A method for physical vapor deposition-assisted laser shock strengthening of titanium alloy

Abstract

The invention discloses a method for physical vapor deposition-assisted laser shock strengthening of a titanium alloy. The method comprises: depositing a first NiZn layer on the surface of the titanium alloy by magnetron sputtering; depositing a first NiAl layer on the surface of the first NiZn layer by magnetron sputtering; depositing a second NiZn layer on the surface of the first NiAl layer by magnetron sputtering; depositing a second NiAl layer on the surface of the second NiZn layer by magnetron sputtering to obtain a coated titanium alloy to be strengthened; and performing laser shock fatigue strengthening on the coated titanium alloy to be strengthened; wherein the Ni contents in the first NiZn layer and the second NiZn layer are different, and the Ni contents in the first NiAl layer and the second NiAl layer are different, wherein the thickness of the first NiAl layer is at least 100 nm greater than the thickness of the first NiZn layer, the thickness of the second NiZn layer is at least 100 nm greater than the thickness of the first NiAl layer, and the thickness of the second NiAl layer is at least 100 nm greater than the thickness of the second NiZn layer.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and in particular to a method for physical vapor deposition-assisted laser shock strengthening of titanium alloy. Background Art

[0002] Laser shock peening technology is a common way of material enhancement. Prior art CN116555709A discloses a method and application of physical vapor deposition assisted laser shock fatigue strengthening, the main technical solution of which is to plate a metal film on the substrate to be strengthened, thereby ensuring that during the laser shock fatigue strengthening process, cracks will not first develop towards the substrate. This prior art puts forward two main viewpoints: 1. The metal film needs to make the cracks generated first expand along the interface between the metal film and the substrate rather than expand into the interior of the substrate; 2. The bonding force between the metal film and the surface of the substrate needs to be lower than the atomic bonding force of the substrate itself, to ensure that a weak bond is formed between the metal and the substrate, rather than a strong bond, so as to facilitate the subsequent steps of removing the metal film from the surface of the substrate. The inventors have found that through further design of the metal film layer, it is possible to better ensure that the cracks expand along the interface between the metal film and the substrate, rather than expanding into the interior of the substrate, while ensuring that only a weak bond is always generated between the metal film and the substrate. Summary of the Invention

[0003] To achieve the above object, the present invention provides a method for physical vapor deposition-assisted laser shock strengthening of titanium alloy, characterized in that the method comprises:

[0004] depositing a first NiZn layer on the titanium alloy surface by magnetron sputtering;

[0005] depositing a first NiAl layer on the surface of the first NiZn layer by magnetron sputtering;

[0006] depositing a second NiZn layer on the surface of the first NiAl layer by magnetron sputtering;

[0007] depositing a second NiAl layer on the surface of the second NiZn layer by magnetron sputtering to obtain a coated titanium alloy to be strengthened;

[0008] Laser shock fatigue strengthening is performed on the coated titanium alloy to be strengthened;

[0009] The Ni content in the first NiZn layer and the second NiZn layer is different, and the Ni content in the first NiAl layer and the second NiAl layer is different. The thickness of the first NiAl layer is at least 100 nm greater than the thickness of the first NiZn layer, the thickness of the second NiZn layer is at least 100 nm greater than the thickness of the first NiAl layer, and the thickness of the second NiAl layer is at least 100 nm greater than the thickness of the second NiZn layer.

[0010] In a preferred embodiment, the chemical formula of the first NiZn layer is Ni3Zn5, and the chemical formula of the second NiZn layer is Ni3Zn4.

[0011] In a preferred embodiment, the chemical formula of the first NiAl layer is Ni2Al7, and the chemical formula of the second NiAl layer is Ni2Al5.

[0012] In a preferred embodiment, the thickness of the first NiZn layer is 50-100 nm, the thickness of the first NiAl layer is 200-300 nm, the thickness of the second NiZn layer is 400-500 nm, and the thickness of the second NiAl layer is 600-700 nm.

[0013] In a preferred embodiment, the specific process of depositing the first NiZn layer on the titanium alloy surface by magnetron sputtering is as follows:

[0014] The sputtering target is Ni3Zn5 target, the sputtering power supply is a radio frequency power supply, the sputtering voltage is 50-60V, the sputtering power is 40-50W, the sputtering temperature is 100-150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30-40sccm.

[0015] In a preferred embodiment, the specific process of depositing the first NiAl layer on the surface of the first NiZn layer by magnetron sputtering is as follows:

[0016] The sputtering target is Ni2Al7 target, the sputtering power supply is a radio frequency power supply, the sputtering voltage is 70-80V, the sputtering power is 40-50W, the sputtering temperature is 100-150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30-40sccm.

[0017] In a preferred embodiment, the specific process of depositing the second NiZn layer on the surface of the first NiAl layer by magnetron sputtering is as follows:

[0018] The sputtering target is Ni3Zn4 target, the sputtering power supply is a radio frequency power supply, the sputtering voltage is 50-60V, the sputtering power is 70-80W, the sputtering temperature is 100-150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30-40sccm.

[0019] In a preferred embodiment, the specific process of depositing the second NiAl layer on the surface of the second NiZn layer by magnetron sputtering is as follows:

[0020] The sputtering target is Ni2Al5 target, the sputtering power supply is a radio frequency power supply, the sputtering voltage is 50-60V, the sputtering power is 70-80W, the sputtering temperature is 100-150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30-40sccm.

[0021] The present invention provides a titanium alloy subjected to laser shock fatigue strengthening. The titanium alloy is prepared by the above-mentioned method.

[0022] Compared with the existing technology, the present invention has the following advantages: the existing technology uses a single metal film structure to protect the titanium alloy. At the beginning of the laser strengthening process, the direction of least crack propagation resistance is at the interface between the titanium alloy and the metal film, so the crack may propagate at the interface of the titanium alloy and the metal film. However, after the crack expands to a certain extent, the direction of least crack propagation resistance may be toward the titanium alloy substrate, at which point the crack will propagate toward the titanium alloy substrate. The present invention uses a composite alloy film. The composite alloy film proposed in the present invention can maximize the crack propagation away from the titanium alloy substrate during the laser strengthening process, thereby improving the performance of the strengthened titanium alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a method flow chart of an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of the structure of a coated titanium alloy to be strengthened according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0026] Figure 1 1 is a flow chart of a method according to an embodiment of the present invention. As shown in the figure, the method according to the present invention includes the following steps:

[0027] Step 1: depositing a first NiZn layer on the titanium alloy surface by magnetron sputtering; those skilled in the art will appreciate that before depositing the first NiZn layer on the titanium alloy surface, the titanium alloy surface may be cleaned using a suitable organic solvent;

[0028] Step 2: depositing a first NiAl layer on the surface of the first NiZn layer by magnetron sputtering;

[0029] Step 3: Depositing a second NiZn layer on the surface of the first NiAl layer by magnetron sputtering;

[0030] Step 4: depositing a second NiAl layer on the surface of the second NiZn layer by magnetron sputtering to obtain a coated titanium alloy to be strengthened;

[0031] Step 5: Laser shock fatigue strengthening is performed on the coated titanium alloy to be strengthened; the film structure of the coated titanium alloy to be strengthened can be found in Figure 2Those skilled in the art will appreciate that, after laser shock fatigue strengthening of the coated titanium alloy, the composite alloy film coated on the surface of the titanium alloy can be removed by mechanical removal methods such as ultrasonic vibration, tape adhesion, or friction. This method for removing the thin film is described in detail in the prior art CN116555709A and will not be described in detail in the present invention. In the present invention, a pulsed laser strengthening process is used. During the laser shock fatigue strengthening process, the pulse width of the pulsed laser is 7ns. Prior to laser shock fatigue strengthening, the titanium alloy is heated to 400°C. The dimensions of the embodiments and comparative examples of the present invention can be found in CN116555709A.

[0032] The Ni content in the first NiZn layer and the second NiZn layer is different, and the Ni content in the first NiAl layer and the second NiAl layer is different. The thickness of the first NiAl layer is at least 100 nm greater than the thickness of the first NiZn layer, the thickness of the second NiZn layer is at least 100 nm greater than the thickness of the first NiAl layer, and the thickness of the second NiAl layer is at least 100 nm greater than the thickness of the second NiZn layer.

[0033] In a preferred embodiment, the chemical formula of the first NiZn layer is Ni3Zn5, and the chemical formula of the second NiZn layer is Ni3Zn4.

[0034] In a preferred embodiment, the chemical formula of the first NiAl layer is Ni2Al7, and the chemical formula of the second NiAl layer is Ni2Al5.

[0035] In a preferred embodiment, the thickness of the first NiZn layer is 50-100 nm, the thickness of the first NiAl layer is 200-300 nm, the thickness of the second NiZn layer is 400-500 nm, and the thickness of the second NiAl layer is 600-700 nm.

[0036] In a preferred embodiment, the specific process of depositing the first NiZn layer on the titanium alloy surface by magnetron sputtering is as follows:

[0037] The sputtering target is a Ni3Zn5 target, the sputtering power source is an RF power supply, the sputtering voltage is 50-60V, the sputtering power is 40-50W, the sputtering temperature is 100-150°C, and the sputtering atmosphere is an argon atmosphere with an argon flow rate of 30-40sccm. Ni3Zn5 targets can be ordered directly from chemical stores.

[0038] In a preferred embodiment, the specific process of depositing the first NiAl layer on the surface of the first NiZn layer by magnetron sputtering is as follows:

[0039] The sputtering target is Ni2Al7, the sputtering power source is an RF power supply, the sputtering voltage is 70-80V, the sputtering power is 40-50W, the sputtering temperature is 100-150°C, the sputtering atmosphere is argon, and the argon flow rate is 30-40sccm. Ni2Al7 targets can be ordered directly from chemical stores.

[0040] In a preferred embodiment, the specific process of depositing the second NiZn layer on the surface of the first NiAl layer by magnetron sputtering is as follows:

[0041] The sputtering target is a Ni3Zn4 target, the sputtering power source is an RF power supply, the sputtering voltage is 50-60V, the sputtering power is 70-80W, the sputtering temperature is 100-150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30-40sccm. Ni3Zn4 targets can be ordered directly from chemical stores.

[0042] In a preferred embodiment, the specific process of depositing the second NiAl layer on the surface of the second NiZn layer by magnetron sputtering is as follows:

[0043] The sputtering target is Ni2Al5, the sputtering power source is an RF power supply, the sputtering voltage is 50-60V, the sputtering power is 70-80W, the sputtering temperature is 100-150°C, and the sputtering atmosphere is argon with an argon flow rate of 30-40sccm. Ni2Al5 targets can be ordered directly from chemical stores.

[0044] Example 1

[0045] The methods of physical vapor deposition-assisted laser shock strengthening of titanium alloys include:

[0046] depositing a first NiZn layer on the surface of the titanium alloy by magnetron sputtering; depositing a first NiAl layer on the surface of the first NiZn layer by magnetron sputtering; depositing a second NiZn layer on the surface of the first NiAl layer by magnetron sputtering; depositing a second NiAl layer on the surface of the second NiZn layer by magnetron sputtering to obtain a coated titanium alloy to be strengthened; and performing laser shock fatigue strengthening on the coated titanium alloy to be strengthened;

[0047] The chemical formula of the first NiZn layer is Ni3Zn5, and the chemical formula of the second NiZn layer is Ni3Zn4. The chemical formula of the first NiAl layer is Ni2Al7, and the chemical formula of the second NiAl layer is Ni2Al5.

[0048] The thickness of the first NiZn layer is 50 nm, the thickness of the first NiAl layer is 200 nm, the thickness of the second NiZn layer is 400 nm, and the thickness of the second NiAl layer is 600 nm.

[0049] The specific process of depositing the first NiZn layer on the titanium alloy surface by magnetron sputtering is as follows: the sputtering target is Ni3Zn5 target, the sputtering power supply is RF power supply, the sputtering voltage is 50V, the sputtering power is 40W, the sputtering temperature is 100°C, the sputtering atmosphere is argon atmosphere, and the argon flow rate is 30sccm.

[0050] The specific process of depositing the first NiAl layer on the surface of the first NiZn layer by magnetron sputtering is as follows: the sputtering target is Ni2Al7 target, the sputtering power is RF power, the sputtering voltage is 70V, the sputtering power is 40W, the sputtering temperature is 100°C, the sputtering atmosphere is argon atmosphere, and the argon flow rate is 30sccm.

[0051] The specific process of depositing the second NiZn layer on the surface of the first NiAl layer by magnetron sputtering is as follows: the sputtering target is Ni3Zn4 target, the sputtering power is RF power supply, the sputtering voltage is 50V, the sputtering power is 70W, the sputtering temperature is 100℃, the sputtering atmosphere is argon atmosphere, and the argon flow rate is 30sccm.

[0052] The specific process of depositing the second NiAl layer on the surface of the second NiZn layer by magnetron sputtering is as follows: the sputtering target is a Ni2Al5 target, the sputtering power source is a radio frequency power source, the sputtering voltage is 50V, the sputtering power is 70W, the sputtering temperature is 100°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30sccm. The test conditions can refer to CN116555709A. Specifically, the composite alloy layer on the surface of the titanium alloy obtained in Example 1 is first removed, and then the sample of Example 1 is placed on a three-point bending tester, maintaining a maximum pressure of 300Mpa until the sample breaks. The number of cycles of Example 1 is 1203453 times. The reason why the performance of the titanium alloy of the present invention is better than that of CN116555709A is mainly because the titanium alloy of the present invention has fewer cracks on its surface and inside after laser shock strengthening. In the subsequent complete fatigue test, since the titanium alloy itself has fewer cracks, the time of its initial crack appearance is delayed, thereby making the performance of the titanium alloy better than that of CN116555709A. In the present invention, the reason why the titanium alloy has fewer surface and internal cracks after laser shock strengthening is that the crack always propagates in the direction of least resistance, similar to the single metal film structure in CN116555709A. The direction of least resistance to crack propagation is at the interface between the titanium alloy and the metal film, so the crack may propagate at the interface between the titanium alloy and the metal film. However, when the crack propagates to a certain extent, the direction of least resistance to crack propagation may be toward the titanium alloy substrate. At this time, the crack will propagate toward the titanium alloy substrate. In the present invention, the direction of least resistance to crack propagation may also be at the interface between the titanium alloy and the first NiZn layer. As the crack propagates, since the first NiZn layer is also adjacent to the first NiAl layer, there is also an interface between the first NiZn layer and the first NiAl layer. This interface may cause the resistance of the first NiZn layer toward the first NiAl layer to become smaller. In addition, the first NiZn layer itself, as an alloy film, may also have certain defects inside. This also causes the crack to propagate toward the interior of the first NiZn layer instead of toward the titanium alloy substrate. The principles underlying the other film layers are similar to those of the first NiZn layer. However, it should be noted that not all stacked alloy films will guide crack propagation toward the metal film. In other words, the present invention minimizes crack formation in the titanium alloy by directing cracks toward the alloy film, thereby improving performance.

[0053] Example 2

[0054] The methods of physical vapor deposition-assisted laser shock strengthening of titanium alloys include:

[0055] depositing a first NiZn layer on the surface of the titanium alloy by magnetron sputtering; depositing a first NiAl layer on the surface of the first NiZn layer by magnetron sputtering; depositing a second NiZn layer on the surface of the first NiAl layer by magnetron sputtering; depositing a second NiAl layer on the surface of the second NiZn layer by magnetron sputtering to obtain a coated titanium alloy to be strengthened; and performing laser shock fatigue strengthening on the coated titanium alloy to be strengthened;

[0056] The chemical formula of the first NiZn layer is Ni3Zn5, and the chemical formula of the second NiZn layer is Ni3Zn4. The chemical formula of the first NiAl layer is Ni2Al7, and the chemical formula of the second NiAl layer is Ni2Al5.

[0057] The thickness of the first NiZn layer is 100 nm, the thickness of the first NiAl layer is 300 nm, the thickness of the second NiZn layer is 500 nm, and the thickness of the second NiAl layer is 700 nm.

[0058] The specific process of depositing the first NiZn layer on the titanium alloy surface by magnetron sputtering is as follows: the sputtering target is Ni3Zn5 target, the sputtering power supply is RF power supply, the sputtering voltage is 60V, the sputtering power is 50W, the sputtering temperature is 150°C, the sputtering atmosphere is argon atmosphere, and the argon flow rate is 30sccm.

[0059] The specific process of depositing the first NiAl layer on the surface of the first NiZn layer by magnetron sputtering is as follows: the sputtering target is Ni2Al7 target, the sputtering power is RF power, the sputtering voltage is 80V, the sputtering power is 50W, the sputtering temperature is 150°C, the sputtering atmosphere is argon atmosphere, and the argon flow rate is 30sccm.

[0060] The specific process of depositing the second NiZn layer on the surface of the first NiAl layer by magnetron sputtering is as follows: the sputtering target is Ni3Zn4 target, the sputtering power supply is RF power supply, the sputtering voltage is 60V, the sputtering power is 80W, the sputtering temperature is 150℃, the sputtering atmosphere is argon atmosphere, and the argon flow rate is 30sccm.

[0061] The specific process for depositing the second NiAl layer on the surface of the second NiZn layer by magnetron sputtering is as follows: the sputtering target is a Ni2Al5 target, the sputtering power source is an RF power source, the sputtering voltage is 60V, the sputtering power is 80W, the sputtering temperature is 150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30sccm. The number of cycles in Example 2 is 1,246,364.

[0062] Example 3

[0063] The methods of physical vapor deposition-assisted laser shock strengthening of titanium alloys include:

[0064] depositing a first NiZn layer on the surface of the titanium alloy by magnetron sputtering; depositing a first NiAl layer on the surface of the first NiZn layer by magnetron sputtering; depositing a second NiZn layer on the surface of the first NiAl layer by magnetron sputtering; depositing a second NiAl layer on the surface of the second NiZn layer by magnetron sputtering to obtain a coated titanium alloy to be strengthened; and performing laser shock fatigue strengthening on the coated titanium alloy to be strengthened;

[0065] The chemical formula of the first NiZn layer is Ni3Zn5, and the chemical formula of the second NiZn layer is Ni3Zn4. The chemical formula of the first NiAl layer is Ni2Al7, and the chemical formula of the second NiAl layer is Ni2Al5.

[0066] The thickness of the first NiZn layer is 70 nm, the thickness of the first NiAl layer is 250 nm, the thickness of the second NiZn layer is 450 nm, and the thickness of the second NiAl layer is 650 nm.

[0067] The specific process of depositing the first NiZn layer on the titanium alloy surface by magnetron sputtering is as follows: the sputtering target is Ni3Zn5 target, the sputtering power supply is RF power supply, the sputtering voltage is 55V, the sputtering power is 45W, the sputtering temperature is 120°C, the sputtering atmosphere is argon atmosphere, and the argon flow rate is 30sccm.

[0068] The specific process of depositing the first NiAl layer on the surface of the first NiZn layer by magnetron sputtering is as follows: the sputtering target is Ni2Al7 target, the sputtering power supply is RF power supply, the sputtering voltage is 75V, the sputtering power is 45W, the sputtering temperature is 120℃, the sputtering atmosphere is argon atmosphere, and the argon flow rate is 30sccm.

[0069] The specific process of depositing the second NiZn layer on the surface of the first NiAl layer by magnetron sputtering is as follows: the sputtering target is Ni3Zn4 target, the sputtering power supply is RF power supply, the sputtering voltage is 55V, the sputtering power is 75W, the sputtering temperature is 120℃, the sputtering atmosphere is argon atmosphere, and the argon flow rate is 30sccm.

[0070] The specific process for depositing the second NiAl layer on the surface of the second NiZn layer by magnetron sputtering is as follows: the sputtering target is a Ni2Al5 target, the sputtering power source is an RF power source, the sputtering voltage is 55V, the sputtering power is 75W, the sputtering temperature is 120°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30sccm. The number of cycles in Example 3 is 1215363.

[0071] Comparative Example 1

[0072] The method for physical vapor deposition-assisted laser shock strengthening of titanium alloys includes depositing a first NiZn layer on the titanium alloy surface via magnetron sputtering. The first NiAl layer, the second NiZn layer, and the second NiAl layer are not deposited. The thickness of the first NiZn layer is 1.5 microns, and the remaining parameters and processes are the same as in Example 1. The number of cycles in Comparative Example 1 is 1,053,578. It can be seen that if a single alloy layer is used, the protective effect of the alloy film on the titanium alloy is inferior to that of a pure metal film. A possible explanation for this phenomenon is that if an alloy film is used and the alloy film is required to reach a certain thickness (for example, referring to the explanation in CN116555709A, the alloy film must at least reach the thickness of the ablation layer during the laser strengthening treatment), then the film-forming ability of the alloy film may be inferior to that of the pure metal film, which will lead to too many defects inside the film layer. In this case, during the laser treatment, the internal defects of the alloy film reach "saturation" too early (it can be understood that the total amount of defects that can exist in a certain material is certain. If the number of defects reaches this total amount, the number of defects will not increase further, and cracks are obviously also a defect). Once the internal defects of the alloy film reach "saturation", the resistance to crack propagation inside the alloy film will increase rapidly, which prompts the crack to propagate toward the substrate, thus failing to achieve the corresponding purpose.

[0073] Comparative Example 2

[0074] The chemical formula of the first NiZn layer is Ni3Zn2, and the chemical formula of the second NiZn layer is Ni3Zn5. The chemical formula of the first NiAl layer is Ni2Al5, and the chemical formula of the second NiAl layer is Ni2Al9. The remaining parameters and processes are the same as those in Example 1. The number of cycles of Comparative Example 2 is 1104678 times. Comparative Example 2 proves that not all alloy films with multiple components stacked together have the effect of guiding cracks to expand in the direction of the metal film. A possible explanation for this phenomenon is that, as explained in Example 1, the reason why the alloy film of the present invention can better protect the laser-strengthened titanium alloy substrate is that the resistance to crack expansion inside the alloy film is small, and the alloy film can guide the cracks to expand in the direction away from the titanium alloy. However, when alloy films with other multiple components are stacked together, they may not be able to achieve the purpose of guiding cracks to expand in the direction away from the titanium alloy due to the intrinsic characteristics of each layer of material or the change in the interface strength between each film layer.

[0075] Comparative Example 3

[0076] The thickness of the first NiZn layer is 400 nm, the thickness of the first NiAl layer is 400 nm, the thickness of the second NiZn layer is 400 nm, and the thickness of the second NiAl layer is 400 nm. The remaining parameters and processes are the same as those in Example 1. The number of cycles of Comparative Example 3 is 1,164,770 times. The thickness difference between the various alloy film layers also has a certain influence on the crack propagation direction, which may be due to the fact that sputtering and depositing a thick film on a thin film can generate greater interfacial stress.

[0077] Comparative Example 4

[0078] The specific process for depositing a first NiZn layer on a titanium alloy surface by magnetron sputtering is as follows: a Ni3Zn5 target, an RF power supply, a sputtering voltage of 100 V, a sputtering power of 150 W, a sputtering temperature of 150°C, and an argon atmosphere at a flow rate of 30 sccm. The remaining parameters and processes were the same as in Example 1. The number of cycles in Comparative Example 4 was 1,134,892.

[0079] Comparative Example 5

[0080] The specific process for depositing the first NiAl layer on the surface of the first NiZn layer by magnetron sputtering is as follows: the sputtering target is a Ni2Al7 target, the sputtering power is an RF power supply, the sputtering voltage is 150 V, the sputtering power is 150 W, the sputtering temperature is 120°C, and the sputtering atmosphere is an argon atmosphere with an argon flow rate of 30 sccm. The remaining parameters and processes are the same as those in Example 1. The number of cycles in Comparative Example 5 is 1,144,792.

[0081] Comparative Example 6

[0082] The specific process for depositing a second NiZn layer on the surface of the first NiAl layer by magnetron sputtering is as follows: the sputtering target is a Ni3Zn4 target, the sputtering power is an RF power supply, the sputtering voltage is 150 V, the sputtering power is 150 W, the sputtering temperature is 120°C, and the sputtering atmosphere is an argon atmosphere with an argon flow rate of 30 sccm. The remaining parameters and processes are the same as those in Example 1. The number of cycles in Comparative Example 6 is 1,144,572.

[0083] Comparative Example 7

[0084] The specific process for depositing a second NiAl layer on the surface of the second NiZn layer by magnetron sputtering is as follows: the sputtering target is a Ni2Al5 target, the sputtering power source is an RF power source, the sputtering voltage is 55V, the sputtering power is 75W, the sputtering temperature is 120°C, and the sputtering atmosphere is an argon atmosphere with an argon flow rate of 30sccm. The remaining parameters and processes are the same as those in Example 1. The number of cycles in Comparative Example 7 is 1,154,782.

[0085] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for physical vapor deposition-assisted laser shock strengthening of titanium alloy, characterized in that: The method comprises: depositing a first NiZn layer on the titanium alloy surface by magnetron sputtering; depositing a first NiAl layer on the surface of the first NiZn layer by magnetron sputtering; depositing a second NiZn layer on the surface of the first NiAl layer by magnetron sputtering; depositing a second NiAl layer on the surface of the second NiZn layer by magnetron sputtering to obtain a coated titanium alloy to be strengthened; performing laser shock fatigue strengthening on the coated titanium alloy to be strengthened; After laser shock fatigue strengthening of the coated titanium alloy, the composite alloy film coated on the surface of the titanium alloy is removed by mechanical removal methods such as ultrasonic vibration, tape adhesion or friction; wherein the Ni content in the first NiZn layer is different from that in the second NiZn layer, and the Ni content in the first NiAl layer is different from that in the second NiAl layer, wherein the thickness of the first NiAl layer is at least 100 nm greater than that of the first NiZn layer, the thickness of the second NiZn layer is at least 100 nm greater than that of the first NiAl layer, and the thickness of the second NiAl layer is at least 100 nm greater than that of the second NiZn layer; Wherein, the chemical formula of the first NiZn layer is Ni3Zn5, and the chemical formula of the second NiZn layer is Ni3Zn4; Wherein, the chemical formula of the first NiAl layer is Ni2Al7, and the chemical formula of the second NiAl layer is Ni2Al5; The specific process of depositing the first NiZn layer on the titanium alloy surface by magnetron sputtering is as follows: The sputtering target is Ni3Zn5 target, the sputtering power supply is a radio frequency power supply, the sputtering voltage is 50-60V, the sputtering power is 40-50W, the sputtering temperature is 100-150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30-40sccm.

2. The method according to claim 1, wherein The thickness of the first NiZn layer is 50-100 nm, the thickness of the first NiAl layer is 200-300 nm, the thickness of the second NiZn layer is 400-500 nm, and the thickness of the second NiAl layer is 600-700 nm.

3. The method according to claim 2, wherein: The specific process of depositing the first NiAl layer on the surface of the first NiZn layer by magnetron sputtering is as follows: The sputtering target is Ni2Al7 target, the sputtering power supply is a radio frequency power supply, the sputtering voltage is 70-80V, the sputtering power is 40-50W, the sputtering temperature is 100-150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30-40sccm.

4. The method according to claim 3, wherein: The specific process of depositing the second NiZn layer on the surface of the first NiAl layer by magnetron sputtering is as follows: The sputtering target is Ni3Zn4 target, the sputtering power supply is a radio frequency power supply, the sputtering voltage is 50-60V, the sputtering power is 70-80W, the sputtering temperature is 100-150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30-40sccm.

5. The method according to claim 4, wherein The specific process of depositing the second NiAl layer on the surface of the second NiZn layer by magnetron sputtering is as follows: The sputtering target is Ni2Al5 target, the sputtering power supply is a radio frequency power supply, the sputtering voltage is 50-60V, the sputtering power is 70-80W, the sputtering temperature is 100-150°C, the sputtering atmosphere is an argon atmosphere, and the argon flow rate is 30-40sccm.

6. A titanium alloy subjected to laser shock fatigue strengthening, characterized in that: The titanium alloy is prepared by the method according to any one of claims 1 to 5.

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