CN111041309B - Soluble magnesium-based alloy and preparation method thereof - Google Patents

Abstract

The invention relates to the field of metal smelting, and discloses a soluble magnesium-based alloy and a preparation method thereof. The soluble magnesium-based alloy comprises the following components by weight: Mn: 0.1-0.3%, Ca: 0.5-1.5%, Nb: 0.5-0.5% 2%, Ge: 1~3%, Si: 0.1~0.3%, Hg: 1.4~1.9%, Ga: 0.9~1.5%, Dy: 0.3~0.5%, and the rest is Mg; wherein, in the magnesium-based alloy The Ga/Hg ratio is 0.45 to 1.1. Compared with the prior art, the fracturing ball made of the magnesium-based alloy prepared by the method of the present invention has high toughness, good plasticity, strong pressure bearing capacity, and the dissolution rate in the electrolyte solution satisfies the requirement, which solves the problem of the prior art. There are problems in that the fracturing balls made of metal or non-metal materials cannot dissolve by themselves and are not easy to flow back.

Description

Soluble magnesium-based alloy and preparation method thereof

technical field

The invention relates to the field of metal smelting, in particular to a soluble magnesium-based alloy and a preparation method thereof.

Background technique

Among the newly added proven oil and gas reserves in my country in recent years, low-permeability unconventional oil and gas resources have reached 70%, and the proportion of low-permeability in my country's oil and gas production will continue to increase in the future. Low permeability unconventional oil and gas resources. The development of these unconventional oil and gas resources requires the use of multi-layer and multi-stage fracturing technology. In downhole multi-layer and multi-stage fracturing, temporary plugging tools are required to isolate the layers. After the construction is completed, such temporary plugging Tool removal.

One of the key components of the horizontal well staged fracturing technology is the fracturing ball, which is the main factor determining the success of fracturing. At present, the main problem of fracturing balls is that the fracturing balls made of metal or non-metallic materials cannot be dissolved. After the fracturing operation is completed, the fracturing balls must flow back out of the wellhead or be ground off by drilling and milling tools. The flowback or drilling and milling of the fracturing ball not only increases the complexity of the fracturing process, but also prolongs the operation time, which seriously affects the production efficiency of the fracturing operation. Especially in recent years, in order to improve the stimulation effect of oil wells, there are more and more fracturing stages in horizontal wells, more and more fracturing balls need to flow back or drill and mill after fracturing operation, and fracturing operation time is getting longer and longer. Production efficiency is getting lower and lower. The flowback or drilling and milling of the fracturing ball will greatly limit the popularization and application of the horizontal well staged fracturing technology, which is an urgent problem to be solved in the horizontal well staged fracturing technology.

Based on this, it is necessary to introduce degradable materials into such tools, so that the temporary plugging workpiece can be dissolved in the well, which can save the drilling and grinding process, which reduces the engineering risk, improves the construction efficiency, and also avoids drilling cuttings. Reservoir deals damage. Magnesium metal has active chemical properties and is easy to corrode. At the same time, its density is small and its specific strength is high. It is an ideal material for making the above workpieces.

In January 2012, Baker Hughes proposed controlled electrochemical corrosion materials (CEM-Controlled electrochemical corrosionmaterials for short) based on the electrochemical corrosion properties of magnesium alloys, and developed a dissolution rate of 10mg·cm-2·h -1 soluble sphere, and successfully used in staged fracturing of horizontal wells. In 2013, SANTROL added soluble sealing balls to its product line through research and development. When the fracturing layer has a perforated section and the layered fracturing technology needs to be adopted during the fracturing process, the soluble fracturing ball plays the role of temporarily blocking the perforations. Soluble fracturing balls can replace the standard RCN spherical fracturing balls traditionally used in oil fields. The biggest advantage of this fracturing ball is that it dissolves after effective plugging. It can be seen that the soluble fracturing ball can solve the problem of fracturing ball flowback or drilling and milling, and has the advantages of high fracturing operation efficiency and low cost, and is especially suitable for multi-stage fracturing operations in horizontal wells. However, foreign soluble fracturing ball technology is still in the stage of technical blockade, and domestic related technologies are backward, and it is still unable to efficiently realize the application of stable and high-quality fracturing balls in horizontal well staged fracturing technology. Therefore, in order to break the foreign technology blockade and promote the development and application of horizontal well staged fracturing technology in my country, it is urgent to develop high-end soluble fracturing balls for horizontal well staged fracturing technology.

SUMMARY OF THE INVENTION

Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a soluble magnesium-based alloy and a preparation method thereof. The fracturing ball made of the magnesium-based alloy prepared by the method has high toughness, good plasticity and strong pressure bearing capacity. , the dissolution rate in the electrolyte solution meets the requirements, and the problems existing in the prior art that the fracturing balls made of metal or non-metal materials cannot be dissolved by themselves and are not easy to flow back are solved.

Technical solution: The present invention provides a soluble magnesium-based alloy, comprising the following components by weight: Mn: 0.1-0.3%, Ca: 0.5-1.5%, Nb: 0.5-2%, Ge: 1-3%, Si: 0.1-0.3%, Hg: 1.4-1.9%, Ga: 0.9-1.5%, Dy: 0.3-0.5%, and the rest is Mg; wherein, the ratio of Ga/Hg in the magnesium-based alloy is 0.45-1.1.

The present invention also provides a method for preparing a soluble magnesium-based alloy, comprising the following steps: S1: taking pure metal of raw materials Mg, Mn and Nb according to the proportion and Mg-Mg-20-200 μm powder particles prepared by powder metallurgy method Ca, Mg-Si, Mg-Hg, Mg--Dy, Mg-Ge, Mg-Ga master alloys, and all raw materials are dried; S2: Melting: In a protective atmosphere, pure magnesium is first melted, and then Add pure metal of Mn and Nb at 680~720ºC, stir well and keep for 25~35min, add Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge, Mg-Ga master alloy, stir well and keep warm 25~35min, heat up to 730~740ºC; pour argon gas with a pressure of 0.12~0.5MPa and a flow rate of 0.01~0.2m ³ /min into the melt, and stir until the alloy is uniform while passing through the argon gas, and then pour the alloy into the melt. The melt temperature is reduced to 680~720ºC, and the temperature is kept for 10~20min; S3: Casting: Cast the molten metal smelted by S2 into the mold to form an ingot; S4: Homogenization heat treatment: The ingot obtained from S3 is heated at 380~420℃ After 18~30 hours of homogenization heat treatment, it is cooled with the furnace; S5: Extrusion: the ingot after homogenization heat treatment obtained in S4 is extruded into billets at 350~380 ° C, the extrusion ratio is 4~20, and the extrusion ratio is 4~20. The pressing speed is 2~20m/min; S6: aging treatment: aging treatment is performed on the blank obtained in S5; S7: machining forming: the blank obtained in S6 is machined and formed.

Preferably, in the S2, the protective atmosphere is a mixed gas of CO ₂ and SF ₆ with a ratio of 200-400:1; or, the protective atmosphere is a mixed gas of Ar and SF ₆ with a ratio of 200-400:1; or, the protective atmosphere is a mixed gas of N ₂ and SF ₆ , and the ratio is 200-400:1.

Preferably, in the S6, the temperature of the aging treatment is 100-120° C., and the time is 5-24 hours.

Preferably, in the S1, the purity of the pure metals of Mg, Mn, Cu, Ni and Ga and the Mg-Ca, Mg-Si, Mg-Hg, Mg _- Ce and FeCl master alloys are all ≥ 99.9%.

The present invention also provides a method for preparing a soluble magnesium-based alloy, which includes the following steps: S1: pulverizing: preparing the required magnesium alloy powder, mixing magnesium powder, manganese powder, niobium powder and Mg-Ca, Mg-Si, Mg -Hg, Mg-Dy, Mg-Ge, Mg-Ga master alloy powders are fully mixed according to the proportion under the protection of inert gas; S2: Pre-press: pre-press the mixed powder under the pressure of 80~120MPa; S3 : Sintering: Sinter the pre-pressed material at 520~580℃. During the sintering process, the pressure is 160~240MPa, the sintering time is 1.6~2.3h, and it is protected by inert gas. After sintering, it is cooled in the furnace to obtain solubility. Magnesium-based alloy material; S4: Machining and forming: the soluble magnesium-based alloy material is processed and formed in a sintering billet machine.

Preferably, the granularity of the magnesium powder is 50-80um, the manganese powder, niobium powder and the Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge, Mg-Ga master alloy powder The particle size is 5~10um.

Preferably, the purity of the magnesium powder, manganese powder, copper powder, nickel powder and Mg-Ca, Mg-Si, Mg-Hg, Mg-Ce, Mg-Ga, FeCl ₃ master alloy powder is all ≥99.9%.

Preferably, in the S1 and S3, the inert gas is a mixed gas of CO ₂ and SF ₆ with a ratio of 200-400:1; or, a mixed gas of Ar and SF ₆ with a ratio of 200-400 : 1; or, the mixed gas of N ₂ and SF ₆ , the ratio is 200~400:1.

The invention also provides a method for preparing a soluble magnesium-based alloy, which includes the following steps: S1: smelting the required magnesium alloy solution: in a protective atmosphere, first melting pure magnesium, adding pure metal of Mn and Nb at 700-740ºC, After stirring evenly, keep the temperature for 25~35min, add Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge, Mg-Ga master alloy, stir evenly, keep the temperature for 25~35min, 730~750ºC; Pour argon gas inside, stir until the alloy is uniform while passing argon gas, then reduce the temperature of the alloy melt to 720~730ºC, and keep the temperature for 15~20min; S2: Atomization deposition: Atomize and deposit the alloy solution in S1 , to obtain a deposition blank; the atomization pressure during the atomization deposition is 0.4~1.5MPa, the atomization gas is argon, nitrogen or carbon dioxide, and the deposition distance is 0.5~1.2m; S3: extrusion: at 350~380 ° C Extruding the deposited billet to obtain an extruded product, the extrusion ratio is 5-15, and the extrusion speed is 2-20 m/min; S4: aging treatment: aging treatment is performed on the extruded product; S5: machining forming: The aged product is machined into shape.

Preferably, in the S4, the temperature during the aging treatment is 100-120° C., and the time is 5-40 hours.

The invention also provides the application of the soluble magnesium-based alloy in the soluble alloy fracturing ball for oil and gas exploitation.

Beneficial effects: (1) In the formula of the soluble magnesium-based alloy of the present invention, the content of total alloy elements is low, the segregation is weakened during solidification, the composition is more uniform, there is no serious side reaction, and the polarization is slight.

(2) Mercury and gallium contained in the formula of the soluble magnesium-based alloy of the present invention are high hydrogen evolution overpotential elements, which can improve the electrochemical performance of the alloy, improve the stability of the magnesium alloy, inhibit the hydrogen evolution reaction, and improve the safety; The gallium is non-toxic, replaces a part of mercury, improves the working environment and improves personal safety.

(4) In the formula of the soluble magnesium-based alloy of the present invention, the main phase of the alloy is α-Mg solid solution, and the Mg ₃ Hg phase and NbCa GP area distributed in the grain boundary are composed. The mechanical properties of the alloy increase with the increase of Hg content, but There is no effect on elongation.

(5) In the preparation method of the soluble magnesium-based alloy of the present invention, the temperature of the homogenization heat treatment is 380-420° C., the time is 18-30 hours, and the furnace is cooled. The coarse as-cast eutectic Mg ₃ Hg phase is unstable. After homogenization heat treatment, the Mg ₃ Hg phase disappears and dissolves into the matrix; Clear and straight, Mg ₃ Hg phase with a size of about 0.5~1.5 μm is distributed in the matrix, which is uniformly distributed in grain boundaries and grains; Hg, Nb and Ga alloy elements have serious segregation in the as-cast state, and Hg after homogenization heat treatment , Nb and Ga are evenly distributed, and the segregation phenomenon is reduced; the homogenization heat treatment makes the coarse Mg ₃ Hg phase dissolve, so that the alloy elements are evenly distributed, and the stress concentration is weakened, which is beneficial to the subsequent plastic processing; the homogenization heat treatment can improve the corrosion resistance of the alloy. , the eutectic structure is decomposed and the number of micro-couples is reduced.

(6) The soluble magnesium-based alloy material of the present invention has a hardness of 50-70HV, a density of 1.74-2.15g/cm ³ , and a dissolution rate of 10-40 mg·cm ^-2 ·h ^-1 in a 3% KCl solution at room temperature , the dissolution rate in 3% KCl solution at about 90°C is 20-160 mg·cm ^-2 · h ^-1 , the pressure that the fracturing ball prepared in the horizontal well staged fracturing technology can withstand is 160-340 MPa, Performance is beyond the state of the art.

(7) The preparation method of the soluble magnesium-based alloy in the present invention adopts the addition of manganese, calcium, silicon and other elements to the magnesium alloy composed of magnesium, mercury and gallium elements, which can improve the strength of magnesium and also control the magnesium alloy. The dissolution rate of the magnesium alloy can achieve the synergy between the mechanical properties and the degradation rate of the magnesium alloy;

(8) The fracturing ball made of the soluble magnesium-based alloy prepared by the preparation method of the present invention has high-strength degradability and is very suitable for downhole use. The level of technology and equipment in the field of deep processing can have a strong promoting effect;

(9) The fracturing ball made of the soluble magnesium-based alloy prepared by the preparation method of the present invention can overcome the disadvantages of difficult drilling and milling, long time consumption, and difficult flowback of powder and fragments after drilling and removal during the fracturing operation of traditional materials. , greatly improve the operation efficiency and reduce the operation cost of unconventional oil and gas resource exploitation.

(10) Different methods are used according to different purposes: Method 1 (melting and casting method): The alloy in the melting and casting method has a coarse structure, uneven composition, weak mechanical properties of the alloy, and fast dissolution rate, which is suitable for working environment of 60~90 °C; Method 2 ( Powder metallurgy method): fine structure, easy to control and uniform composition, good mechanical properties, suitable for low temperature (less than 60 ℃) and high temperature (higher than 90 ℃) working environment; method three (spray deposition method): fine structure, uniform composition , good mechanical properties, lower cost than the second method, suitable for low temperature (less than 60 ℃) and high temperature (higher than 90 ℃) operating environment.

(11) Each master alloy in method 1 (melting and casting method) is prepared by powder metallurgy method, and the powder particles are 20-200 μm, which can make the composition of the melt more uniform, weaken the agglomeration of alloy elements in the melt, and help to obtain better composition. Homogeneous solid tissue. The improved composition uniformity is beneficial to both mechanical properties and electrochemical properties.

Description of drawings

Figure 1 is a photo of the soluble magnesium-based alloy prepared by the method in Embodiment 1 (upper left and upper right) and its microstructure pictures (lower left: metallographic microscope magnified 200 times, bottom right: metallographic microscope magnified 200 times) ;

FIG. 2 is a photograph (upper left and lower left) of the soluble magnesium-based alloy prepared by the method in Embodiment 4 or Embodiment 7 and its structure picture (right: magnified by a metallographic microscope at 200 times).

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings.

Embodiment 1:

This embodiment provides a soluble magnesium-based alloy for preparing fracturing balls for oil and gas development, comprising the following components by weight: Mn: 0.2%, Ca: 1%, Nb: 1%, Ge: 2%, Si: 0.2%, Hg: 1.6%, Ga: 1.0%, Dy: 0.4%, Mg: 92.6%; wherein, the Ga/Hg ratio was 0.63.

The preparation method of above-mentioned soluble magnesium-based alloy is as follows:

First, take pure metal of raw materials Mg, Mn, Nb according to the ratio and Mg-Ca, Mg-Si, Mg-Hg, Mg--Dy, Mg-Ge, Mg with powder particles of 20~200 μm prepared by powder metallurgy method -Ga master alloy, and dry all raw materials.

S1: Melting: In a mixed gas atmosphere with a ratio of CO ₂ to SF ₆ of 300:1, first melt pure magnesium, then add pure metals with a purity of ≥ 99.9% Mn and Nb at 690ºC, stir evenly, keep warm for 30 minutes, and add Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge, Mg-Ga master alloys with a purity of ≥99.9%, stir evenly, keep warm for 30 minutes, and heat up to 735ºC; 0.05m ³ /min of argon gas, stirring until the alloy is uniform while passing through argon gas, then the temperature of the alloy melt is lowered to 700ºC, and the temperature is kept for 15 minutes;

S2: Casting: The molten metal smelted by S1 is cast into a mold to form an ingot.

S3: Homogenization heat treatment: After the ingot obtained from S2 is homogenized and heat treated at 400 ° C for 25 hours, it is cooled with the furnace;

S4: Extrusion: the ingot obtained in S3 after homogenization and heat treatment is extruded into a billet at 360° C.; the extrusion ratio is 10, and the extrusion speed is 10 m/min.

S5: Aging treatment: The billet obtained in S4 was aged at 110° C. for 15 hours.

S6: Machining and forming: the blank obtained in S5 is machined and formed.

The microstructure photo of the soluble magnesium-based alloy prepared by this method is shown in Figure 1. It can be seen that the microstructure is coarse and the mechanical properties are poor.

Embodiment 2:

This embodiment is roughly the same as Embodiment 1, except that (1) in the homogenization heat treatment in S3, the temperature of the heat treatment is 380°C, and the treatment time is 30 hours; (2) the extrusion ratio in S4 extrusion is 5 ; (3) In the composition of the soluble magnesium-based alloy, Ga is 1.5%, Mg: 92.1%; among them, the Ga/Hg ratio is 0.94.

Except for this, this embodiment is exactly the same as Embodiment 1, which is not repeated here.

Embodiment 3:

This embodiment is roughly the same as Embodiment 1, except that (1) in S3 homogenization heat treatment, the heat treatment temperature is 420°C, and the treatment time is 20 hours; (2) in S4 extrusion, the extrusion ratio is 15 ; (3) In the composition of the soluble magnesium-based alloy, Hg is 1.5%; Ga is 1.5%, Mg: 92.2%; among them, the Ga/Hg ratio is 1.1.

Except for this, this embodiment is exactly the same as Embodiment 1, which is not repeated here.

The dissolution rate in the 3% KCl solution at room temperature, the dissolution rate in the 3% KCl solution at about 90°C, and the pressure parameters that the horizontal well staged fracturing ball can withstand are as follows Table 1.

Table 1

It can be seen from Table 1 that the dissolution rate in 3% KCl solution at room temperature and 90 °C is high, and the mechanical properties are good, which can meet the requirements of staged fracturing balls.

Embodiment 4:

This embodiment provides a soluble magnesium-based alloy for preparing fracturing balls for oil and gas development, comprising the following components by weight: Mn: 0.1%, Ca: 1.5%, Nb: 2%, Ge: 3%, Si: 0.2%, Hg: 1.8%, Ga: 1.44%, Dy: 0.3%, Mg: 89.96%; wherein, the Ga/Hg ratio is 0.8.

The preparation method of above-mentioned soluble magnesium-based alloy is as follows:

S1: Milling: To prepare the required magnesium alloy powder, magnesium powder with particle size of 50~80um and purity ≥99.9%, manganese powder with particle size of 5~10um and purity ≥99.9%, niobium powder and Mg-Ca, Mg- The Si, Mg-Hg, Mg-Dy, Mg-Ge, Mg-Ga master alloy powders are fully mixed under the protection of the mixed gas whose ratio of CO ₂ and SF ₆ is 300:1 according to the proportion;

S2: Pre-compression: pre-compress the mixed powder under the pressure of 100MPa;

S3: Sintering: sinter the preformed material at 560°C. During the sintering process, the pressure is 200MPa, the sintering time is 2h, and the mixed gas with the ratio of CO ₂ and SF ₆ is 300:1 for protection. After sintering Cooling with the furnace to obtain soluble magnesium-based alloy material;

S4: Machining and forming: the soluble magnesium-based alloy material is processed and formed in a sintering billet machine.

The microstructure photo of the soluble magnesium-based alloy prepared by this method is shown in Figure 2, the microstructure is refined, the non-oriented microstructure is uniform, and the properties are uniform.

Embodiment 5:

This embodiment is roughly the same as Embodiment 4, except that (1) in S3 sintering, the sintering temperature is 580°C, and the sintering time is 1.8 hours; (2) in the composition of the soluble magnesium-based alloy, Ga is 0.9%, Mg: 89.42%; wherein, the Ga/Hg ratio is 0.5.

Except for this, this embodiment is completely the same as Embodiment 4, and will not be repeated here.

Embodiment 6:

This embodiment is roughly the same as Embodiment 4, except that (1) in S3 sintering, the sintering temperature is 520°C, and the sintering time is 2.3 hours; (2) in the composition of the soluble magnesium-based alloy, Hg is 1.4%; Ga is 1.2%, Mg: 89.5%; among them, the Ga/Hg ratio is 0.86.

Except for this, this embodiment is completely the same as Embodiment 4, and will not be repeated here.

The dissolution rate in the 3% KCl solution at room temperature, the dissolution rate in the 3% KCl solution at about 90°C, and the pressure parameters that the horizontal well staged fracturing ball can withstand are as follows Table 2.

Table 2

It can be seen from Table 2 that the dissolution rate is lower than that of Table 1, because the amount of coarse second phase in the alloy is reduced, the number of microbatteries formed is reduced, and the corrosion resistance is improved. However, the mechanical properties are improved compared with those in Table 1, because the microstructure is refined and the grain-fine strengthening effect is prominent, which improves the mechanical properties of the material.

Embodiment 7:

This embodiment provides a soluble magnesium-based alloy for preparing fracturing balls for oil and gas development, comprising the following components by weight: Mn: 0.3%, Ca: 0.5%, Nb: 0.5%, Ge: 1%, Si: 0.2%, Hg: 1.5%, Ga: 1.5%, Dy: 0.5%, Mg: 94%; wherein, the Ga/Hg ratio is 1.

The preparation method of above-mentioned soluble magnesium-based alloy is as follows:

S1: Magnesium alloy solution required for smelting: In a protective atmosphere, first melt pure magnesium, then add pure metal of Mn and Nb at 720ºC, stir evenly, keep warm for 30 minutes, add Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge, Mg-Ga master alloy, stir evenly, keep warm for 30 minutes, and heat up to 740ºC; Pour argon gas into the melt, and stir until the alloy is uniform while passing argon gas, and then adjust the temperature of the alloy melt Drop to 740ºC, keep warm for 15min;

S2: Atomization deposition: The alloy solution in S1 is atomized under the condition of argon gas pressure of 1.0MPa, and then deposited under the condition of a deposition distance of 1.0m to obtain a deposited blank;

S3: Extrusion: extrude the deposited billet under the conditions that the extrusion temperature is 370°C, the extrusion ratio is 10, and the extrusion speed is 10m/min to obtain an extruded product;

S4: Aging treatment: the extruded product is subjected to aging treatment for 20 hours at a temperature of 110 °C;

S5: Machining and forming: the aging product is machined and formed.

Embodiment 8:

This embodiment is roughly the same as Embodiment 7, except that (1) in S3 extrusion, the extrusion ratio is 5; (2) in the composition of the soluble magnesium-based alloy, Hg is 1.9%, Ga is 0.9%, Mg: 93.8%; however, the Ga/Hg ratio was 0.47.

Other than that, this embodiment is completely the same as Embodiment 7, and will not be repeated here.

Embodiment 9:

This embodiment is roughly the same as Embodiment 7, except that (1) in S3 extrusion, the extrusion ratio is 15; (2) in the composition of the soluble magnesium-based alloy, Hg is 1.9%, Ga is 1.2%, Mg: 94.1%; however, the Ga/Hg ratio was 0.63.

Other than that, this embodiment is completely the same as Embodiment 7, and will not be repeated here.

The dissolution rate in the 3% KCl solution at room temperature, the dissolution rate in the 3% KCl solution at about 90°C, and the pressure parameters that the horizontal well staged fracturing ball can withstand are as follows table 3.

table 3

Dissolution rate in 3% KCl solution at room temperature (mg·cm^-2·h^-1) Dissolution rate in 3% KCl solution at about 90℃ (mg·cm^-2·h^-1) The pressure that the horizontal well staged fracturing ball can withstand (MPa) Embodiment 7 0.92 25.89 261 Embodiment 8 0.68 21.05 259 Embodiment 9 0.87 23.62 258

It can be seen from Table 3 that the mechanical properties are better than those in Table 1, and comparable to those in Table 2, because the spray deposition effectively refines the structure, and the grain-fine strengthening effect is prominent. The dissolution rate is comparable to that of Table 2 and better than that of Table 1. Because the structure is uniform and the coarse second phase that can form the microbattery is reduced, the dissolution rate is lower than that of Table 1. Alloys prepared by spray deposition may contain voids that accelerate the dissolution of the alloy, but are detrimental to mechanical properties.

The above-mentioned embodiments are only intended to illustrate the technical concept and features of the present invention, and the purpose is to enable those who are familiar with the art to understand the content of the present invention and implement it accordingly, and cannot limit the protection scope of the present invention. All equivalent transformations or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. A soluble magnesium-based alloy is characterized by comprising the following components in percentage by weight: mn: 0.1-0.3%, Ca: 0.5 to 1.5%, Nb: 0.5-2%, Ge: 1-3%, Si: 0.1-0.3%, Hg: 1.4 to 1.9%, Ga: 0.9-1.5%, Dy: 0.3-0.5% and the balance of Mg; wherein the Ga/Hg ratio in the magnesium-based alloy is 0.45-1.1.

2. A method of making a soluble magnesium based alloy as claimed in claim 1 comprising the steps of:

s1: taking pure metals of raw materials Mg, Mn and Nb according to the proportion, and intermediate alloys of Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge and Mg-Ga with powder particles of 20-200 mu m prepared by a powder metallurgy method, and drying all the raw materials;

s2: smelting: under a protective atmosphere, firstly melting pure magnesium, then adding pure metals of Mn and Nb at 680-720 ℃, and uniformly stirringThen preserving heat for 25-35 min, adding intermediate alloys of Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge and Mg-Ga, stirring uniformly, preserving heat for 25-35 min, and heating to 730-740 ℃; introducing air pressure of 0.12-0.5 MPa and flow rate of 0.01-0.2 m into the melt³Introducing argon into the alloy melt, stirring the mixture until the alloy is uniform, then cooling the alloy melt to 680-720 ℃, and preserving the temperature for 10-20 min;

s3: casting: casting the molten metal smelted in the step S2 into a mould to form a cast ingot;

s4: homogenizing heat treatment: carrying out homogenizing heat treatment on the ingot obtained in the step S3 at 380-420 ℃ for 18-30 hours, and then cooling along with the furnace;

s5: extruding: extruding the cast ingot subjected to the homogenization heat treatment obtained in the step S4 into a blank at the temperature of 350-380 ℃, wherein the extrusion ratio is 4-20, and the extrusion speed is 2-20 m/min;

s6: aging treatment: aging the blank obtained in the step S5;

s7: machining and forming: and machining and shaping the blank obtained in the step S6.

3. The soluble magnesium-based alloy according to claim 2, wherein in said S2 said protective atmosphere is CO₂And SF₆The proportion of the mixed gas is 200-400: 1;

or, the protective atmosphere is Ar and SF₆The proportion of the mixed gas is 200-400: 1;

or, the protective atmosphere is N₂And SF₆The proportion of the mixed gas is 200-400: 1.

4. a soluble magnesium-based alloy according to claim 2 or 3, wherein said aging treatment in S6 is carried out at a temperature of 100 to 120 ℃ for a period of 5 to 24 hours.

5. A method of making a soluble magnesium based alloy as claimed in claim 1 comprising the steps of:

s1: milling: preparing required magnesium alloy powder, and fully mixing magnesium powder, manganese powder, niobium powder and intermediate alloy powder of Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge and Mg-Ga according to the proportion under the protection of inert gas;

s2: pre-pressing: prepressing and forming the mixed powder under the pressure of 80-120 MPa;

s3, sintering: sintering the pre-pressed and formed material at 520-580 ℃, applying pressure of 160-240 MPa in the sintering process, sintering time of 1.6-2.3 h, introducing inert gas for protection, and cooling along with a furnace after sintering to obtain a soluble magnesium-based alloy material;

s4: machining and forming: and processing and shaping the soluble magnesium-based alloy material in a sintering blank machine.

6. The soluble magnesium-based alloy according to claim 5, wherein said magnesium powder has a particle size of 50-80 um, and said manganese powder, niobium powder and said Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge, Mg-Ga master alloy powder each have a particle size of 5-10 um.

7. The soluble magnesium-based alloy according to claim 5 or 6, wherein in said S1 and said S3, said inert gas is CO₂And SF₆The proportion of the mixed gas is 200-400: 1;

or, Ar and SF₆The proportion of the mixed gas is 200-400: 1;

or, N₂And SF₆The proportion of the mixed gas is 200-400: 1.

8. a method of making a soluble magnesium based alloy as claimed in claim 1 comprising the steps of:

s1: smelting the required magnesium alloy solution: under a protective atmosphere, firstly melting pure magnesium, then adding pure metals of Mn and Nb at 700-740 ℃, uniformly stirring, keeping the temperature for 25-35 min, adding intermediate alloys of Mg-Ca, Mg-Si, Mg-Hg, Mg-Dy, Mg-Ge and Mg-Ga, uniformly stirring, keeping the temperature for 25-35 min, and heating to 730-750 ℃; introducing argon into the melt, introducing the argon while stirring until the alloy is uniform, then reducing the temperature of the alloy melt to 720-730 ℃, and preserving the temperature for 15-20 min;

s2: atomization and deposition: atomizing the alloy solution in the S1, and depositing to obtain a deposition blank; the atomization pressure during atomization deposition is 0.4-1.5 MPa, the atomization gas is argon, nitrogen or carbon dioxide, and the deposition distance is 0.5-1.2 m;

s3: extruding: extruding the deposition blank at 350-380 ℃ to obtain an extruded product, wherein the extrusion ratio is 5-15, and the extrusion speed is 2-20 m/min;

s4: aging treatment: aging the extruded article;

s5: machining and forming: and machining and forming the aged product.

9. The soluble magnesium-based alloy according to claim 8, wherein said aging treatment in S4 is performed at a temperature of 100 to 120 ℃ for 5 to 40 hours.

10. Use of the soluble magnesium-based alloy of claim 1 in a soluble alloy fracturing ball for oil and gas recovery.

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