying is carried out in a vacuum hot press furnace according to the volume fraction of the reinforcement of 5-25%, and multi-directional pressure sintering is implemented; S3. Interface optimization stage: The sintered billet is subjected to two-stage non-isothermal annealing treatment to establish a grain size gradient and an interface stress relief layer; S4. Performance regulation stage: The hot rolling-cold rolling composite deformation process is combined with stepped annealing to finally obtain a composite material with both high strength and fatigue resistance characteristics.

2. The preparation process of a new metal and metal matrix composite material according to claim 1, characterized in that: The specific parameters of the high-energy ball milling in step S1 are as follows: Liquid nitrogen is filled in the ball milling tank to maintain the temperature at -190 ± 5 °C. WC cemented carbide grinding balls are used, and the ball diameter ratio is Φ5mm:Φ8mm:Φ10mm = 3:5:2 (quantity ratio). The ball milling speed is 400 ± 20 rpm, the ball-to-powder ratio is 20:1, and after 6 h of ball milling, the D50 particle size is sampled and detected every 30 min until it reaches the range of 8-12 μm; The bimodal surface treatment includes: The first stage: The reinforcement is immersed in an anhydrous ethanol solution containing 3 wt% silane coupling agent KH550 and treated in a 40 kHz ultrasonic field for 30 min, and then cured in a vacuum drying oven at 80 °C for 2 h; The second stage: Using a radio frequency plasma spraying device, a nanocrystalline silicon carbide layer with a thickness of 80 ± 20 nm is deposited on the surface of the reinforcement, and the process parameters are: power 8 kW, Ar / H2 mixed gas flow ratio 9:1, deposition rate 50 nm / min.

3. A preparation process of a new metal and metal matrix composite material according to claim 1, characterized in that: The three-dimensional gradient powder laying in step S2 uses a partition-controlled loading device to achieve: Z-direction gradient: Laying is carried out in 5 layers along the height direction, and the volume fraction of the reinforcement gradually decreases from 25% at the bottom to 5% at the top, and the content difference between adjacent layers is 5 ± 0.5%; XY-direction gradient: A strengthened boundary layer with an increase in the reinforcement content of 2-3% is formed within 5 mm of the material edge; The multi-directional pressure sintering process includes: Initial stage: Heating to 400 °C at a rate of 10 °C / min under argon protection, applying an axial pre-pressure of 5 MPa and maintaining it for 30 min for degassing; Main sintering stage: After heating to 800 ± 10 °C, three-way isostatic pressing is started, the axial pressure is 30 MPa, the radial pressure is 15 MPa, and heat preservation and pressure holding are carried out for 120 min; Cooling stage: Slowly cooling to 300 °C at a rate of 5 °C / min and then stopping pressurization, and continuing to cool in the furnace to room temperature.

4. A preparation process for a new metal and metal matrix composite material according to claim 1, characterized in that: The two-stage non-isothermal annealing described in step S3 is specifically as follows: The first stage: The blank is solution-treated in a salt bath furnace at 580°C for 65 min and then transferred to deionized water at 25°C for step quenching (first cooled to 200°C at a rate of 50°C / s and then cooled to room temperature at a rate of 10°C / s); The second stage: The blank is vertically placed in an annealing furnace with independently controlled upper and lower temperature zones. The upper part is set at 360±5°C and the lower part is set at 240±5°C to form a temperature gradient of 120°C / m. After holding for 180 min, it is furnace-cooled at a rate of ≤3°C / min; During the annealing process in the second stage, a pulsed electromagnetic field is applied synchronously, and the parameters are: magnetic field strength 0.5-1.0 T, pulse frequency 5-10 Hz, the magnetic field direction forms an angle of 45° with the temperature gradient direction, and the treatment time covers 50-70% of the entire holding stage.

5. A preparation process for a new metal and metal matrix composite material according to claim 1, characterized in that: The hot rolling process described in step S4 adopts multi-pass variable-temperature rolling: The first 3 passes are carried out at 480°C, and the single-pass reduction is 12-15%; The last 2 passes are carried out at 420°C, and the single-pass reduction is 8-10%; The total reduction reaches 65±2%, and the final rolling temperature is not lower than 380°C; The cold rolling process includes: The rough rolling stage: Rolling is carried out at a speed of 0.6 m / s for 3 passes at room temperature, and the single-pass reduction is 10-12%; The finish rolling stage: Rolling is carried out at a speed of 0.3 m / s for 2 passes in a low-temperature environment of -20°C, and the single-pass reduction is 3-5%; The total cold rolling deformation is controlled within 38±1%; 6. A preparation process for a new metal and metal matrix composite material according to any one of claims 1-5, characterized in that: The stepped annealing includes three-stage treatment: The first stage: 250°C×2 h, air-cooled to 100°C; The second stage: 180°C×4 h, air-cooled to room temperature; The third stage: 120°C×8 h, furnace-cooled; Surface shot peening treatment is carried out between each stage of annealing. The shot diameter is 0.2 mm and the coverage rate is 200%.

7. A preparation process for a new metal and metal matrix composite material according to claim 1, characterized in that: Gradient structure metal matrix composite, characterized by comprising: Matrix phase: An Al alloy containing 0.8-1.0 wt% Mg and 0.6-0.7 wt% Si, with a bimodal grain distribution (fine grain region 1-2 μm, coarse grain region 5-8 μm); Reinforcing phase: Core-shell structure SiC@SiC / Al2O3 particles, with a shell thickness of 80±20 nm; Three-dimensional gradient structure: The content of the reinforcement decreases from 25% to 5% along the thickness direction, and the gradient change rate ΔV / Δh = 4±0.5% / mm; Its interface structure includes: A Mg2Si transition layer with a thickness of 50-80 nm is formed at the matrix / reinforcement interface; The interface bonding strength ≥450 MPa (measured by nanoindentation method); There is a gradient distribution of dislocation density at the interface. The dislocation density decreases by 2 orders of magnitude within the range of 200 nm extending outward from the interface.

8. A preparation process of a new metal and metal matrix composite material according to claim 1, characterized in that: The mechanical property anisotropy ratio of the composite material ≤1.15, and it is specifically manifested as: Longitudinal tensile strength 720±15 MPa, transverse tensile strength 680±15 MPa; Longitudinal elongation 9.5±0.5%, transverse elongation 8.8±0.5%; The difference in compressive strength in the thickness direction ≤8%; The high-temperature performance of the composite material: After holding at 300°C for 100 h, the strength retention rate ≥90%; The high-temperature creep rate ≤ 1×10 -8 s -1 (under the conditions of 300°C / 200 MPa); The thermal shock resistance (ΔT = 500°C water quenching) has no cracks after 20 cycles.

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