Titanium / aluminum interface electronic cloud welding system and method based on spin polarization current regulation and control

Abstract

The invention relates to a titanium / aluminum interface electronic cloud welding system and method based on spin polarization current regulation and control. The welding system comprises a spin polarization electrode module, a quantum tunneling control module and a real-time monitoring and feedback module, the spin polarization electrode module comprises a titanium side Bi2Te2 electrode and an aluminum side CoFeB electrode which are connected, and a gap is formed between the connecting faces of the titanium side Bi2Te3 electrode and the aluminum side CoFeB electrode; the quantum tunneling control module comprises a piezoelectric control module, a welding head and an arc welding power supply; the real-time monitoring and feedback module comprises an electrical test unit, a thermal test unit and a controller. After spin polarization of electron cloud is achieved through the spin polarization electrode module, the spin polarization electrode module is combined with the quantum tunneling control module, titanium / aluminum interface electron cloud welding regulated and controlled by spin polarization current is achieved, and the real-time monitoring and feedback module conducts practice welding parameter precise adjustment. The method can effectively avoid generation of an IMC phase and prolong the fatigue life of a welding interface.

Description

Technical Field

[0001] The present invention relates to the technical field of electron cloud welding, and particularly relates to a titanium / aluminum interface electron cloud welding system and method based on spin-polarized current regulation. Background Art

[0002] When welding dissimilar alloys of titanium (Ti) and aluminum (Al), due to the Fermi level difference between the two metals (Ti: ~4.3 eV, Al: ~4.28 eV), the electron cloud distribution at the interface is mismatched, resulting in a charge transfer amount exceeding 0.5e - , triggering a strong electron cloud repulsion effect. This repulsive effect hinders the formation of metallic bonds between atoms, forcing the interface to form brittle intermetallic compounds (IMC phases, such as TiAl3) through lattice diffusion, severely reducing the joint conductivity and fatigue life (the interface resistance of traditional welded joints > 10 -6 Ω·cm 2 , and the fatigue life < 10 6 cycles).

[0003] Currently, the existing alloy welding technologies mainly include the following three:

[0004] 1. Magnetic field regulation of molten pool flow: By applying an external axial magnetic field (intensity 0.5 T) to change the flow direction of the molten pool, but only optimizing the molten pool morphology, unable to solve the problem of IMC phase nucleation caused by electron cloud repulsion.

[0005] 2. Electron beam welding: Commercial technologies use high-energy electron beams to bombard the interface, but the energy input is concentrated on the surface, resulting in local overheating (>2000 °C) and accelerating the coarsening of IMC phases.

[0006] 3. Cold pressure welding technology: It is necessary to apply extremely high pressure (>1 GPa) to force atoms to contact, but the residual oxide film at the interface leads to low bonding strength (<100 MPa).

[0007] Therefore, the existing technologies still fail to solve the following disadvantages in the welding of dissimilar alloys of titanium (Ti) and aluminum (Al):

[0008] 1. Electron cloud repulsion unresolved: The existing technologies do not regulate the electron state distribution at the Ti / Al interface, and the Fermi level difference leads to a charge transfer amount ΔQ > 0.5e - , triggering strong Coulomb repulsion (repulsion barrier > 1 eV).

[0009] 2. Uncontrollable heat input: Traditional welding relies on high temperatures to trigger atomic diffusion, resulting in the coarsening of IMC phases (average size > 500 nm).

[0010] 3. High interface resistance: The transition layer or oxide film makes the interface resistivity > 10 -6 Ω·cm 2, it cannot meet the requirements of high-conductivity scenarios.

[0011] Currently, there is still a need to improve the welding solutions and welding systems for dissimilar alloys to meet market demands. Summary of the Invention

[0012] The present invention provides a titanium / aluminum interface electron cloud welding system and method based on spin-polarized current regulation, aiming to solve the problems of electron cloud repulsion, heat input, and interface resistance in the welding of dissimilar alloys of titanium (Ti) and aluminum (Al).

[0013] To achieve the above object, the present invention provides a titanium / aluminum interface electron cloud welding system based on spin-polarized current regulation. The welding system includes a spin-polarized electrode module, a quantum tunneling control module, and a real-time monitoring and feedback module, wherein:

[0014] The spin-polarized electrode module includes a Bi2Te3 electrode on the titanium side and a CoFeB electrode on the aluminum side that are connected. There is a gap between the contact surfaces of the Bi2Te3 electrode on the titanium side and the CoFeB electrode on the aluminum side, and a quantum tunneling channel is formed in the gap. The spin polarization direction of electrons in the quantum tunneling channel is parallel to the magnetization direction of the CoFeB electrode on the aluminum side;

[0015] The quantum tunneling control module includes a piezoelectric control module, a welding head, and an arc welding power source. The piezoelectric control module is connected to the welding head to control the displacement of the welding head; the piezoelectric control module is connected to the arc welding power source to control the pulsed current provided by the arc welding power source;

[0016] The real-time monitoring and feedback module includes an electrical testing unit, a thermal testing unit, and a controller.

[0017] The core of the present invention is to regulate the electron cloud distribution at the titanium (Ti) / aluminum (Al) interface through spin-polarized current to achieve non-thermal-driven metal bonding; the system consists of three major modules: a spin-polarized electrode module, a quantum tunneling control module, and a real-time feedback and monitoring module.

[0018] Among the above three modules, the spin-polarized electrode module realizes the spin polarization of the electron cloud. The spin-polarized electron cloud has a quantum tunneling effect, making the interfacial charge transfer amount ΔQ < 0.1e - , and the repulsive potential barrier is reduced to less than 0.2 eV. Therefore, it has the following two advantages: First, it assists the electron cloud arc machining process to solve the strong Coulomb repulsion problem caused by the difference in electron state distribution and Fermi level at the Ti / Al interface; Second, it rotates the molten pool, controls the dispersion of the molten pool, inhibits the generation of IMC phases, and avoids the increase in interface resistivity caused by the coarsening of IMC phases.

[0019] The physical model of the quantum tunneling process is:

[0020] According to the Landauer formula, the tunneling probability where d is the electrode spacing, Φ is the work function of Ti, and E is the Fermi level of Al.

[0021] Therefore, after the spin-polarized electrode module realizes the spin polarization of the electron cloud and combines with the quantum tunneling control module, the electron cloud welding of the Ti / Al interface for spin-polarized current regulation can effectively solve the problems existing in the current welding process of Ti / Al dissimilar alloys, avoid the influence of the IMC phase on the interface resistivity, and improve the fatigue life of the interface of the welded joint. The real-time monitoring and feedback module plays a control role in the overall system to ensure the control and implementation of the overall welding scheme.

[0022] During the operation of the overall system, the Bi2Te3 electrode on the Ti side and the CoFeB electrode on the Al side not only play the role of spin-polarizing the electron cloud but also participate in providing the quantum tunneling channel. It is necessary to dynamically adjust the precise alignment between the interfaces of the control electrodes to maintain the best tunneling conditions; the spin polarization direction is parallel to the magnetization direction of the CoFeB electrode on the Al side to reduce the tunneling barrier.

[0023] The piezoelectric control module controls the precise displacement of the welding head on the one hand and also participates in outputting the arc on the other hand. According to the feedback control signal, it precisely adjusts parameters such as the pulse width, rise time, and repetition frequency to ensure that the change in the electron energy distribution meets the requirements of the tunneling process.

[0024] During the welding process, parameters such as the temperature rise and electrical properties of the interface will change in real time. The monitoring and feedback module can monitor these parameters in real time, such as monitoring the temperature rise of the interface through infrared thermal imaging and measuring the interface resistivity through the four-probe method, etc., and feeding the data back to the control system, so as to realize the precise control and optimization of the welding process. Without this module, relying only on the spin-polarized electrode module and the quantum tunneling control module, it is difficult to understand the parameter changes in the welding process in real time, and it is impossible to dynamically adjust and optimize the welding process, which may lead to unstable welding quality.

[0025] Preferably, the electron cloud welding system further includes a vacuum chamber, a water-cooled copper base, and a nano-positioning stage. The water-cooled copper base is arranged inside the vacuum chamber, and the nano-positioning stage is arranged on the water-cooled copper base.

[0026] Preferably, the Bi2Te3 electrode on the Ti side and the CoFeB electrode on the Al side are arranged on the nano-positioning stage, and the gap width between the interfaces of the Bi2Te3 electrode on the Ti side and the CoFeB electrode on the Al side is 1.95 - 2.05 nm;

[0027] The titanium alloy to be welded and the aluminum alloy to be welded are respectively arranged above the Bi2Te3 electrode on the Ti side and the CoFeB electrode on the Al side and fixed by fixtures.

[0028] The distance between the Bi2Te3 electrode on the titanium side and the CoFeB electrode on the aluminum side ranges from 2 ± 0.1 nm. Since the resolution of capacitance sensing is 0.1 fF corresponding to a spacing accuracy of 0.1 nm, and the vacuum gap is 2 ± 0.1 nm, it is dynamically adjusted through capacitance sensing feedback to ensure the stability of this spacing, with its fluctuation controlled within ±0.05 nm, ensuring that spin-polarized electrons can effectively tunnel and realizing the recombination of the interfacial electron cloud. This can optimize the tunneling probability, make the tunneling current density reach the expected value, thus achieving efficient electron tunneling and interfacial bonding, precisely regulating the quantum tunneling effect, avoiding problems such as too low tunneling probability due to too large a spacing or strong electron cloud repulsion caused by too small a spacing, and then improving the welding quality and performance.

[0029] Preferably, the electrical testing unit and the thermal testing unit are arranged inside the vacuum chamber, where the electrical testing unit and the thermal testing unit respectively monitor the interfacial resistance and temperature at the welding interface of the titanium alloy to be welded and the aluminum alloy to be welded.

[0030] Preferably, the controller and the arc welding power source are arranged outside the vacuum chamber. The controller is respectively connected to the electrical testing unit and the thermal testing unit, and is also connected to the piezoelectric control module.

[0031] The controller will comprehensively optimize various parameters during the entire welding process according to the resistance and temperature rise data fed back by the electrical and thermal testing units:

[0032] 1. Welding spacing adjustment: The capacitance sensing feedback system will continuously monitor the capacitance change corresponding to the electrode spacing. The controller controls the displacement of the welding head based on this information to ensure that the distance between the welding head and the electrode is stable at the target value (such as 2 nm) with extremely small fluctuations (such as ±0.05 nm) to maintain the best tunneling conditions.

[0033] 2. Pulse current parameter adjustment: In addition to the magnitude of the pulse current, it also includes the adjustment of parameters such as the pulse width, rise time, and repetition frequency; precisely control the pulse width at 1 ns (full width at half maximum), the rise time at 100 ps, and the repetition frequency at 1 kHz, etc., to ensure the narrowing of the electron energy distribution and meet the requirements of the tunneling process;

[0034] 3. Electrode attitude adjustment: Use a nano-positioning stage to finely adjust the attitude of the electrodes, precisely adjust the distance between the Bi2Te3 electrode on the titanium side and the CoFeB electrode on the aluminum side, ensure the alignment accuracy between the electrodes, and make the welding process more stable and precise.

[0035] Preferably, a piezoelectric ceramic driver is arranged inside the piezoelectric control module. The piezoelectric ceramic driver is connected to the welding head to adjust the displacement of the welding head. The controller feeds back information to control the piezoelectric ceramic, and the piezoelectric ceramic further precisely adjusts the displacement of the welding head.

[0036] The parameter adjustment of the welding head by the piezoelectric control module needs to meet the requirements of collaborative control of precise displacement and pulsed current: in terms of mechanical displacement, the welding head is driven by the built-in piezoelectric ceramic driver to achieve nanoscale precision adjustment. According to the capacitance sensing feedback, the distance between the welding head and the electrode is corrected in real time to the target value (such as 2 nm), and the displacement fluctuation is controlled within ±0.05 nm to ensure the stability of the quantum tunneling channel; in terms of pulsed current parameters, the pulsed amplitude (such as 10 V), pulse width (1 ns full width at half maximum), rise time (100 ps), and repetition frequency (1 kHz) output by the arc welding power supply through the welding head are precisely regulated, and shaped into Gaussian pulses through the RLC network to narrow the electron energy distribution (full width at half maximum < 0.1 eV) to match the tunneling probability requirement; at the same time, combined with the interface resistance (≤10 -8 Ω·cm 2 ) and temperature rise (≤10 K) data fed back by the real-time monitoring module, the displacement trajectory of the welding head and the pulsed output timing are dynamically adjusted to suppress the interface heat accumulation and electron cloud repulsion, and achieve the efficient tunneling of spin-polarized electrons and the recombination of the interface electron cloud.

[0037] Preferably, the arc welding power supply applies pulsed current and is integrated with the wire feeder into the piezoelectric control module through a cable for arc output and wire feeding.

[0038] Under the same technical concept, the present invention also provides a method for welding the interface electron cloud of titanium / aluminum based on the regulation of spin-polarized current. The method for welding the interface electron cloud of titanium / aluminum based on the regulation of spin-polarized current uses the system for welding the interface electron cloud of titanium / aluminum based on the regulation of spin-polarized current described above.

[0039] Preferably, the method specifically includes the following steps:

[0040] S1. The Bi2Te3 electrode on the titanium side and the CoFeB electrode on the aluminum side are arranged on the nano-positioning stage, and the vacuum degree in the vacuum chamber is controlled to be 10 -5 Torr or above; the high vacuum inside the electron cloud welding system is controlled;

[0041] S2. The nano-positioning stage controls the precise alignment of the Bi2Te3 electrode on the titanium side and the CoFeB electrode on the aluminum side, and adjusts the gap width between the contact surfaces of the Bi2Te3 electrode on the titanium side and the CoFeB electrode on the aluminum side to be 1.95 - 2.05 nm;

[0042] S3. Place the titanium alloy to be welded and the aluminum alloy to be welded above the Bi2Te3 electrode on the titanium side and the CoFeB electrode on the aluminum side, with their welding interfaces in close contact, fixed by a fixture, the arc welding power supply applies pulsed current, and under the drive of the pulsed current, the spin-polarized electrons tunnel from the electrode on the titanium side to the electrode on the aluminum side to recombine the interface electron cloud for electron cloud welding;

[0043] S4. The real-time monitoring and feedback module monitors the resistance and temperature rise in real time, and feeds back to the controller. The controller optimizes the parameters according to the feedback results and transmits them to the piezoelectric control module. The piezoelectric control module controls the arc welding power source and the welding head for dynamic adjustment until the welding is completed.

[0044] During the electron cloud welding process at the titanium-aluminum interface, appropriate welding conditions are first established through the spin-polarized electrode module. In this application, a Bi2Te3 single crystal electrode is used on the titanium side, which has an extremely low surface roughness. And in ultra-high vacuum, the oxide layer is removed by argon ion etching, and a thin gold film is deposited to reduce the contact resistance. On the aluminum side, a CoFeB amorphous thin film electrode is used to ensure high saturation magnetization intensity and good amorphous structure. When assembling the electrode interface, the electrode spacing is precisely controlled at about 2 nm to ensure the stability of the tunneling current signal.

[0045] Next, the quantum tunneling control module plays a key role. The arc welding power source generates high-voltage narrow pulses with specific parameters and applies them to the welding interface. The spin-polarized electrons tunnel from the titanium-side electrode to the aluminum-side electrode under the drive of the pulsed electric field. During this process, the spin polarization direction of the electrons is parallel to the magnetization direction of the aluminum-side electrode, reducing the tunneling barrier and improving the tunneling efficiency. At the same time, the real-time feedback and monitoring module monitors the entire welding process, and through infrared thermal imaging and Raman spectroscopy technologies, ensures that the interface temperature rise is controlled within 10 K to verify the non-thermal bonding characteristics.

[0046] Preferably, the real-time monitoring of resistance and temperature rise, feedback and optimization of parameters specifically include: during the electron cloud welding, controlling the temperature rise at the welding interface ≤10k and the interface resistivity ≤10 -8 Ω·cm 2 .

[0047] The above solution of the present invention has the following beneficial effects:

[0048] (1) The present invention provides a titanium / aluminum interface electron cloud welding system based on spin-polarized current regulation, including a spin-polarized electrode module, a quantum tunneling control module and a real-time monitoring and feedback module. It combines spin polarization with electron cloud welding and adjusts and feeds back the parameters in real time. The combination of each module jointly realizes the spin-polarized current-regulated titanium / aluminum interface electron cloud welding;

[0049] (2) The welding method of the present invention can utilize the quantum tunneling effect of spin-polarized electrons to eliminate the electron cloud repulsion, so that the charge transfer amount ΔQ at the welding interface <0.1e - , and the repulsive barrier is reduced to below 0.2 eV; and due to non-thermal bonding, the high-temperature process can be avoided, the interface temperature rise <10 K, and the generation of IMC phase is completely inhibited;

[0050] (3) The alloy obtained by welding in the present invention has an ultra-low interfacial resistance and excellent fatigue performance, and can achieve an interfacial resistivity ≤ 10 -8 Ω·cm 2 , and a fatigue life ≥ 10 9 cycles.

[0051] Other beneficial effects of the present invention will be described in detail in the following specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a schematic front cross-sectional view of the structure of the titanium / aluminum interfacial electron cloud welding system based on spin-polarized current regulation of the present invention;

[0053] Figure 2 is a schematic side and top-down cross-sectional view of the structure of the titanium / aluminum interfacial electron cloud welding system based on spin-polarized current regulation of the present invention;

[0054] Among them, 1, vacuum chamber; 2, water-cooled copper base; 3, nano-positioning stage; 4, Bi2Te3 electrode on the titanium side; 5, fixture; 6, titanium alloy to be welded; 7, aluminum alloy to be welded; 8, CoFeB electrode on the aluminum side; 9, electrical testing unit; 10, welding head; 11, piezoelectric control module; 12, thermal testing unit; 13, controller; 14, arc welding power supply. DETAILED DESCRIPTION OF THE INVENTION

[0055] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0056] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0057] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0059] As Figure 1 、 2 shown, an electron cloud welding system based on spin-polarized current regulation for a titanium / aluminum interface according to an embodiment of the present invention includes a spin-polarized electrode module, a quantum tunneling control module, and a real-time monitoring and feedback module. The spin-polarized electrode module includes a titanium-side Bi2Te3 electrode 4 and an aluminum-side CoFeB electrode 8 that are connected. There is a gap between the contact surfaces of the titanium-side Bi2Te3 electrode 4 and the aluminum-side CoFeB electrode 8, and a quantum tunneling channel is formed in the gap. The spin polarization direction of the electrons in the quantum tunneling channel is parallel to the magnetization direction of the aluminum-side CoFeB electrode 8;

[0060] The quantum tunneling control module includes a piezoelectric control module 11, a welding head 10, and an arc welding power source 14. The piezoelectric control module 11 is connected to the welding head 10 to control the displacement of the welding head 10; the piezoelectric control module 11 is connected to the arc welding power source 14 to control the pulsed current provided by the arc welding power source 14;

[0061] The real-time monitoring and feedback module includes an electrical testing unit 9, a thermal testing unit 12, and a controller 13.

[0062] The electron cloud welding system further includes a vacuum chamber 1, a water-cooled copper base 2, and a nano-positioning stage 3. The water-cooled copper base 2 is disposed inside the vacuum chamber 1, and the nano-positioning stage 3 is disposed on the water-cooled copper base 2.

[0063] The titanium-side Bi2Te3 electrode 4 and the aluminum-side CoFeB electrode are disposed on the nano-positioning stage 3, and the nano-positioning stage 3 regulates the gap width between the contact surfaces of the titanium-side Bi2Te3 electrode 4 and the aluminum-side CoFeB electrode 8 to be 1.95 - 2.05 nm.

[0064] The titanium alloy 6 to be welded and the aluminum alloy 7 to be welded are respectively disposed above the titanium-side Bi2Te3 electrode 4 and the aluminum-side CoFeB electrode 8 and fixed by a fixture 5.

[0065] The electrical testing unit 9 and the thermal testing unit 12 are arranged inside the vacuum chamber 1, wherein the electrical testing unit 9 and the thermal testing unit 12 respectively monitor the interface resistance and temperature at the welding interfaces of the titanium alloy 6 to be welded and the aluminum alloy 7 to be welded.

[0066] The controller 13 and the arc welding power source 14 are arranged outside the vacuum chamber 1. The controller 13 is respectively connected to the electrical testing unit 9 and the thermal testing unit 12, and is connected to the piezoelectric control module 11.

[0067] A piezoelectric ceramic driver is arranged inside the piezoelectric control module 11. The piezoelectric ceramic driver is connected to the welding head 10 to adjust the displacement of the welding head 10. The arc welding power source 14 applies a pulsed current and is integrated with the wire feeder through a cable into the piezoelectric control module 11 to perform arc output and wire feeding of the welding wire.

[0068] This embodiment also provides a titanium / aluminum interface electron cloud welding method based on the regulation of spin-polarized current, adopting the titanium / aluminum interface electron cloud welding system based on the regulation of spin-polarized current.

[0069] The method specifically includes the following steps:

[0070] S1. Build a titanium / aluminum interface electron cloud welding system based on the regulation of spin-polarized current, including structures such as the vacuum chamber 1, the water-cooled copper base 2, and the six-axis nano-positioning stage 3. Process the titanium-side Bi2Te3 electrode 4 and the aluminum-side CoFeB electrode 8 respectively. The titanium-side electrode uses a topological insulator Bi2Te3 single crystal, and undergoes processes such as mechanical polishing, argon ion etching, and gold thin film deposition. The aluminum-side electrode selects a ferromagnetic CoFeB amorphous thin film and is prepared through steps such as magnetron sputtering and vacuum annealing. Place the processed titanium-side Bi2Te3 electrode 4 and aluminum-side CoFeB electrode 8 on the nano-positioning stage 3, and control the vacuum degree in the vacuum chamber 1 to be 10 -5 Torr or above;

[0071] S2. The nano-positioning stage 3 controls the precise alignment of the titanium-side Bi2Te3 electrode 4 and the aluminum-side CoFeB electrode 8, and adjusts the gap width between the contacting surfaces of the titanium-side Bi2Te3 electrode 4 and the aluminum-side CoFeB electrode 8 to be 1.95 - 2.05 nm;

[0072] S3. Place the titanium alloy 6 to be welded and the aluminum alloy 7 to be welded respectively above the titanium-side Bi2Te3 electrode 4 and the aluminum-side CoFeB electrode 8, fix them with the fixture 5, and the arc welding power source 14 applies a pulsed current to generate a high-voltage narrow pulse with an amplitude of 10 V, a pulse width of 1 ns, a rise time of 100 ps, and a repetition frequency of 1 kHz, driving the spin-polarized current to pass through the titanium-aluminum interface. The spin-polarized electrons tunnel from the titanium-side electrode to the aluminum-side electrode under the drive of the pulse, reorganize the interface electron cloud, and perform electron cloud welding;

[0073] S4. The real-time monitoring and feedback module monitors the resistance and temperature rise in real time. An infrared thermal imager is used to monitor the interface temperature rise in real time to ensure that the temperature rise is <10K. The four-probe method is used to measure the interface resistivity, and the test results show that the interface resistivity ≤ 10 -8 Ω·cm 2 ; it is fed back to the controller 13. The controller 13 optimizes the parameters according to the feedback results and transmits them to the piezoelectric control module 11. The piezoelectric control module 11 controls the arc welding power source 14 and the welding head 10 for dynamic adjustment until the welding is completed, obtaining a titanium / aluminum alloy for electron cloud welding of the titanium / aluminum interface regulated by spin-polarized current.

[0074] During the welding process, the adjustment of various parameters is specifically as follows:

[0075] Pulse current:

[0076] Pulse parameters: amplitude 10V, pulse width 1ns (full width at half maximum), rise time 100ps, repetition frequency 1kHz.

[0077] Waveform optimization: The Gaussian pulse is shaped by the RLC filter network to ensure the narrowing of the electron energy distribution (full width at half maximum <0.1eV).

[0078] Current density control: By precisely matching the electrode area (1mm 2 ) with the pulse amplitude, a current density of 106A / cm 2 (error ±5%) is achieved.

[0079] Physical model of the tunneling process:

[0080] According to the Landauer formula, the tunneling probability

[0081] where: d = 2nm (electrode spacing)

[0082] Φ = 4.3eV (Ti work function)

[0083] E = 4.28eV (Al Fermi level)

[0084] Calculated to get T(E) ≈ 10 -2 , corresponding to the tunneling current density J = e·T(E)·N(E)·v ≈ 10 6 A / cm 2 .

[0085] Verification of the spin polarization rate:

[0086] The electrons in the surface state of Bi2Te3 are accelerated by the pulsed electric field and cross the 2nm vacuum gap into the CoFeB electrode.

[0087] The spin polarization direction is parallel to the magnetization direction of CoFeB, reducing the tunneling barrier;

[0088] Spin-polarized scanning tunneling microscope (SP-STM): A transverse magnetic field (0.5 T) is applied to the tip, the dependence of the tunneling current on the magnetic field is measured, and the spin polarization rate > 90% is calculated.

[0089] Real-time monitoring of resistance and temperature rise mainly includes the following:

[0090] 1. Thermodynamic monitoring

[0091] Infrared thermal imaging: A mid-wave infrared camera (spectral range 3 - 5 μm, spatial resolution 3 μm) is used to monitor the interface temperature rise in real time (sensitivity 0.02 K).

[0092] Raman spectroscopy: A 532 nm laser light source is used to detect changes in the interface lattice vibration mode (resolution 0.5 cm-1) to verify the non-thermal bonding characteristics.

[0093] 2. Electrical property testing

[0094] Four-probe method: The interface resistivity is measured with a probe spacing of 25 μm and a current range of 1 nA - 1 mA (Keithley 2450 source meter).

[0095] Fatigue life test: A high-frequency hydraulic servo system (frequency 10 Hz, load ±50 MPa) is used to record the number of failure cycles of the joint.

[0096] The test results show that the interface resistivity ≤ 10 -8 Ω·cm 2 and the fatigue life ≥ 10 9 cycles.

[0097] The surface of the weld area of the titanium / aluminum alloy by electron cloud welding of titanium / aluminum based on spin-polarized current regulation is flat and smooth, without common pores, cracks, oxidation spots or molten pool splash marks in traditional welding. The color is uniform and the transition with the base material is natural, without obvious color difference in the heat-affected zone; due to the non-thermal bonding process inhibiting the formation of brittle intermetallic compounds, the interface bonding shows a continuous and dense macroscopic feature, without local protrusions or depressions, and the edge contour is clear and regular, reflecting the uniform bonding effect under nanoscale precision control. Compared with the rough surface and heat damage marks of traditional welded joints, the appearance quality and consistency are significantly improved.

[0098] The welded specimen is placed in a high-frequency hydraulic servo system for fatigue life testing. Under the conditions of a frequency of 10 Hz and a load of ±50 MPa, the number of failure cycles of the joint is recorded, and the number of failure cycles of the joint reaches 1.2×10 9 cycles, and the interface resistivity measured by the four-probe method is 8.5×10 -9 Ω·cm 2 .

[0099] The atomic structure of the interface was observed by HAADF-STEM, and combined with EELS analysis, it was confirmed that no IMC phase was generated at the interface; the VASP software was used to calculate the interfacial charge density difference. The interfacial charge transfer amount ΔQ = 0.05e - , the repulsive barrier is 0.15 eV; the interfacial temperature rise was measured to be ≤10 K, and the generation of the IMC phase was completely inhibited.

[0100] The above are the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle described in the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A titanium / aluminum interface electron cloud welding system regulated by spin-polarized current, characterized in that The welding system includes a spin-polarized electrode module, a quantum tunneling control module, and a real-time monitoring and feedback module, where: The spin-polarized electrode module includes a titanium-side Bi2Te3 electrode (4) and an aluminum-side CoFeB electrode (8) that are connected. There is a gap between the contact surfaces of the titanium-side Bi2Te3 electrode (4) and the aluminum-side CoFeB electrode (8). A quantum tunneling channel is formed in the gap, and the spin polarization direction of electrons in the quantum tunneling channel is parallel to the magnetization direction of the aluminum-side CoFeB electrode (8); The quantum tunneling control module includes a piezoelectric control module (11), a welding head (10), and an arc welding power source (14). The piezoelectric control module (11) is connected to the welding head (10) to control the displacement of the welding head (10); the piezoelectric control module (11) is connected to the arc welding power source (14) to control the pulsed current provided by the arc welding power source (14); The real-time monitoring and feedback module includes an electrical testing unit (9), a thermal testing unit (12), and a controller (13).

2. The electron cloud welding system according to claim 1, characterized in that, The electron cloud welding system further includes a vacuum chamber (1), a water-cooled copper base (2), and a nano-positioning stage (3). The water-cooled copper base (2) is arranged inside the vacuum chamber (1), and the nano-positioning stage (3) is arranged on the water-cooled copper base (2).

3. The electron cloud welding system according to claim 2, wherein The titanium-side Bi2Te3 electrode (4) and the aluminum-side CoFeB electrode (8) are arranged on the nano-positioning stage (3). The nano-positioning stage (3) adjusts the gap width between the contact surfaces of the titanium-side Bi2Te3 electrode (4) and the aluminum-side CoFeB electrode (8) to be 1.95 - 2.05 nm; The titanium alloy to be welded (6) and the aluminum alloy to be welded (7) are respectively arranged above the titanium-side Bi2Te3 electrode (4) and the aluminum-side CoFeB electrode (8), and are fixed by a fixture (5).

4. The electron cloud welding system according to claim 3, characterized in that, The electrical testing unit (9) and the thermal testing unit (12) are arranged inside the vacuum chamber (1). Among them, the electrical testing unit (9) and the thermal testing unit (12) respectively monitor the interface resistance and temperature at the welding interface of the titanium alloy to be welded (6) and the aluminum alloy to be welded (7).

5. The electron cloud welding system according to claim 2, characterized in that, The controller (13) and the arc welding power source (14) are arranged outside the vacuum chamber (1). The controller (13) is respectively connected to the electrical testing unit (9) and the thermal testing unit (12), and is connected to the piezoelectric control module (11).

6. The electron cloud welding system according to claim 1, wherein, A piezoelectric ceramic driver is arranged inside the piezoelectric control module (11). The piezoelectric ceramic driver is connected to the welding head (10) to adjust the displacement of the welding head (10).

7. The electron cloud welding system according to claim 1, wherein The arc welding power source (14) applies a pulsed current and is integrated with a wire feeder through a cable into the piezoelectric control module (11) to perform arc output and wire feeding of the welding wire.

8. A method for electron cloud welding of titanium / aluminum interface regulated by spin-polarized current, characterized in that, The titanium / aluminum interface electron cloud welding based on spin-polarized current regulation uses the titanium / aluminum interface electron cloud welding system based on spin-polarized current regulation according to any one of claims 1 - 6.

9. The electron cloud welding method according to claim 8, characterized in that, The method specifically includes the following steps: S1. Place the Bi2Te3 electrode (4) on the titanium side and the CoFeB electrode (8) on the aluminum side on the nano-positioning stage (3), and control the vacuum degree in the vacuum chamber (1) to be 10 -5 Torr or higher; S2. The nano-positioning stage (3) controls the precise alignment of the Bi2Te3 electrode (4) on the titanium side and the CoFeB electrode (8) on the aluminum side, and adjusts the gap width between the contact surfaces of the Bi2Te3 electrode (4) on the titanium side and the CoFeB electrode (8) on the aluminum side to be 1.95 - 2.05 nm; S3. Place the titanium alloy to be welded (6) and the aluminum alloy to be welded (7) above the Bi2Te3 electrode (4) on the titanium side and the CoFeB electrode (8) on the aluminum side, with their welding interfaces in close contact, fix them with a fixture (5), and apply a pulsed current with an arc welding power source (14). The spin-polarized electrons tunnel from the electrode on the titanium side to the electrode on the aluminum side under the drive of the pulsed current, recombine the electron cloud at the interface, and perform electron cloud welding; S4. The real-time monitoring and feedback module monitors the resistance and temperature rise in real time and feeds back to the controller (13). The controller (13) optimizes the parameters according to the feedback results and transmits them to the piezoelectric control module (11). The piezoelectric control module (11) controls the arc welding power source (14) and the welding head (10) for dynamic adjustment until the welding is completed.

10. The electronic cloud welding method according to claim 9, characterized in that, The real-time monitoring of resistance and temperature rise, feedback and optimization of parameters specifically include: during electron cloud welding, controlling the temperature rise at the welding interface ≤ 10k and the interface resistivity ≤ 10 -8 Ω·cm 2 .

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