Preparation method of high-yield magnesium-zirconium intermediate alloy

Abstract

The application discloses a preparation method of high-yield magnesium-zirconium intermediate alloy, which comprises the following steps: (1) Mg-30Zr intermediate alloy raw materials are heated and remelted under the protection of tetrafluoroethane and argon gas atmosphere, and low-frequency electromagnetic stirring and pulse ultrasonic vibration are simultaneously started to homogenize the melt; (2) the size of zircon particle agglomerates in the melt is greater than 100 microns, and the multi-stage ceramic filtration system is used to remove the zircon particle agglomerates; (3) the melt is delivered to a gradient temperature control forming tank, the tank bottom is integrated with an ultrasonic vibration system and a sectional heating module, and the melt stays in the tank for 8-20 min; (4) the ultrasonic speed spinning device is used for rapid cooling and forming to form amorphous / microcrystalline strip material; (5) the amorphous / microcrystalline strip material is subjected to low-temperature high-energy ball milling to prepare composite powder with an average particle size of less than or equal to 10 microns; and (6) after the powder is preformed through cold isostatic pressing, the powder is heated in a vacuum environment and dynamically densified through a variable-diameter gradient extrusion die, and the extruded material is quenched in cold water to obtain the high-yield magnesium-zirconium intermediate alloy.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a high-yield magnesium-zirconium intermediate alloy, and belongs to the field of industrial light metal structural materials. BACKGROUND

[0002] Magnesium alloy, as a key category of lightweight materials, plays an irreplaceable role in strategic fields such as aerospace, new energy vehicles, and rail transit. Its excellent specific strength, shock absorption, and heat conduction performance make it a core material for achieving equipment weight reduction and efficiency improvement. To further improve the mechanical properties and processing performance of magnesium alloy, the addition of magnesium-zirconium intermediate alloy to introduce zirconium element has become an industrial consensus. Zirconium element can significantly refine alloy grains and greatly improve the strength and toughness of the material, and is an important means to prepare high-performance magnesium alloy.

[0003] However, the production cost of zirconium-containing magnesium alloy (such as Mg-RE-Zr alloy and Mg-Zn-Zr alloy) is significantly higher than that of other types of magnesium alloy, which seriously restricts its large-scale application. One of the core reasons for this phenomenon is that the recovery rate of zirconium element is extremely low: even if magnesium-zirconium intermediate alloy is used for alloying, the actual recovery rate of zirconium element in industrial production is usually not more than 30%. This means that a large amount of zirconium element is not effectively utilized, not only causing resource waste, but also directly increasing the production cost of the alloy.

[0004] The root cause of the low recovery rate of zirconium element can be attributed to the following points from a technical perspective:

[0005] 1. Inherent defects of the preparation process: The existing magnesium-zirconium intermediate alloy is mainly prepared by magnesium reduction method, which requires reducing potassium zirconium fluoride at a high temperature of 1100℃ or above. The high-temperature environment leads to the severe oxidation and combustion of magnesium, and the size of the generated zirconium particles is generally greater than 2μm, which is easy to agglomerate and settle in the melt, with a deposition rate of more than 60%. The actual alloying efficiency of the intermediate alloy is less than 40% under the traditional process, directly leading to the low utilization rate of zirconium element.

[0006] 2. Limitation of the physical properties of zirconium element: The solubility of zirconium in magnesium is only about 0.6wt%, and the melting point is as high as 1852℃, which is much higher than the melting temperature (680-850℃) of magnesium alloy. This makes the dissolution kinetics of zirconium particles in the magnesium melt blocked, and even if the stirring time is extended to 60min, the dissolution rate is still less than 50%, forming a significant dissolution barrier.

[0007] 3. Technical bottleneck of the alloying process: The dissolved zirconium element is easy to form a zirconium-rich core during solidification, which leads to more than 80% of the soluble zirconium concentrated in the intracrystalline core, and the content at the grain boundary is less than 0.1wt%, which further aggravates the problem of uneven element distribution and low utilization rate.

[0008] Although the solid solubility of zirconium in magnesium is low, an excess of zirconium needs to be added through an intermediate alloy in actual production to compensate for the loss during smelting. For example, when preparing a magnesium alloy containing 0.6wt% zirconium, an intermediate alloy containing 30% zirconium needs to be used to ensure that the zirconium content in the final alloy meets the standard. This design is similar to the "concentrated solution dilution" principle, which realizes precise control of trace elements through high-concentration carriers.

[0009] Currently, a large amount of magnesium-zirconium intermediate alloy is consumed in the industrial production of magnesium alloys, and zirconium is a strategic nuclear material with high price. The superposition of low recovery rate and high consumption makes the cost of Mg-RE-Zr, Mg-Zn-Zr and other alloys high. Although research shows that refining zirconium particles to below 600 nm can increase the alloying efficiency to more than 80%, the existing process is difficult to realize the large-scale production of nano-level particles stably. Therefore, it is of great significance to develop an efficient alloying method that can improve the recovery rate of zirconium element to reduce the cost of magnesium alloys containing zirconium and improve their market competitiveness. SUMMARY

[0010] The purpose of the present application is to provide a preparation method of high-yield magnesium-zirconium intermediate alloy, which solves the problems of uneven distribution of zirconium, low recovery rate and coarse second phase in the traditional process through multi-field synergistic strengthening and dynamic forming technology.

[0011] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0012] A preparation method of high-yield magnesium-zirconium intermediate alloy, comprising the following steps:

[0013] (1) Put the Mg-30Zr intermediate alloy raw material into a sealed induction furnace, heat to 820-840℃ under the protection of tetrafluoroethane and argon atmosphere, and simultaneously start the low-frequency electromagnetic stirring and pulse ultrasonic vibration to homogenize the melt;

[0014] (2) Remove the zirconium particle agglomerates with a size of >100μm in the melt through a multi-stage ceramic filtration system;

[0015] (3) Use a quantitative pump to deliver the purified melt to a gradient temperature control forming tank, the tank bottom is integrated with an ultrasonic vibration system and a segmented heating module, and the melt stays in the tank for 8-20 min;

[0016] (4) Rapidly cool and form amorphous / microcrystalline ribbons with a thickness of 50-150μm through a supersonic speed ribbon device;

[0017] (5) Low-temperature high-energy ball mill the amorphous / microcrystalline ribbons, add 0.5-1.5wt% nanometer carbon tubes as process control agents, and prepare composite powders with an average particle size of ≤10μm;

[0018] (6) The powder is pre-formed by cold isostatic pressing, heated to 380-450 DEG C under vacuum environment, and dynamic densification is carried out through a variable-diameter gradient extrusion die, the extrusion ratio is 25-40, and the extruded material is quenched in cold water to obtain high-yield magnesium-zirconium intermediate alloy.

[0019] Further, in the step (1), the frequency of the low-frequency electromagnetic stirring is 5-15 Hz, and the intensity is 0.1-0.3 T; the frequency of the pulse ultrasonic vibration is 20-40 kHz, and the power density is 0.5-1.5 W / cm 2 .

[0020] Further, in the step (2), the pore size of the multi-stage ceramic filtration system is 50-100 mu m, and the effective zirconium content in the melt after filtration is greater than or equal to 25 wt%.

[0021] Further, in the step (3), the control ultrasonic vibration frequency is 40-60 kHz, and the temperature is controlled in the range of 800-830 DEG C through a sectional heating module.

[0022] Further, the width of the gradient temperature control forming tank is 50-200 mm, the length is 100-500 mm, and the height is less than or equal to 8 mm.

[0023] Further, in the step (4), the copper roller linear velocity in the supersonic speed tape casting device is 30-50 m / s, and the cooling rate is 10 5 -10 6 K / s.

[0024] Further, in the step (5), the ball-to-material ratio of high-energy ball milling is 20:1-30:1, the rotation speed is 400-600 rpm, and the temperature is less than or equal to 50 DEG C.

[0025] Further, in the step (6), the pressure of cold isostatic pressing is 200-300 MPa.

[0026] The beneficial effects of the present application are:

[0027] 1. Through the coupling effect of electromagnetic stirring, pulse ultrasonic and gradient temperature control, the traditional process bottleneck of Zr particle agglomeration is broken, the uniformity of Zr element distribution in the magnesium matrix is greatly improved, and after ceramic sheet filtration, the original large particle Zr can be removed to avoid the formation of uncontrollable organization.

[0028] 2. The gradient temperature control forming tank designed innovatively combines the supersonic speed tape casting process to realize dynamic homogenization and rapid solidification of the melt within 8-20 min, form a nano-sized Zr dispersed distribution of amorphous / microcrystalline structure, and significantly improve the alloying efficiency.

[0029] 3. By controlling the height of the tank, even if Zr particles settle again, the fluctuation of their composition will be controlled within an effective range. Moreover, by combining an ultrasonic vibration device, the movement distance of Zr elements can be reduced, enabling rapid homogenization of the composition.

[0030] 4. Carbon nanotubes are introduced as a dynamic reaction medium during the high-energy ball milling stage, forming a three-dimensional network of nanobarriers during subsequent extrusion and dynamic recrystallization, effectively suppressing the diffusion and segregation of Zr. During the smelting process, based on the principle of microstructure inheritance, the Zr yield is increased by controlling the initial solidification conditions of the Mg-Zr master alloy. Detailed Implementation

[0031] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0032] The specific steps of the method for improving the alloying efficiency of magnesium-zirconium master alloys provided by this invention are as follows:

[0033] (1) The Mg-30Zr master alloy raw material is put into a closed induction furnace and heated to 820-840℃ for remelting under the protective atmosphere of tetrafluoroethane and argon. At the same time, low-frequency electromagnetic stirring (frequency 5-15Hz, intensity 0.1-0.3T) and pulsed ultrasonic vibration (frequency 20-40kHz, power density 0.5-1.5W / cm³) are turned on. 2 This allows the melt to achieve homogenization under the combined effect of electromagnetic force and acoustic cavitation.

[0034] (2) Subsequently, zirconium particle agglomerates with a size >100μm are removed by a multi-stage ceramic filtration system (pore size 50-100μm) to ensure that the effective zirconium content in the melt after filtration is ≥25wt%.

[0035] (3) A metering pump is used to transport the purified melt to a gradient temperature-controlled forming tank. The tank is 50-200 mm wide, 100-500 mm long, and ≤8 mm high. The bottom of the tank integrates an ultrasonic vibration system (frequency 40-60 kHz) and a segmented heating module (temperature adjustable within the range of 800-830 ℃). During the 8-20 min period when the melt stays in the tank, the ultrasonic cavitation effect continuously breaks up the agglomeration of Zr particles and promotes the uniform diffusion of Zr atoms in the magnesium matrix.

[0036] The gradient temperature control molding tank used in this invention can be equipped with an ultrasonic transducer at the bottom of its outer side and form a segmented heating module by means of resistance heating, thereby realizing ultrasonic vibration at a certain frequency and controlling the temperature to change within a certain range.

[0037] (4) Subsequently, the amorphous / microcrystalline ribbon with a thickness of 50-150 μm is formed by rapid cooling through a supersonic spinning device (copper roller linear speed of 30-50 m / s) at a cooling rate of 10 5 -10 6 K / s.

[0038] (5) The amorphous ribbon is subjected to low-temperature high-energy ball milling (ball-to-powder ratio of 20:1-30:1, rotation speed of 400-600 rpm, and temperature of ≤50°C) with the addition of 0.5-1.5 wt% of nanometer carbon tubes as a process control agent to prepare a composite powder with an average particle size of ≤10 μm.

[0039] (6) After the powder is pre-formed by cold isostatic pressing (pressure of 200-300 MPa), the powder is heated to 380-450°C in a vacuum environment and subjected to dynamic densification through a variable-diameter gradient extrusion die (extrusion ratio of 25-40), and the extruded material is quenched in cold water to obtain a high-yield magnesium-zirconium intermediate alloy.

[0040] In the following examples, the calculation method of the yield of Zr element is as follows: measured value / addition amount x 100%. Since there is a certain fluctuation in each measured value, only the lower limit value is given.

[0041] Example 1

[0042] First, the Mg-30Zr intermediate alloy raw material is put into a sealed induction furnace and remelted at 830°C under a tetrafluoroethane and argon protective atmosphere, and a low-frequency electromagnetic stirring (frequency of 10 Hz and intensity of 0.2 T) and pulse ultrasonic vibration (frequency of 30 kHz and power density of 1 W / cm 2 ). Then, the zirconium particle agglomerates with a size of >100 μm are removed through a multi-stage ceramic filtration system.

[0043] The purified melt is delivered to a gradient temperature control forming tank by using a quantitative pump, the tank has a width of 100 mm, a length of 400 mm, and a height of 8 mm. An ultrasonic vibration with a frequency of 50 kHz and a segmented heating module (controlling the temperature to change in the range of 800-830°C) are applied. During the 15 min of the melt staying in the tank, the ultrasonic cavitation effect continuously breaks the Zr particle agglomerates and promotes the uniform diffusion of Zr atoms in the magnesium matrix. Subsequently, the amorphous / microcrystalline ribbon with a thickness of 100 μm is formed by rapid cooling through a supersonic spinning device (copper roller linear speed of 40 m / s).

[0044] The amorphous ribbon was subjected to low-temperature high-energy ball milling with a ball-to-powder ratio of 25:1, a rotation speed of 500 rpm, and a temperature of 25°C. 1 wt% of nanometer carbon tubes were added as a process control agent to prepare a composite powder with an average particle size of 5 pm. After preforming the powder by cold isostatic pressing at 250 MPa, dynamic densification was performed by a variable-diameter gradient extrusion die (extrusion ratio of 30) under vacuum at a temperature of 400°C. After quenching in cold water, the Zr element yield of the obtained magnesium-zirconium intermediate alloy was ≥60%.

[0045] Example 2

[0046] First, the Mg-30Zr intermediate alloy raw material was placed in a sealed induction furnace and remelted at 820°C under a protective atmosphere of tetrafluoroethane and argon. Low-frequency electromagnetic stirring (frequency of 5 Hz and intensity of 0.1 T) and pulsed ultrasonic vibration (frequency of 20 kHz and power density of 0.5 W / cm 2 Then, the zirconium particle agglomerates with a size of >100 pm were removed through a multi-stage ceramic filtration system.

[0047] The purified melt was delivered to a gradient temperature control forming tank using a quantitative pump. The tank had a width of 50 mm, a length of 100 mm, and a height of 8 mm. An ultrasonic vibration frequency of 40 kHz and a segmented heating module (controlling the temperature to vary within a range of 800-830°C) were applied. During the 8 min residence of the melt in the tank, the ultrasonic cavitation effect continuously broke up the Zr particle agglomerates and promoted the uniform diffusion of Zr atoms in the magnesium matrix. Then, the amorphous / microcrystalline ribbon with a thickness of 50 pm was formed by rapid cooling through a supersonic spinning device (copper roller linear speed of 30 m / s).

[0048] The amorphous ribbon was subjected to low-temperature high-energy ball milling with a ball-to-powder ratio of 25:1, a rotation speed of 500 rpm, and a temperature of 25°C. 1 wt% of nanometer carbon tubes were added as a process control agent to prepare a composite powder with an average particle size of 5 pm. After preforming the powder by cold isostatic pressing at 200 MPa, dynamic densification was performed by a variable-diameter gradient extrusion die (extrusion ratio of 25) under vacuum at a temperature of 380°C. After quenching in cold water, the Zr element yield of the obtained magnesium-zirconium intermediate alloy was ≥61%.

[0049] Example 3

[0050] First, the Mg-30Zr intermediate alloy raw material was placed in a sealed induction furnace and remelted at 840°C under a protective atmosphere of tetrafluoroethane and argon. Low-frequency electromagnetic stirring (frequency of 15 Hz and intensity of 0.3 T) and pulsed ultrasonic vibration (frequency of 40 kHz and power density of 1.5 W / cm 2 Then, the zirconium particle agglomerates with a size of >100 pm were removed through a multi-stage ceramic filtration system.

[0051] The purified melt was delivered to a gradient temperature forming tank by a quantitative pump. The tank has a width of 200 mm, a length of 500 mm, and a height of 8 mm. An ultrasonic vibration with a frequency of 60 kHz was applied, and a segmented heating module was used to control the temperature in the range of 800-830°C. During the 20 min residence of the melt in the tank, the ultrasonic cavitation effect continuously broke up the Zr particle agglomerates and promoted the uniform diffusion of Zr atoms in the Mg matrix. Subsequently, the amorphous / microcrystalline ribbon with a thickness of 150 μm was formed by rapid cooling through a supersonic spinning device (copper roller linear velocity of 50 m / s).

[0052] The amorphous ribbon was subjected to low-temperature high-energy ball milling at a ball-to-powder ratio of 30:1, a rotation speed of 600 rpm, and a temperature of 50°C. 1.5 wt% of nanotubes were added as a process control agent to prepare a composite powder with an average particle size of 10 μm. After preforming the powder by cold isostatic pressing at 300 MPa, dynamic densification was performed by a variable-diameter gradient extrusion die (extrusion ratio of 40) under vacuum at a temperature of 450°C. After quenching in cold water, the Zr element yield of the obtained Mg-Zr intermediate alloy was ≥60%.

[0053] Example 4

[0054] First, the Mg-30Zr intermediate alloy raw material was placed in a sealed induction furnace and remelted at 830°C under a tetrafluoroethane and argon protective atmosphere. A low-frequency electromagnetic stirring (frequency of 10 Hz, intensity of 0.2 T) and pulsed ultrasonic vibration (frequency of 30 kHz, power density of 1 W / cm 2 ). Subsequently, the Zr particle agglomerates with a size >100 μm were removed by a multi-stage ceramic filtration system.

[0055] The purified melt was delivered to a gradient temperature forming tank by a quantitative pump. The tank has a width of 200 mm, a length of 500 mm, and a height of 8 mm. An ultrasonic vibration with a frequency of 60 kHz was applied, and a segmented heating module was used to control the temperature in the range of 800-830°C. During the 20 min residence of the melt in the tank, the ultrasonic cavitation effect continuously broke up the Zr particle agglomerates and promoted the uniform diffusion of Zr atoms in the Mg matrix. Subsequently, the amorphous / microcrystalline ribbon with a thickness of 150 μm was formed by rapid cooling through a supersonic spinning device (copper roller linear velocity of 50 m / s).

[0056] The amorphous ribbon was subjected to low-temperature high-energy ball milling at a ball-to-powder ratio of 30:1, a rotation speed of 600 rpm, and a temperature of 50°C. 1.5 wt% of nanotubes were added as a process control agent to prepare a composite powder with an average particle size of 10 μm. After preforming the powder by cold isostatic pressing at 300 MPa, dynamic densification was performed by a variable-diameter gradient extrusion die (extrusion ratio of 40) under vacuum at a temperature of 450°C. After quenching in cold water, the Zr element yield of the obtained Mg-Zr intermediate alloy was ≥60%.

[0057] Example 5

[0058] Firstly, Mg-30Zr master alloy raw materials were put into a sealed induction furnace and remelted at 825°C under a protective atmosphere of tetrafluoroethane and argon, with low-frequency electromagnetic stirring (frequency 13 Hz, intensity 0.25 T) and pulsed ultrasonic vibration (frequency 35 kHz, power density 0.9 W / cm 2 ). Then, zirconium particle agglomerates with a size > 100 pm were removed through a multi-stage ceramic filtration system.

[0059] The purified melt was delivered to a gradient temperature control forming tank using a quantitative pump, with a tank width of 130 mm, a length of 420 mm, and a height of 5 mm. An ultrasonic vibration frequency of 40 kHz and a segmented heating module (controlling the temperature to vary within the range of 800-830°C) were applied. During the 8 min residence of the melt in the tank, the ultrasonic cavitation effect continuously broke up the Zr particle agglomerates and promoted the uniform diffusion of Zr atoms in the magnesium matrix. Then, the amorphous / microcrystalline ribbon with a thickness of 50 pm was rapidly cooled and formed by a supersonic spinning device (copper roller linear speed 30 m / s).

[0060] The amorphous ribbon was subjected to low-temperature high-energy ball milling, with a ball-to-powder ratio of 25:1, a rotation speed of 500 rpm, a temperature of 25°C, and the addition of 1 wt% nanotubes as a process control agent, to prepare a composite powder with an average particle size of 5 pm. After preforming the powder by cold isostatic pressing at 200 MPa, dynamic densification was performed by heating the powder to 380°C in a vacuum environment and passing it through a variable-diameter gradient extrusion die (extrusion ratio 25). After cold water quenching of the extruded material, the Zr element yield of the magnesium-zirconium master alloy was ≥61%.

[0061] Example 6

[0062] Firstly, Mg-30Zr master alloy raw materials were put into a sealed induction furnace and remelted at 825°C under a protective atmosphere of tetrafluoroethane and argon, with low-frequency electromagnetic stirring (frequency 13 Hz, intensity 0.25 T) and pulsed ultrasonic vibration (frequency 35 kHz, power density 0.9 W / cm 2 ). Then, zirconium particle agglomerates with a size > 100 pm were removed through a multi-stage ceramic filtration system.

[0063] The purified melt was delivered to a gradient temperature forming tank by a quantitative pump. The tank has a width of 100 mm, a length of 420 mm, and a height of 5 mm. An ultrasonic vibration with a frequency of 45 kHz was applied, and a segmented heating module was used to control the temperature in the range of 800-830 °C. During the 15 min residence time of the melt in the tank, the ultrasonic cavitation effect continuously broke up the Zr particle agglomerates and promoted the uniform diffusion of Zr atoms in the Mg matrix. Subsequently, the amorphous / microcrystalline ribbon with a thickness of 60 μιη was formed by rapid cooling using a high-speed spinning device (copper roller linear velocity of 48 m / s).

[0064] The amorphous ribbon was subjected to cryogenic high-energy ball milling at a ball-to-powder ratio of 30:1, a rotation speed of 550 rpm, and a temperature of 45 °C. 1.2 wt% of carbon nanotubes were added as a process control agent to prepare a composite powder with an average particle size of 8 μιη. After preforming the powder by cold isostatic pressing at 280 MPa, dynamic densification was performed by a variable-diameter gradient extrusion die (extrusion ratio of 28) under vacuum at a temperature of 430 °C. After quenching in cold water, the Zr element yield of the obtained Mg-Zr intermediate alloy was ≥63%.

[0065] Example 7

[0066] The Mg-30Zr intermediate alloy raw material was first placed in a sealed induction furnace and remelted at 835 °C under a tetrafluoroethane and argon protective atmosphere. A low-frequency electromagnetic stirring (frequency of 15 Hz, intensity of 0.3 T) and pulsed ultrasonic vibration (frequency of 40 kHz, power density of 1.5 W / cm 2 The Zr particle agglomerates with a size > 100 μιη were removed by a multi-stage ceramic filtration system.

[0067] The purified melt was delivered to a gradient temperature forming tank by a quantitative pump. The tank has a width of 80 mm, a length of 480 mm, and a height of 8 mm. An ultrasonic vibration with a frequency of 60 kHz was applied, and a segmented heating module was used to control the temperature in the range of 800-830 °C. During the 18 min residence time of the melt in the tank, the ultrasonic cavitation effect continuously broke up the Zr particle agglomerates and promoted the uniform diffusion of Zr atoms in the Mg matrix. Subsequently, the amorphous / microcrystalline ribbon with a thickness of 150 μιη was formed by rapid cooling using a high-speed spinning device (copper roller linear velocity of 50 m / s).

[0068] The amorphous ribbon was subjected to cryogenic high-energy ball milling at a ball-to-powder ratio of 25:1, a rotation speed of 300 rpm, and a temperature of 30 °C. 1.5 wt% of carbon nanotubes were added as a process control agent to prepare a composite powder with an average particle size of 10 μιη. After preforming the powder by cold isostatic pressing at 300 MPa, dynamic densification was performed by a variable-diameter gradient extrusion die (extrusion ratio of 40) under vacuum at a temperature of 450 °C. After quenching in cold water, the Zr element yield of the obtained Mg-Zr intermediate alloy was ≥62%.

[0069] Example 8

[0070] Firstly, Mg-30Zr master alloy raw materials were put into a sealed induction furnace and remelted at 835°C under a protective atmosphere of tetrafluoroethane and argon, with low-frequency electromagnetic stirring (frequency 15 Hz, intensity 0.3 T) and pulsed ultrasonic vibration (frequency 40 kHz, power density 1.5 W / cm 2 ). Then, zirconium particle agglomerates with a size > 100 μm were removed through a multi-stage ceramic filtration system.

[0071] The purified melt was delivered to a gradient temperature control forming tank using a quantitative pump, with a tank width of 80 mm, a length of 480 mm, and a height of 6 mm. An ultrasonic vibration frequency of 60 kHz and a segmented heating module (controlling the temperature to vary within the range of 800-830°C) were applied. During the 18 min residence of the melt in the tank, the ultrasonic cavitation effect continuously broke up the Zr particle agglomerates and promoted the uniform diffusion of Zr atoms in the magnesium matrix. Then, the amorphous / microcrystalline ribbon with a thickness of 150 μm was rapidly cooled and formed by a supersonic spinning device (copper roller linear speed 50 m / s).

[0072] The amorphous ribbon was subjected to low-temperature high-energy ball milling, with a ball-to-powder ratio of 27:1, a rotation speed of 350 rpm, a temperature of 30°C, and the addition of 1.5 wt% nanometer carbon tubes as a process control agent, to prepare a composite powder with an average particle size of 10 μm. After preforming the powder by cold isostatic pressing at 300 MPa, dynamic densification was performed by a variable-diameter gradient extrusion die (extrusion ratio 30) under vacuum heating to 400°C. After cold water quenching of the extruded material, the Zr element yield of the magnesium-zirconium master alloy was ≥62%.

[0073] Example 9

[0074] Firstly, Mg-30Zr master alloy raw materials were put into a sealed induction furnace and remelted at 830°C under a protective atmosphere of tetrafluoroethane and argon, with low-frequency electromagnetic stirring (frequency 7.5 Hz, intensity 0.2 T) and pulsed ultrasonic vibration (frequency 40 kHz, power density 1.5 W / cm 2 ). Then, zirconium particle agglomerates with a size > 100 μm were removed through a multi-stage ceramic filtration system.

[0075] The purified melt was delivered to a gradient temperature forming tank by a quantitative pump. The tank has a width of 50 mm, a length of 100 mm, and a height of 8 mm. An ultrasonic vibration with a frequency of 40 kHz was applied, and a segmented heating module was used to control the temperature in the range of 800-830 °C. During the 8 min residence of the melt in the tank, the ultrasonic cavitation effect continuously broke the Zr particle agglomerates and promoted the uniform diffusion of Zr atoms in the Mg matrix. Subsequently, the amorphous / microcrystalline ribbon with a thickness of 50 μm was formed by rapid cooling through a supersonic spinning device (copper roller linear velocity of 30 m / s).

[0076] The amorphous ribbon was subjected to low-temperature high-energy ball milling at a ball-to-powder ratio of 30:1, a rotation speed of 600 rpm, and a temperature of 50 °C. 1.5 wt% of carbon nanotubes were added as a process control agent to prepare a composite powder with an average particle size of 10 μm. After preforming the powder by cold isostatic pressing at 280 MPa, dynamic densification was performed by a variable-diameter gradient extrusion die (extrusion ratio of 30) under vacuum at a temperature of 450 °C. After the extruded material was quenched in cold water, the Zr element yield of the obtained Mg-Zr intermediate alloy was ≥63%.

[0077] Example 10

[0078] The Mg-30Zr intermediate alloy raw material was first placed in a sealed induction furnace and remelted at 835 °C under a tetrafluoroethane and argon protective atmosphere. At the same time, low-frequency electromagnetic stirring (frequency of 6.5 Hz and intensity of 0.26 T) and pulsed ultrasonic vibration (frequency of 25.5 kHz and power density of 1.5 W / cm 2 The Zr particle agglomerates with a size of >100 μm were removed by a multi-stage ceramic filtration system.

[0079] The purified melt was delivered to a gradient temperature forming tank by a quantitative pump. The tank has a width of 50 mm, a length of 100 mm, and a height of 8 mm. An ultrasonic vibration with a frequency of 40 kHz was applied, and a segmented heating module was used to control the temperature in the range of 800-830 °C. During the 8 min residence of the melt in the tank, the ultrasonic cavitation effect continuously broke the Zr particle agglomerates and promoted the uniform diffusion of Zr atoms in the Mg matrix. Subsequently, the amorphous / microcrystalline ribbon with a thickness of 50 μm was formed by rapid cooling through a supersonic spinning device (copper roller linear velocity of 30 m / s).

[0080] The amorphous strip was ball milled at low temperature and high energy, with a ball-to-material ratio of 27:1, a rotation speed of 350 rpm, and a temperature of 30 ℃. 1.5 wt% of carbon nanotubes were added as a process control agent. The average particle size of the composite powder was 10 μm. After cold isostatic pressing at 275 MPa, the powder was heated to 440 ℃ in a vacuum environment, and dynamic densification was performed by a variable-diameter gradient extrusion die (extrusion ratio of 28). After cold water quenching, the Zr element yield of the magnesium-zirconium intermediate alloy was ≥62%.

Claims

1. A method for producing high yield magnesium zirconium master alloy, characterized by, The method comprises the following steps: (1) Put the Mg-30Zr intermediate alloy raw material into a sealed induction furnace, heat to 820-840℃ under the protection of tetrafluoroethane and argon atmosphere, and simultaneously open the low-frequency electromagnetic stirring and pulse ultrasonic vibration to homogenize the melt; (2) Remove the zirconium particle agglomerates with size >100μm in the melt through a multi-stage ceramic filtration system; (3) Use a quantitative pump to deliver the purified melt to a gradient temperature control forming tank, integrate an ultrasonic vibration system and a segmented heating module at the bottom of the tank, and make the melt stay in the tank for 8-20min; (4) Form amorphous / microcrystalline ribbons with a thickness of 50-150μm through supersonic speed ribbon casting device rapid cooling forming; (5) Add 0.5-1.5wt% nanometer carbon tubes as process control agents to prepare composite powders with an average particle size ≤10μm through low-temperature high-energy ball milling of amorphous / microcrystalline ribbons; (6) After preforming the powders through cold isostatic pressing, heat to 380-450℃ in a vacuum environment, and perform dynamic densification through a variable-diameter gradient extrusion die with an extrusion ratio of 25-40, and quench the extruded material in cold water to obtain high-yield Mg-Zr intermediate alloy.

2. The method of producing high yield magnesium zirconium master alloy according to claim 1, characterized in that, In the step (1), the frequency of the low-frequency electromagnetic stirring is 5-15 Hz, and the intensity is 0.1-0.3 T; the frequency of the pulse ultrasonic vibration is 20-40 kHz, and the power density is 0.5-1.5 W / cm 2 .

3. The method of claim 1, wherein the high yield magnesium zirconium master alloy is prepared by the steps of: melting a magnesium alloy and a zirconium alloy in a vacuum induction furnace; and adding a rare earth element to the molten magnesium alloy and the molten zirconium alloy. In the step (2), the pore size of the multi-stage ceramic filtration system is 50-100μm, and the effective zirconium content in the filtered melt is ≥25wt%.

4. The method of claim 1, wherein the high yield magnesium zirconium master alloy is prepared by the steps of: In the step (3), the ultrasonic vibration frequency is controlled at 40-60kHz, and the temperature is controlled in the range of 800-830℃ through the segmented heating module. ​ 5. The method of producing high yield magnesium zirconium master alloy according to claim 4, characterized in that, The width of the tank body of the gradient temperature control forming tank is 50-200mm, the length is 100-500mm, and the height is ≤8mm.

6. The method of claim 1, wherein the high yield magnesium zirconium master alloy is prepared by the steps of: melting a magnesium alloy and a zirconium alloy in a vacuum induction furnace; and adding a rare earth element to the molten magnesium alloy and the molten zirconium alloy. In the step (4), the linear velocity of the copper roller in the supersonic spinning device is 30-50 m / s, and the cooling rate is 10 5 -10 6 K / s.

7. The method of claim 1, wherein the high yield magnesium zirconium master alloy is prepared by the steps of: melting a magnesium alloy and a zirconium alloy in a vacuum induction furnace; and adding a rare earth element to the molten magnesium alloy and the molten zirconium alloy. In the step (5), the ball-to-material ratio of high-energy ball milling is 20:1-30:1, the rotation speed is 400-600rpm, and the temperature is ≤50℃.

8. The method of producing high yield magnesium zirconium master alloy according to claim 1, characterized in that, In the step (6), the pressure of cold isostatic pressing is 200-300MPa.