High-strength high-plasticity high-damping gradient multilayer ZA22 alloy and preparation method thereof

Abstract

The application discloses a high-strength high-plasticity high-damping gradient multilayer ZA22 alloy and a preparation method thereof. The alloy is a five-layer gradient structure composed of a center layer, two intermediate layers symmetrically arranged on two sides of the center layer, and two outer layers symmetrically arranged on the outer sides of the two intermediate layers; all the layers are made of ZA22 alloy; the overall thickness is 1.5-2.5 mm, the center layer is 100-200 microns, the intermediate layer is 250-400 microns, and the outer layer is 450-750 microns. The application realizes the synergistic optimization of strength, plasticity and damping through gradient layer thickness, rolling and optimized aging. The gradient layer thickness makes the elongation rate increase by about 45%, the damping at 40 DEG C and 292 DEG C increase by about 17% and 85% respectively, and the strength decrease by about 16%; after the optimized aging, the yield strength increases by about 6%, the elongation rate increases by about 97%, the damping at 292 DEG C increases by about 218%, and the damping at 40 DEG C remains basically unchanged.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, specifically to a high-strength, high-plasticity, high-damping gradient multilayer ZA22 alloy and its preparation method. Background Technology

[0002] Vibrations and noise generated by high-power equipment during service can accelerate the failure of components and even the entire system, seriously affecting the safety, reliability, and lifespan of equipment, and reducing personnel comfort. Therefore, vibration reduction and noise reduction technologies are receiving increasing attention. Damping materials can efficiently convert mechanical vibration energy into heat dissipation, making them a key functional medium for achieving structural vibration reduction and wave propagation suppression. Developing new high-damping materials has significant practical and engineering value.

[0003] ZA22 alloy (Zn-22wt%Al alloy), due to its unique eutectoid microstructure (alternating distribution of α and η phases), exhibits excellent damping performance by efficiently dissipating mechanical energy through phase interface slip and dislocation motion under vibration excitation, showing great potential in vibration reduction and noise reduction. However, in its original cast state, this alloy has a coarse microstructure and severe compositional segregation, resulting in low strength. Its as-cast tensile strength is only about 120 MPa, and it is prone to intergranular brittle fracture, severely limiting its safe service capability as a structural material under high load conditions. This contradiction of "high damping - low strength" is the core issue for subsequent research and improvement of this alloy.

[0004] Currently, common methods for achieving microstructure refinement and homogenization include large plastic deformation, rapid solidification, inoculant refinement, deformation heat treatment, and mechanical vibration and ultrasonic oscillation. Among these, large plastic deformation rolling theoretically refines microstructure units to submicron or even nanometer scales through intense shear deformation, and can, to some extent, break up segregated structures and promote compositional homogenization, thereby improving material strength. However, the single-layer hot rolling process of pure ZA22 alloy reported by Liu et al. in Materials Letters 406 (2026) 139905 shows that although the plasticity and damping of the alloy are significantly improved after rolling, the strength decreases. This is because single-layer hot rolling lacks interlayer interface confinement dislocations, making it difficult to balance high strength with high plasticity and high damping.

[0005] While inoculant refining methods can refine the microstructure and improve strength, they often suffer from reduced low-temperature damping and lower absolute elongation. For example, Zhang et al. reported a method for refining ZA22 alloy using an Al-10Nb-3Ce-2.5B inoculant in Trans. Nonferrous Met. Soc. China 34(2024)465-479. The CeB6 and NbB2 particles in this inoculant can act as effective heterogeneous nucleation sites for the α phase, refining the α phase size from approximately 100 μm to approximately 16 μm, and significantly improving the tensile strength and high-temperature damping peak of the alloy. However, the absolute elongation of the alloy obtained by this method is still relatively low, and due to the pinning effect of the inoculant particles on the phase interface, the low-temperature damping performance of the alloy below 120℃ is significantly lower than that of the unrefined alloy. Low-temperature damping is a crucial performance indicator for vibration reduction and noise reduction applications.

[0006] To achieve the aforementioned performance, introducing gradient structures into metallic materials through material structure design and large plastic deformation is becoming an emerging research direction. For example, CN107299302B discloses a method for improving the strength and plasticity matching degree of a metal gradient structure, which uses a composite process of surface shot peening and rolling to achieve a synergistic improvement in the strength and plasticity of aluminum alloys. However, this method has complex procedures, high equipment requirements, and the shot peening process is prone to causing surface microstructure damage. Furthermore, the matching accuracy of the two processes is difficult to control stably. Summary of the Invention

[0007] The purpose of this invention is to address the limitations of current technologies by providing a method for preparing a high-strength, high-ductility, and high-damping gradient multilayer ZA22 alloy. This method introduces a large number of interlayer interface-constrained dislocations through stacked hot rolling, and further employs a gradient layer thickness assembly method with a thinner center and symmetrically increasing thicknesses on both sides. This allows the layer thickness gradient to synergistically interact with the uneven strain field during rolling, forming a grain size gradient in one step, thereby improving strength while retaining high ductility and high damping. This invention achieves synergistic optimization of the strength, ductility, and damping of ZA22 alloy, realizing a simultaneous breakthrough in high strength, high ductility, and high damping, and resolving the long-standing contradiction of "high damping - low strength" in ZA22 alloy.

[0008] The technical solution of this invention is: A high-strength, high-plasticity, and high-damping gradient multilayer ZA22 alloy is disclosed. The alloy has a five-layer gradient structure consisting of a central layer, two intermediate layers symmetrically arranged on both sides of the central layer, and two outer layers symmetrically arranged outside the two intermediate layers. The two intermediate layers have the same thickness, and the two outer layers have the same thickness. All layers are made of ZA22 alloy; the overall thickness of the alloy is 1.5 to 2.5 mm, the thickness of the central layer is 100 to 200 μm, the thickness of the intermediate layer is 250 to 400 μm, and the thickness of the outer layer is 450 to 750 μm.

[0009] A method for preparing a high-strength, high-ductility, and high-damping gradient multilayer ZA22 alloy, comprising the following steps: Step 1: Raw material preparation ZA22 alloy ingots were cut into slices by wire cutting to obtain the pre-rolled plates for each layer used in the stacking process. The thickness of each plate is determined by back-calculation based on the target layer thickness and the total rolling reduction (≥83.3%). The thicknesses of the center layer pre-rolling plate, the intermediate layer pre-rolling plate, and the outer layer pre-rolling plate are independently 0.6–1.2 mm, 1.5–2.4 mm, and 2.7–4.5 mm, respectively, and satisfy the condition that the thickness of the center layer < the thickness of the intermediate layer < the thickness of the outer layer; preferably, the thicknesses are 1.2 mm for the center layer, 2.0 mm for the intermediate layer, and 3.0 mm for the outer layer. The second step is pre-treatment before rolling. The pre-rolled plates of each layer are kept at 370-390℃ for 0.5-1.5 h for homogenization treatment, and then air-cooled to room temperature after being removed from the furnace to obtain the plates to be laminated. The third step is surface treatment and blank assembly. The surfaces of the sheets to be laminated are first coarsely ground with an angle grinder and then finely ground with sandpaper to remove oxide scale. They are then rapidly ultrasonically cleaned with anhydrous ethanol and dried. The sheets are stacked according to the target alloy layer sequence (i.e., symmetrically stacked in the order of outer layer, middle layer, center layer, middle layer, outer layer, i.e., "③ / ② / ① / ② / ③", where ① is the center layer, ② is the middle layer, and ③ is the outer layer), forming five layers of blanks with a total thickness of 9–15 mm. Holes are drilled at the four corners of the stacked blanks, and they are secured with rivets and placed in a stainless steel sheath. A vacuum of 1000 elapsed is then applied. -2 The material is sealed below Pa to obtain the encapsulated blank. Step 4, hot rolling composite The clad billet is preheated at 395–405℃ for 0.5–1.5 h, and then hot-rolled for 7–9 passes with a single-pass reduction of 15%–25%, a total reduction of ≥83.3%, and a final rolled thickness of 1.5–2.5 mm. After rolling, it is water-cooled and the cladding is removed to obtain a gradient multilayer ZA22 alloy billet. At this time, under the synergistic effect of the non-uniform shear stress field of rolling and the layer thickness gradient, the material forms a gradient structure along the rolling normal (thickness direction) in which the grain size decreases from the central layer to the outer layer. Optionally, a fifth step is performed: heat treatment. The above alloy billet was solution treated at 370–385°C for 0.8–1.2 h, followed by artificial aging treatment at 100–270°C for 0.8–1.2 h, and then air-cooled to room temperature to obtain the high-strength, high-plasticity, high-damping gradient multilayer ZA22 alloy.

[0010] The essential features of this invention are: Although conventional equal-thickness stacking introduces interlayer interfaces, since each layer has the same thickness, the average reduction rate and shear deformation experienced by each layer during rolling are basically the same, and the grain refinement degree of each layer is similar. It is difficult to form a significant grain size gradient along the thickness direction, resulting in limited strengthening effect and difficulty in synergistically improving plasticity and damping.

[0011] This invention modifies the billet assembly method, employing a gradient layer thickness design with a thinner center and symmetrically increasing outer layers. This allows the thicker outer layer to withstand greater absolute reduction and surface shear deformation during hot rolling, resulting in more complete fragmentation, elongation, and dynamic recrystallization of the α and η phases, leading to significantly refined grains. Meanwhile, the thinner central layer, located in the middle of the stack, experiences less shear deformation and exhibits a lower degree of grain refinement, maintaining a relatively coarse microstructure. Thus, a gradient structure with fine outer grains and coarse central grains is directly formed in a single hot rolling process, eliminating the need for heterogeneous nucleation particles or additional shot peening.

[0012] The synergistic effect of the third step (gradient thickness billet assembly) and the fourth step (large reduction hot rolling, total reduction ≥ 83.3%) is key to forming the aforementioned gradient structure. The thick outer layer, due to its large initial thickness and location on the rolling surface, experiences greater actual strain and shear strain under the same rolling conditions, resulting in more complete dynamic recrystallization and grain refinement. The thin central layer, located in the middle of the stack and with a smaller thickness, experiences less shear strain and a lower degree of grain refinement. Specifically, the ZA22 alloy has a eutectoid structure, consisting of alternating α-phase (aluminum-rich solid solution) and η-phase (zinc-rich phase). During hot rolling, the α / η lamellar structure of the thick outer layer is subjected to intense shearing, resulting in elongation, twisting, and breakage. Under thermal activation, it undergoes dynamic recrystallization, forming fine equiaxed crystals, with the η-phase redistributing along grain boundaries. The thin central layer, due to its relatively smaller deformation, retains more of the original coarse eutectoid lamellar structure, resulting in a higher phase interface density. This results in a gradient structure with fine outer grains and coarse central grains, similar to a "hard on the outside and soft on the inside" composite structure: the fine outer grains provide high strength, while the relatively coarse central grains retain good plasticity and damping; at the same time, the interlayer interfaces can both hinder dislocation movement and improve strength, and dissipate energy through interface slip during vibration and improve damping, thereby significantly improving plasticity and damping without significantly reducing strength, achieving synergistic optimization of the three.

[0013] The beneficial effects of this invention are: (1) This invention, through the innovative thickness gradient design and the synergistic effect of the non-uniform strain field during rolling, simultaneously completes the construction of the gradient structure and the material forming in a single process, successfully overcoming the long-standing technical challenge of the difficulty in synergistically improving the strength, plasticity and damping of ZA22 alloy. Unlike the existing technology of using inoculants to refine ZA22 alloy (such as the Al-10Nb-3Ce-2.5B inoculant reported by Zhang et al., which improves strength and high-temperature damping but damages low-temperature damping and has a low absolute value of elongation), this invention does not require the introduction of heterogeneous nucleating particles. It simply designs the plate thickness as a gradient structure that increases symmetrically from the center layer to both sides, so that it works synergistically with the non-uniform strain field that decreases from the surface to the inside during rolling, directly inducing the gradient refinement of grains along the thickness direction. The operation is simple, the production cycle is short, and the process repeatability and product consistency are significantly improved.

[0014] (2) This invention achieves a simultaneous improvement in the strength, plasticity, and damping of ZA22 alloy through the synergy of gradient layer thickness and aging process. Based on Comparative Example 1 (equal layer thickness, unaged), Example 2 (gradient layer thickness, unaged) shows that the elongation increases from 33% to 48% (an increase of about 45%) while the yield strength decreases by only about 16%, the damping value at 40℃ increases from 0.0462 to 0.0542 (an increase of about 17%), and the damping value at 292℃ increases from 0.2420 to 0.4490 (an increase of about 85%). It achieves a significant improvement in plasticity and damping at a relatively small strength cost, demonstrating the beneficial effects of the gradient layer thickness structure. Based on the gradient layer thickness, Example 5 (aged at 250℃) showed an approximately 26% increase in yield strength, an approximately 35% increase in elongation, an approximately 72% increase in damping at 292℃, and a slight decrease in damping at 40℃ of approximately 14% compared to Example 2. Compared to Comparative Example 1, Example 5 showed an approximately 6% increase in yield strength, an approximately 97% increase in elongation, an approximately 218% increase in damping at 292℃, and essentially no change in damping at 40℃, achieving an optimal balance between strength, plasticity, and damping. These results demonstrate that the present invention overcomes the contradiction of "high damping - low strength" in ZA22 alloy, achieving a synergistic breakthrough in these three properties.

[0015] (3) This invention demonstrates excellent performance designability and process controllability. By simply adjusting the key parameter of aging temperature, the final performance combination of the material can be directionally tailored. From low-temperature aging (Example 3: elongation 122%, damping value 1.5588 at 292℃) to achieve the optimal balance of high strength, high plasticity, and high damping (Example 5: yield strength 249 MPa, elongation 65%, damping value 0.7705 at 292℃), to high-temperature aging (Example 6: yield strength 252 MPa, tensile strength 275 MPa) to obtain the highest strength to meet high load-bearing requirements, the material properties can be flexibly controlled within a wide range, fully demonstrating the technical advantage of using aging temperature as the single control variable. This highly controllable and flexible process characteristic provides a clear technical path for the customized development of materials for specific working conditions, and its industrial application prospects are clear. Attached Figure Description

[0016] Figure 1 A comparison chart of the yield strength, tensile strength and elongation of the samples obtained in each embodiment; Figure 2 A comparison graph showing the damping performance of the samples obtained in each embodiment at different temperatures; Figure 3 This is a comparison of the microstructures of sample #1 obtained in Example 1 and sample #2 obtained in Example 2. Figure 3 Images (a) and (b) show the microstructure of sample #2 (gradient layer thickness) obtained in Example 2. Figure 3 (c) and (d) in the figure represent the microstructure of sample #1 (equal layer thickness) obtained in Example 1; Figure 4 This is a comparison diagram of the average particle size of the α phase between sample #1 obtained in Example 1 and sample #2 obtained in Example 2. Detailed Implementation

[0017] Example 1: (Comparative Example) This embodiment presents a ZA22 alloy layered material prepared using an equal-thickness stacking rolling process, for comparison with the gradient layer thickness scheme of the present invention.

[0018] The first step is to accurately weigh high-purity zinc (purity ≥99.9wt%) and high-purity aluminum (purity ≥99.9wt%) according to the nominal composition ratio of Zn-22wt%Al, and melt, stir and cast them into ingots at 700℃.

[0019] The second step is to cut the obtained ingot into five plates with dimensions of 50mm×80mm×2.4mm, keep them at 380℃ for 1 hour for homogenization, and then remove them from the furnace and air cool them.

[0020] The third step involves using an angle grinder and sandpaper to polish the alloy surface until it is uniformly rough. Then, it is quickly ultrasonically cleaned with anhydrous ethanol and dried. Five sheets of equal thickness (2.4mm) are stacked, with a total thickness of 12mm. Holes are drilled at the four corners of the stack and secured with rivets. The stack is then placed in a stainless steel sleeve and vacuumed to 100°C. -2 Below Pa and sealed.

[0021] The fourth step involves preheating the cladding billet at 400℃ for 1 hour, followed by 8 passes of hot rolling. The reduction per pass is approximately 20%, the total reduction is ≥83.3%, and the final rolled thickness is approximately 2 mm. After rolling, the billet is water-cooled and the cladding is removed to obtain a multilayer ZA22 alloy material with equal thickness, designated as sample #1.

[0022] This embodiment did not undergo solution aging treatment.

[0023] The test results showed that sample #1 had a yield strength of 235 MPa, a tensile strength of 285 MPa, and an elongation of 33%. At a test frequency of 0.5 Hz, the damping value at 40℃ was 0.0462, and at 292℃, it was 0.2420. Mechanical properties were determined using an electronic universal testing machine at a constant tensile rate of 1 mm / min at room temperature. Damping properties were determined using a dynamic thermomechanical analyzer via the single cantilever method.

[0024] Example 2: The gradient multilayer ZA22 alloy material prepared in this embodiment is formed by stacking and rolling five layers of plates with thicknesses of 3mm, 2mm, 1.2mm, 2mm, and 3mm respectively, and is designated as sample #2. The preparation steps are the same as in Example 1, except for the following two points: In the second step, the wire-cut dimensions of the sheet metal are 50mm×80mm×1.2mm, 50mm×80mm×2mm and 50mm×80mm×3mm respectively; In the third step, the five layers of billets are symmetrically stacked in the order of "3mm / 2mm / 1.2mm / 2mm / 3mm", with a total thickness of 11.2mm. In the fourth step, the final thickness of the hot-rolled billet is approximately 1.74mm. The measured thicknesses of each layer after rolling, from top to bottom, are: outer layer 459 μm, middle layer 309 μm, center layer 191 μm, middle layer 300 μm, and outer layer 484 μm. Thickness measurements were taken along the thickness direction on scanning electron microscope micrographs using ImageJ software. The two outer layers have thicknesses of 459 μm and 484 μm, respectively, and the two intermediate layers have thicknesses of 309 μm and 300 μm, respectively, with a difference of less than 10%, which is within the rolling and measurement error range and meets the symmetrical design requirements. The center layer thickness of 191 μm falls within the 100–200 μm range, the intermediate layer thicknesses all fall within the 250–400 μm range, and the outer layer thicknesses all fall within the 450–750 μm range, consistent with the product structure specifications. The total reduction in this embodiment is approximately 84.5%, meeting the requirement of ≥83.3%.

[0025] This embodiment did not undergo solution aging treatment.

[0026] In this embodiment, the mechanical property testing was conducted according to GB / T 228.1-2021 "Metallic materials, tensile testing—Part 1: Test at room temperature," using an electronic universal testing machine at a constant tensile rate of 1 mm / min at room temperature. Damping performance testing was performed using a dynamic thermomechanical analyzer (DMA) with a single cantilever method, a testing frequency of 0.5 Hz, a heating rate of 5 ℃ / min, and a sample size of 35 mm × 10 mm × 2 mm (length × width × thickness). The test results showed that sample #2 had a yield strength of 198 MPa, a tensile strength of 234 MPa, and an elongation of 48%; the damping value at 40℃ was 0.0542, and the damping value at 292℃ was 0.4490. Compared to Example 1, the yield strength decreased by only about 16%, while the elongation, damping at 40℃, and damping at 292℃ increased by approximately 45%, 17%, and 85%, respectively. This represents a significant improvement in plasticity and damping at a relatively small strength cost, achieving synergistic performance optimization. The testing conditions for the remaining embodiments were the same.

[0027] Figure 3 and Figure 4 A comparison of the microstructures of the gradient layer thickness sample (2#) and the equal layer thickness sample (1#) is presented. Figure 3 Images (a) and (b) show the microstructure of samples with gradient layer thickness, where 1 corresponds to the central layer, 2 and 3 correspond to the two intermediate layers respectively, and 4 corresponds to the outer layer; images (c) and (d) show the microstructure of samples with equal layer thickness. Figure 3It is evident that in gradient-thickness samples, the amount of coarse α-phase (black phase) gradually decreases from the central layer to the outer layer, with almost no coarse α-phase observed in the outer region, while fine equiaxed α-phase dominates; whereas in samples of uniform thickness, the amount of coarse α-phase shows no significant difference along the thickness direction. Figure 4 It can be seen that the average particle size of the α phase in samples with equal layer thickness is basically consistent along the thickness direction; while in samples with gradient layer thickness, the α phase particles in the outer layer are significantly finer, while the α phase particles in the central layer are relatively coarser, forming a gradient structure in which the grain size increases from the outer layer to the center along the thickness direction. The reason for the above difference is that the thick outer layer is subjected to greater absolute reduction and shear deformation during hot rolling, and the α and η phases are fully broken, elongated, and dynamically recrystallized to form fine equiaxed crystals; while the thin central layer is located in the middle of the stack, with less deformation, and retains more of the original coarse eutectoid lamellar structure. This gradient structure enables the material to provide higher strength in the fine outer grains under stress, while the coarse central grains dissipate energy through phase interface slip and dislocation movement, thereby achieving a synergistic improvement in strength, plasticity, and damping.

[0028] To facilitate understanding of the contributions of each process factor, the following explanation is provided: Examples 2 and 1 are both in a non-heat-treated state, and the comparison between the two reflects the effect of the gradient layer thickness structure alone; Examples 3 to 6 are all based on Example 2 with further aging, and the comparison between them and Example 2 reflects the control effect of aging temperature on the basis of gradient structure; the comparison between Examples 3 to 6 and Example 1 reflects the combined effect of gradient layer thickness and aging, and is not used for single variable attribution.

[0029] Example 3: This embodiment, based on Embodiment 2, adds solution treatment and artificial aging treatment: the rolled alloy billet is subjected to solution treatment (380℃ / 1h) and artificial aging treatment (150℃ / 1h), and then air-cooled to room temperature, designated as sample #3. The remaining steps are the same as in Embodiment 2.

[0030] Tests showed that sample #3 had a yield strength of 202 MPa, a tensile strength of 211 MPa, and an elongation of 122%; its damping value at 40℃ was 0.0556, and its damping value at 292℃ was 1.5588. Compared with Example 1, the damping at 292℃ and elongation increased by 6.44 times and 3.70 times, respectively; compared with Example 2, the damping at 292℃ and elongation increased by 3.47 times and 2.54 times, respectively, achieving a breakthrough increase in damping and plasticity while maintaining strength.

[0031] Example 4: Based on Example 2, this embodiment adjusts the artificial aging temperature to 200℃ (solution treatment at 380℃ / 1h remains unchanged), followed by air cooling, and is designated as sample #4.

[0032] Tests showed that sample #4 had a yield strength of 221 MPa, a tensile strength of 237 MPa, and an elongation of 102%; its damping value at 40℃ was 0.0521, and its damping value at 292℃ was 1.1360. Compared with Example 1, the damping at 40℃ increased by approximately 13%, and the damping and elongation at 292℃ increased by 4.69 times and 3.09 times, respectively; compared with Example 2, the damping and elongation at 292℃ increased by 2.53 times and 2.13 times, respectively, maintaining excellent damping and plasticity while showing a slight increase in strength.

[0033] Example 5: Based on Example 2, this embodiment adjusts the artificial aging temperature to 250℃ (solution treatment temperature of 380℃ / 1h remains unchanged), followed by air cooling, and is recorded as sample #5.

[0034] Tests showed that sample #5 had a yield strength of 249 MPa, a tensile strength of 269 MPa, and an elongation of 65%; the damping value at 40℃ was 0.0467, and the damping value at 292℃ was 0.7705. Compared with Example 1, the damping and elongation at 292℃ increased by 3.18 times and 1.97 times, respectively; compared with Example 2, the damping at 292℃ increased by approximately 72%, the yield strength increased by approximately 26%, and the elongation increased by approximately 35%. Although the damping at 40℃ was slightly lower than that in Example 2 (0.0467 vs 0.0542), it was still within the high damping range, and the material achieved an optimal balance between strength, plasticity, and damping under this aging condition.

[0035] Example 6: Based on Example 2, this embodiment adjusts the artificial aging temperature to 260℃ (solution treatment temperature of 380℃ / 1h remains unchanged), followed by air cooling, and is recorded as sample #6.

[0036] Tests showed that sample #6 had a yield strength of 252 MPa, a tensile strength of 275 MPa, and an elongation of 19%; its damping value at 40℃ was 0.0432, and its damping value at 292℃ was 0.6768. Compared to Example 2, the yield strength increased by approximately 27%, reaching the highest value among all examples. Although the damping at 40℃ decreased to 0.0432, it still met the application requirements for high-damping materials and maintained a certain degree of plasticity.

[0037] In the above embodiments, the test results of the mechanical properties and damping properties of the samples obtained in each embodiment are summarized in Figure 1 and Figure 2 The raw materials and equipment involved are all known in the art or can be obtained commercially, and the operating methods involved are mastered by those skilled in the art.

[0038] For ease of comparison, the main performance parameters of the ZA22 alloys obtained in each embodiment are summarized in Table 1. As shown in Table 1, compared with the comparative example (Example 1, equal layer thickness), Example 2, by introducing a gradient layer thickness design, significantly improved elongation and damping performance while only decreasing the yield strength by about 16%. Examples 3-6 further demonstrate that by simply changing the aging temperature, the directional control of material strength and plasticity can be achieved while maintaining high damping, reflecting good performance designability.

[0039] Table 1. Main performance parameters of ZA22 alloys obtained in each embodiment

[0040] Matters not covered in this invention are common knowledge.

Claims

1. A high-strength, high-ductility, high-damping gradient multilayer ZA22 alloy, characterized in that, The alloy has a five-layer gradient structure consisting of a central layer, two intermediate layers symmetrically arranged on both sides of the central layer, and two outer layers symmetrically arranged outside the two intermediate layers; the two intermediate layers have the same thickness, and the two outer layers have the same thickness. All layers are made of ZA22 alloy; the overall thickness of the alloy is 1.5 to 2.5 mm, the thickness of the central layer is 100 to 200 μm, the thickness of the intermediate layer is 250 to 400 μm, and the thickness of the outer layer is 450 to 750 μm.

2. A method for preparing a high-strength, high-ductility, high-damping gradient multilayer ZA22 alloy, characterized in that, The method includes the following steps: Step 1: Raw material preparation ZA22 alloy ingots were cut into slices by wire cutting to obtain the pre-rolled plates for each layer used in the stacking process. The thicknesses of the center layer pre-rolled plate, the intermediate layer pre-rolled plate, and the outer layer pre-rolled plate are 0.6–1.2 mm, 1.5–2.4 mm, and 2.7–4.5 mm, respectively, and satisfy the condition that the thickness of the center layer is less than the thickness of the intermediate layer and the thickness of the outer layer. The second step is pre-treatment before rolling. The pre-rolled plates of each layer are kept at 370-390℃ for 0.5-1.5 h for homogenization treatment, and then air-cooled to room temperature after being removed from the furnace to obtain the plates to be laminated. The third step is surface treatment and blank assembly. The surfaces of the sheets to be laminated are first coarsely ground with an angle grinder and then finely ground with sandpaper to remove oxide scale. They are then rapidly ultrasonically cleaned with anhydrous ethanol and dried. The sheets are symmetrically stacked in the order of outer layer, middle layer, center layer, middle layer, and outer layer to form five layers of blank, with a total thickness of 9–15 mm. Holes are drilled at the four corners of the stacked blanks, and they are secured with rivets before being placed in a stainless steel sleeve and vacuumed to 100°C. -2 The material is sealed below Pa to obtain the cladding blank; Step 4, hot rolling composite The clad billet is preheated at 395–405℃ for 0.5–1.5 h, then hot rolled in 7–9 passes with a single pass reduction of 15%–25%, a total reduction of ≥83.3%, and a final rolled thickness of 1.5–2.5 mm. After rolling, it is water-cooled and the cladding is removed to obtain the gradient multilayer ZA22 alloy billet.

3. The preparation method according to claim 2, characterized in that, The thickness of the center layer pre-rolled plate is 1.2 mm, the thickness of the middle layer pre-rolled plate is 2.0 mm, and the thickness of the outer layer pre-rolled plate is 3.0 mm.

4. The preparation method according to claim 2, characterized in that, The process also includes a fifth step: heat treatment, in which the alloy billet is solution treated at 370–385°C for 0.8–1.2 h, followed by artificial aging treatment at 100–270°C for 0.8–1.2 h, and then air-cooled to room temperature to obtain the high-strength, high-plasticity, high-damping gradient multilayer ZA22 alloy.

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