Lithium-magnesium metal film preparation method and magnesium-lithium diaphragm driver

Abstract

The invention relates to the technical field of sound equipment, in particular to a lithium-magnesium metal film preparation method and a magnesium-lithium diaphragm driver. According to the preparation method, a special lithium-magnesium alloy material is subjected to forging, rolling, cutting, hot stamping and micro-arc oxidation strengthening treatment; the obtained lithium-magnesium metal film is high in rigidity, lower in density, higher in sensitivity, higher in damping coefficient, lower in distortion and better in sound quality improvement effect. The driver adopts sound-absorbing cotton, a voice coil, a phase plug, and a cover body, a support, a vibrating diaphragm and a magnetic circuit assembly which are connected in sequence, the characteristics of low density, high rigidity and large damping ratio of a lithium-magnesium metal film are utilized, the high-frequency response speed can be improved, harmonic distortion can be reduced, and meanwhile, the sound-absorbing cotton is utilized for absorbing reflected sound waves of the back surface of the vibrating diaphragm and an inner cavity of the cover body, so that the sound-absorbing effect is improved. Standing wave and clutter interference generated by internal reflection and diffraction of sound waves is reduced, distortion is further reduced, the sound is purer and clearer, and the overall acoustic quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sound equipment, in particular to a lithium-magnesium metal film preparation method and a magnesium-lithium diaphragm driver. BACKGROUND

[0002] The compression driver is an important component in the loudspeaker system, which is used to convert electrical signals into mechanical vibrations and produce sound. It is usually composed of a diaphragm, a magnetic circuit system and a throat, etc. The diaphragm is one of the most core parts in the compression driver, which converts electrical signals into sound output through mechanical vibration. It is usually made of polyester film or polyimide film, which has the characteristics of lightness, firmness, fast response, etc. The magnetic circuit system is another important component, including ferrite magnet, front iron plate and back iron plate, etc. elements, used to generate and control a strong magnetic field. The throat is a slender pipe connecting the diaphragm and the magnetic circuit system, used to control the transmission and amplification of sound.

[0003] However, the existing driver is easily affected by the structure of the diaphragm, phase plug and cover, etc., which can cause slow high-frequency response speed, insufficient sensitivity, poor high-frequency extension, and large harmonic distortion, resulting in driver sound and low sound quality.

[0004] In addition, the existing diaphragm is mostly made of titanium or aluminum. Among them, the titanium diaphragm has good rigidity, but its density is large, which makes the diaphragm mass heavier and affects the high-frequency response speed. The aluminum diaphragm has low density, but its rigidity is insufficient, and it is easy to age due to thermal expansion and other factors after long-term use, and the acoustic performance decays obviously. Even if there is a magnesium-lithium alloy diaphragm, although it can achieve a relatively low density of 1.35-1.65 g / cm 3 , its damping coefficient is still insufficient, and the improvement effect on sound quality needs to be improved. SUMMARY

[0005] In order to overcome the shortcomings and deficiencies in the prior art, one of the purposes of the present application is to provide a lithium-magnesium metal film preparation method.

[0006] The second purpose of the present application is to provide a driver with a lithium-magnesium diaphragm.

[0007] One of the purposes of the present application is achieved by the following technical scheme: a lithium-magnesium metal film preparation method, comprising the following steps: (S1), taking each raw material to obtain a lithium-magnesium alloy material after vacuum melting; (S2), deforming the lithium-magnesium alloy material by 350-400℃ forging to make the deformation amount ≥70%, and then rolling under the condition of 250-300℃ and total reduction ratio ≥85% to obtain a lithium-magnesium alloy foil with a thickness of 0.05mm-0.4mm; (S3), according to the size specification requirements of the diaphragm of the driver, the lithium-magnesium alloy foil is cut, then hot-stamped at 200-250 DEG C and kept for 1-2 min to form a molded film; (S4), the molded film is placed in a silicate electrolyte, and micro-arc oxidation strengthening treatment is carried out at a current density of 5-10 A / dm 2 for 15-20 h to form a ceramic oxide film with a thickness of 10-20 μm on the surface of the molded film, thereby obtaining a lithium-magnesium metal film; The lithium-magnesium alloy material comprises the following components in the following percentages: 54.0-56.8% Li, 36.0-37.8% Mg, 2-4% Si, 2-4% C, 0-2% Al, 0-2% Zn, 0-0.5% Cd, 0-0.3% Ca, 0-0.8% Sr, 0-1% Re, 1-2% Cu, 0.3-0.8% Zr, and the balance is impurities, wherein the content of each impurity is less than 0.03%, and the total content of the impurities is less than 0.15%.

[0008] Preferably, in the step (S1), the vacuum smelting conditions are as follows: vacuum degree ≤5*10-3 Pa, smelting temperature 720-780 DEG C, and holding time 2-3 h; in the step (S2), the surface flatness deviation of the lithium-magnesium alloy foil is ≤0.02 mm; and in the step (S3), the molded film ensures that the diaphragm surface is flat and the size precision error is ≤0.05 mm.

[0009] Preferably, in the step (S4), the silicate electrolyte comprises 10-15 g / L sodium silicate, 0.5-1 g / L sodium hydroxide and 0.2-0.5 g / L sodium fluoride.

[0010] The second object of the application is achieved by the following technical scheme: a driver with a lithium-magnesium diaphragm, comprising sound-absorbing cotton, a voice coil, a phase plug, and a cover, a support, a diaphragm and a magnetic circuit assembly connected in sequence, wherein the magnetic circuit assembly has an annular magnetic gap, one end of the voice coil is fixedly bonded to one side of the diaphragm close to the magnetic circuit assembly, the other end of the voice coil extends into the annular magnetic gap, the phase plug is fixedly connected to the middle part of the magnetic circuit assembly, the sound-absorbing cotton is attached to one side of the cover close to the diaphragm, and the diaphragm is prepared by the lithium-magnesium metal film preparation method described above.

[0011] Preferably, a ring-shaped groove is formed in one side of the support attached to the cover, and a sealing ring is arranged between the ring-shaped groove and the cover.

[0012] Preferably, the phase plug is an aluminum alloy phase plug, the cover is an aluminum alloy cover, and the voice coil is a copper-clad aluminum wire voice coil.

[0013] Preferably, the magnetic circuit assembly comprises a dust shield, a magnet ring and a T-shaped iron in sequence, the dust shield is attached to the side of the dust shield away from the magnet ring, the T-shaped iron has a receiving through hole in the middle of the core column, and the phase plug is fixedly connected to the inner side wall of the receiving through hole.

[0014] Preferably, the driver further comprises a copper short-circuit ring fixedly attached to the outer side wall of the core column of the T-shaped iron, and an aluminum short-circuit ring fixedly attached to the outer side wall of the copper short-circuit ring.

[0015] Preferably, the cover body is provided with a plurality of annularly distributed mounting through holes, the dust shield is provided with a plurality of screw holes in one-to-one correspondence with the mounting through holes, and the cover body is fixedly connected to the dust shield through screws.

[0016] Preferably, the magnet ring is a neodymium-iron-boron magnet with a residual magnetization Br of greater than or equal to 1.23 T and a coercive force Hc of greater than or equal to 915 kA / m, and the annular magnetic gap has a spacing of 0.2-0.3 mm.

[0017] The lithium-magnesium metal film preparation method of the present application has the advantages that the lithium-magnesium metal film obtained by the method has a density of only 1.21-1.26 g / cm 3 , while ensuring high rigidity with a Young's modulus of greater than or equal to 45 GBa, so that the driver provides higher sensitivity, has a small thermal expansion coefficient, strong anti-aging ability, stable acoustic performance in long-term use, and controllable material processing, and the thickness can be accurately processed in the range of 0.05 mm-0.4 mm to adapt to the structure requirements of various loudspeakers, the damping coefficient can be greater than or equal to 0.02, which is about 12 times that of conventional metals (aluminum and titanium), and is higher than that of the existing magnesium-lithium alloy diaphragm, which is more conducive to reducing the harmonic distortion of the driver and providing better sound quality.

[0018] The driver with a lithium-magnesium diaphragm of the present application adopts sound-absorbing cotton, a voice coil, a phase plug, and a cover body, a bracket, a diaphragm and a magnetic circuit assembly connected in sequence, the magnetic circuit assembly has an annular magnetic gap, one end of the voice coil is fixedly bonded to one side of the diaphragm close to the magnetic circuit assembly, the other end of the voice coil extends into the annular magnetic gap, the phase plug is fixedly connected to the middle part of the magnetic circuit assembly, the sound-absorbing cotton is attached to one side of the cover body close to the diaphragm, and the diaphragm is prepared by the above lithium-magnesium metal film preparation method. Its low density, high rigidity and large damping ratio characteristics of the lithium-magnesium metal film can improve the high-frequency response speed and reduce the harmonic distortion, at the same time, the sound-absorbing cotton can absorb the reflected sound waves in the back of the diaphragm and the inner cavity of the cover body, reduce the standing wave and interference of stray waves generated by the reflection and diffraction of sound waves inside, further reduce distortion, make the sound more pure and clear, and improve the overall acoustic quality. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic diagram of the present application; Figure 2is a disassembled schematic view of the present application; Figure 3 is a disassembled schematic view of another perspective of the present application; Figure 4 is a cross-sectional schematic view of the present application; Figure 5 is a frequency response and distortion chart of the present application, wherein the red curve is the frequency response test result of the driver with the lithium-magnesium diaphragm of Example 1, the green curve is the frequency response test result of the commercially available loudspeaker driver of Comparative Example 1, the yellow curve is the distortion rate test result of the driver with the lithium-magnesium diaphragm of Example 1, and the blue curve is the distortion rate test result of the commercially available loudspeaker driver of Comparative Example 1.

[0020] The reference signs are: 1, sound-absorbing cotton; 2, voice coil; 3, phase plug; 4, cover body; 5, support; 6, diaphragm; 7, magnetic circuit assembly; 71, dust shield; 72, magnet ring; 73, T-shaped iron; 8, annular magnetic gap; 9, annular groove; 10, sealing ring; 11, accommodating through hole; 12, copper short-circuit ring; 13, aluminum short-circuit ring; 14, mounting through hole; 15, screw hole; 16, screw; 17, dust screen; 18, annular gasket. DETAILED DESCRIPTION

[0021] For the convenience of understanding of those skilled in the art, the present application is further described below in combination with examples and drawings, and the content mentioned in the embodiments is not a limitation on the present application.

[0022] In a typical embodiment of the present application, a lithium-magnesium metal film preparation method comprises the following steps: (S1), taking each raw material to obtain a lithium-magnesium alloy material after vacuum smelting; (S2), deforming the lithium-magnesium alloy material by forging at 350-400℃ to make the deformation amount ≥70%, and then rolling under the condition of 250-300℃ and total reduction ratio ≥85% to obtain a lithium-magnesium alloy foil with a thickness of 0.05mm-0.4mm; (S3), according to the size specification requirements of the diaphragm of the driver, the lithium-magnesium alloy foil is cut and then formed by hot stamping under the condition of 200-250℃ and heat preservation for 1-2min to obtain a formed film; (S4), placing the formed film in a silicate electrolyte, and performing micro-arc oxidation strengthening treatment on the formed film under the condition of current density 5-10A / dm 2 , oxidation time 15-20h to form a ceramic oxide film with a thickness of 10-20μm on the surface of the formed film, thereby obtaining a lithium-magnesium metal film; The lithium-magnesium alloy material comprises the following components in percentage: 54.0-56.8% Li, 36.0-37.8% Mg, 2-4% Si, 2-4% C, 0-2% Al, 0-2% Zn, 0-0.5% Cd, 0-0.3% Ca, 0-0.8% Sr, 0-1% Re, 1-2% Cu, 0.3-0.8% Zr, and the balance is impurities, wherein a single impurity is less than 0.03%, and the total amount of impurities is less than 0.15%.

[0023] The lithium-magnesium metal film preparation method has the advantages that the density of the obtained lithium-magnesium metal film is only 1.21-1.26 g / cm 3 Meanwhile, the Young's modulus of the lithium-magnesium alloy is greater than or equal to 45 GPa, the high rigidity ensures that the driver provides higher sensitivity, the lithium-magnesium alloy has small thermal expansion coefficient, strong anti-aging ability, stable acoustic performance in long-term use, and controllable material processing, and the thickness can be accurately processed in the range of 0.05 mm to 0.4 mm, which is suitable for the structure requirements of various loudspeakers, the damping coefficient of the lithium-magnesium alloy is greater than or equal to 0.02, which is about 12 times of that of a conventional metal (aluminum or titanium), and the damping coefficient of the lithium-magnesium alloy is higher than that of the existing magnesium-lithium alloy diaphragm, which is more conducive to reducing the harmonic distortion of the driver and providing better sound quality. In the lithium-magnesium alloy material, the content of Ca is controlled to be 0-0.3% in a low amount, the excessive Ca is avoided to increase the brittleness of the alloy, the toughness of the material is improved, and the lithium-magnesium metal film is prevented from cracking during vibration; the content of Cd is controlled to be 0-0.5% in a low amount, the elastic modulus of the alloy is improved; 1-2% of Cu is added, Mg2Cu is formed with Mg, and the internal resistance is improved; and 0.3-0.8% of Zr is added, the grain is refined, the oxidation film bonding force is enhanced, and the damping performance is further stabilized. In step (S4), the formed film is subjected to micro-arc oxidation strengthening treatment by using a silicate electrolyte, under the action of an electric field, the silicate in the electrolyte and the metal (Li and Mg) on the surface of the formed film are subjected to an electrochemical reaction to generate a MgO-Li2O-SiO2 composite ceramic oxidation film, the hardness of the surface of the formed film is greater than or equal to 300 HV (increased by more than 40%), the internal damping coefficient is stably maintained, and the acoustic performance is further optimized.

[0024] Further, in step (S1), the vacuum melting conditions are as follows: vacuum degree is less than or equal to 5*10-3 Pa, melting temperature is 720-780 ℃, and holding time is 2-3 h; in step (S2), the surface flatness deviation of the lithium-magnesium alloy foil is less than or equal to 0.02 mm, so as to ensure the subsequent forming precision; and in step (S3), the formed film ensures that the surface of the diaphragm is flat and the size precision error is less than or equal to 0.05 mm.

[0025] Further, in step (S4), the components of the silicate electrolyte include 10-15 g / L of sodium silicate, 0.5-1 g / L of sodium hydroxide, and 0.2-0.5 g / L of sodium fluoride.

[0026] like Figures 1-4 As shown, in another typical embodiment of this application, a driver with a lithium-magnesium diaphragm 6 is provided, including sound-absorbing cotton 1, voice coil 2, phase plug 3, and a cover 4, a bracket 5, a diaphragm 6 and a magnetic circuit assembly 7 connected in sequence. The magnetic circuit assembly 7 has an annular magnetic gap 8. One end of the voice coil 2 is fixedly bonded to the side of the diaphragm 6 near the magnetic circuit assembly 7, and the other end of the voice coil 2 extends into the annular magnetic gap 8. The phase plug 3 is fixedly connected to the middle of the magnetic circuit assembly 7. The sound-absorbing cotton 1 is attached to the side of the cover 4 near the diaphragm 6. The diaphragm 6 is prepared using the lithium-magnesium metal film preparation method described above.

[0027] The driver with lithium-magnesium diaphragm 6 utilizes the low density, high rigidity, and large damping ratio of lithium-magnesium metal film to improve high-frequency response speed and reduce harmonic distortion. At the same time, it uses sound-absorbing cotton 1 to absorb reflected sound waves from the back of diaphragm 6 and the inner cavity of cover 4, reducing standing waves and noise interference caused by internal reflection and diffraction of sound waves, further reducing distortion, making the sound purer and clearer, and improving the overall acoustic quality.

[0028] Furthermore, an annular groove 9 is provided on the side of the bracket 5 that is in contact with the cover 4, and a sealing ring 10 is sandwiched between the annular groove 9 and the cover 4 to prevent air leakage and vibration from causing abnormal noise or noise.

[0029] Furthermore, the thickness of the diaphragm 6 is 0.05mm-0.4mm. Preferably, the thickness of the diaphragm 6 is 0.05mm.

[0030] Furthermore, the phase plug 3 is an aluminum alloy phase plug 3, the cover 4 is an aluminum alloy cover 4, and the voice coil 2 is a copper-clad aluminum wire voice coil 2. The aluminum alloy phase plug 3 not only adjusts the radiation direction and diffusion effect of sound waves and optimizes the propagation characteristics of high frequencies, but also has good heat dissipation performance; the aluminum alloy cover 4 serves to support and protect the internal components, while also having good heat dissipation performance, promoting the timely dissipation of heat generated during driver operation, and avoiding performance and lifespan impacts due to overheating; the copper-clad aluminum wire voice coil 2 combines the high conductivity of copper and the lightweight of aluminum, which can reduce the weight and energy consumption of the voice coil 2, improve response speed, and ensure current transmission efficiency, making the driver more sensitive.

[0031] Furthermore, the magnetic circuit assembly 7 includes a washer 71, a magnet ring 72, and a T-iron 73 that are sequentially attached. The diaphragm 6 is attached to the side of the washer 71 away from the magnet ring 72. The core of the T-iron 73 has a receiving through hole 11 in the middle. The phase plug 3 is fixedly connected to the inner wall of the receiving through hole 11.

[0032] Furthermore, the driver also includes a copper short-circuit ring 12 fixedly attached to the outer wall of the core post of the T-iron 73, and an aluminum short-circuit ring 13 fixedly attached to the outer wall of the copper short-circuit ring 12, which helps to suppress the induced eddy current of the voice coil 2, reduce the nonlinear distortion of the magnetic circuit, improve the low-frequency response and damping characteristics of the driver, and make the transient performance of the sound better.

[0033] Furthermore, the cover 4 has multiple annularly distributed mounting through holes 14, and the washer 71 has multiple screw holes 15 that correspond one-to-one with the mounting through holes 14. The cover 4 is fixedly connected to the washer 71 by screws 16, which helps to improve the connection stability between the cover 4 and the washer 71.

[0034] Furthermore, the driver also includes a dustproof mesh 17 that is attached to the side of the T-iron 73 away from the diaphragm 6 and covers the receiving through hole 11.

[0035] Furthermore, the driver also includes an annular gasket 18 that is attached to the side of the T-iron 73 away from the diaphragm 6 and communicates with the receiving through hole 11, and the dustproof net 17 is sandwiched between the annular gasket 18 and the T-iron 73.

[0036] Furthermore, the magnet ring 72 is a neodymium iron boron magnet with a remanence Br≥1.23T and coercivity Hc≥915kA / m, and the spacing of the annular magnetic gap 8 is 0.2-0.3mm.

[0037] Example 1 like Figures 1-4 As shown, a driver with a lithium-magnesium diaphragm 6 includes sound-absorbing cotton 1, a voice coil 2, a phase plug 3, and a cover 4, a bracket 5, a diaphragm 6, and a magnetic circuit assembly 7 connected in sequence. The magnetic circuit assembly 7 has an annular magnetic gap 8. One end of the voice coil 2 is fixedly bonded to the side of the diaphragm 6 near the magnetic circuit assembly 7, and the other end of the voice coil 2 extends into the annular magnetic gap 8. The phase plug 3 is fixedly connected to the middle of the magnetic circuit assembly 7. The sound-absorbing cotton 1 is attached to the side of the cover 4 near the diaphragm 6. The diaphragm 6 is a lithium-magnesium metal film.

[0038] The method for preparing the lithium-magnesium metal film includes the following steps: (S1) The raw materials are vacuum melted to obtain lithium-magnesium alloy material; (S2) The lithium-magnesium alloy material is forged at 380℃ to achieve a deformation of ≥70%, and then rolled at 280℃ with a total reduction of ≥85% to obtain a lithium-magnesium alloy foil with a thickness of 0.05mm. (S3) According to the diaphragm size specifications of the driver, the lithium magnesium alloy foil is cut, hot stamped at 220℃ and held for 2 minutes to form a molded film. (S4) Place the formed film in a silicate electrolyte and apply it at a current density of 8 A / dm³. 2 The micro-arc oxidation strengthening treatment was carried out for 18 hours, and a ceramic oxide film with a thickness of 15μm was formed on the surface of the molded film, thus obtaining the lithium magnesium metal film. The lithium-magnesium alloy material comprises the following components in percentage: 55% Li, 36.6% Mg, 2% Si, 2% C, 0.7% Al, 1% Zn, 0.1% Cd, 0.1% Ca, 0.2% Sr, 0.2% Re, 1.5% Cu, and 0.5% Zr, with the balance being impurities, each impurity being less than 0.03% and the total impurities being less than 0.15%.

[0039] In step (S1), the vacuum melting conditions are: vacuum degree of 5×10-3 Pa, melting temperature of 750℃, and holding time of 2.5h; in step (S2), the surface flatness deviation of the lithium-magnesium alloy foil is ≤0.02mm; in step (S3), the forming film ensures that the diaphragm surface is flat and the dimensional accuracy error is ≤0.05mm.

[0040] In step (S4), the silicate electrolyte comprises 12 g / L sodium silicate, 0.8 g / L sodium hydroxide, and 0.4 g / L sodium fluoride.

[0041] The bracket 5 has an annular groove 9 on the side that fits against the cover 4, and a sealing ring 10 is sandwiched between the annular groove 9 and the cover 4.

[0042] The phase plug 3 is an aluminum alloy phase plug 3, the cover 4 is an aluminum alloy cover 4, and the voice coil 2 is a copper-clad aluminum wire voice coil 2.

[0043] The magnetic circuit assembly 7 includes a washer 71, a magnet ring 72, and a T-iron 73 that are sequentially attached. The diaphragm 6 is attached to the side of the washer 71 away from the magnet ring 72. The core of the T-iron 73 has a receiving through hole 11 in the middle. The phase plug 3 is fixedly connected to the inner wall of the receiving through hole 11.

[0044] The driver also includes a copper short-circuit ring 12 fixedly attached to the outer wall of the core post of the T-iron 73, and an aluminum short-circuit ring 13 fixedly attached to the outer wall of the copper short-circuit ring 12.

[0045] The cover 4 has multiple annularly distributed mounting through holes 14, and the washer 71 has multiple screw holes 15 that correspond one-to-one with the mounting through holes 14. The cover 4 is fixedly connected to the washer 71 by screws 16.

[0046] The magnet ring 72 is a neodymium iron boron magnet with a remanence Br of 1.23T and a coercivity Hcb of 915kA / m. The spacing of the annular magnetic gap 8 is 0.25mm.

[0047] The hardness of the lithium-magnesium metal film was tested using a Vickers hardness tester (GB / T 4340.1), and the result was 320 HV. The internal damping coefficient of the lithium-magnesium metal film was determined using a metal resistance tester, and the result was 0.02.

[0048] Comparative Example 1 The commercially available speaker driver uses a titanium diaphragm. The hardness of the lithium-magnesium diaphragm was tested using a Vickers hardness tester (GB / T 4340.1), and the result was 213 HV. The internal damping coefficient of the lithium-magnesium diaphragm was determined using a metal resistance meter, and the result was 0.0016.

[0049] Frequency response and distortion testing: Using the lithium-magnesium diaphragm driver of Example 1 and the commercially available loudspeaker driver of Comparative Example 1 as samples, their sound pressure output capabilities at different frequencies were tested, and the frequency response and distortion diagrams are shown below. Figure 5 As shown in the figure, the sensitivity of Example 1 is 2-2.5 dB higher than that of Comparative Example 1, but the harmonic distortion curve of Example 1 is lower than that of Comparative Example 1, and the distortion of Example 1 is lower.

[0050] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method of producing a lithium magnesium metal film, characterized by, Includes the following steps: (S1) The raw materials are vacuum melted to obtain lithium-magnesium alloy material; (S2) The lithium-magnesium alloy material is forged at 350-400℃ to achieve a deformation of ≥70%, and then rolled at 250-300℃ with a total reduction of ≥85% to obtain a lithium-magnesium alloy foil with a thickness of 0.05mm-0.4mm. (S3) According to the diaphragm size specifications of the driver, the lithium-magnesium alloy foil is cut, hot stamped at 200-250℃ and kept warm for 1-2 minutes to form a molded film. (S4), the shaped film is placed in a silicate electrolyte to perform micro-arc oxidation strengthening treatment at a current density of 5-10 A / dm 2 for 15-20 h, a ceramic oxide film with a thickness of 10-20 μm is formed on the surface of the shaped film, and a lithium-magnesium metal film is obtained. The lithium-magnesium alloy material comprises the following components in percentage: 54.0-56.8% Li, 36.0-37.8% Mg, 2-4% Si, 2-4% C, 0-2% Al, 0-2% Zn, 0-0.5% Cd, 0-0.3% Ca, 0-0.8% Sr, 0-1% Re, 1-2% Cu, and 0.3-0.8% Zr, with the balance being impurities, each impurity being less than 0.03% and the total impurities being less than 0.15%.

2. The method of claim 1, wherein: In step (S1), the vacuum melting conditions are: vacuum degree ≤ 5×10-3Pa, melting temperature 720-780℃, and holding time 2-3h; in step (S2), the surface flatness deviation of the lithium-magnesium alloy foil is ≤ 0.02mm; in step (S3), the forming film ensures that the diaphragm surface is flat and the dimensional accuracy error is ≤ 0.05mm.

3. The method of claim 1, wherein: In step (S4), the silicate electrolyte comprises 10-15 g / L sodium silicate, 0.5-1 g / L sodium hydroxide, and 0.2-0.5 g / L sodium fluoride.

4. A driver with a lithium magnesium diaphragm, characterized by: The device includes sound-absorbing cotton, a voice coil, a phase plug, and a cover, a bracket, a diaphragm, and a magnetic circuit assembly connected in sequence. The magnetic circuit assembly has an annular magnetic gap. One end of the voice coil is fixedly bonded to the side of the diaphragm near the magnetic circuit assembly, and the other end of the voice coil extends into the annular magnetic gap. The phase plug is fixedly connected to the middle of the magnetic circuit assembly. The sound-absorbing cotton is attached to the side of the cover near the diaphragm. The diaphragm is prepared using the lithium-magnesium metal film preparation method as described in any one of claims 1-3.

5. The driver with a lithium-magnesium diaphragm according to claim 4, characterized in that: The bracket has an annular groove on the side that fits against the cover, and a sealing ring is sandwiched between the annular groove and the cover.

6. The driver with a lithium-magnesium diaphragm according to claim 4, characterized in that: The phase plug is an aluminum alloy phase plug, the cover is an aluminum alloy cover, and the voice coil is a copper-clad aluminum wire voice coil.

7. The driver with a lithium-magnesium diaphragm according to claim 4, characterized in that: The magnetic circuit assembly includes a washer, a magnet ring, and a T-iron that are sequentially attached. The diaphragm is attached to the side of the washer away from the magnet ring. The core of the T-iron has a receiving through hole in the middle, and the phase plug is fixedly connected to the inner wall of the receiving through hole.

8. The driver with a lithium-magnesium diaphragm according to claim 7, characterized in that: The driver also includes a copper short-circuit ring fixedly attached to the outer wall of the core post of the T-iron, and an aluminum short-circuit ring fixedly attached to the outer wall of the copper short-circuit ring.

9. The driver with a lithium-magnesium diaphragm according to claim 7, characterized in that: The cover has multiple annularly distributed mounting through holes, and the washer has multiple screw holes that correspond one-to-one with the mounting through holes. The cover is fixedly connected to the washer by screws.

10. The driver with a lithium-magnesium diaphragm according to claim 7, characterized in that: The magnet ring is a neodymium-iron-boron magnet with a remanence Br≥1.23T and a coercivity Hc≥915kA / m, and the distance of the annular magnetic gap is 0.2-0.3mm.

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