A soluble magnesium alloy and its preparation method

Abstract

The present invention relates to a soluble magnesium alloy and a preparation method thereof. The composition of the soluble magnesium alloy is Mg a A b RE c X d Co e alloy, wherein A is any one or more of elements such as Al, Zn, Ca, Sn, Mn, Zr, etc., 0.001 wt. %

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material processing, and particularly relates to a soluble magnesium alloy and a preparation method thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Soluble metal materials have been gradually applied to the staged fracturing production process of shale oil and gas. The temporary plugging tools prepared therefrom can be naturally dissolved in the groundwater environment, avoiding the artificial removal process, and can significantly improve production efficiency and reduce costs. However, the room temperature dissolution rate of most soluble metal materials is slow, and passivation is likely to occur in an alkaline solution environment. To address this issue, a common method is to put weak acid at the position of the temporary plugging tool after the fracturing process to lower the pH value of the surrounding environment and increase the dissolution rate of related components. This method affects the oil and gas production efficiency to varying degrees due to the increase in process steps.

[0004] Magnesium alloys have the characteristics of low density, high specific strength and specific stiffness, and low standard electrode potential, and are ideal soluble metal materials. However, most soluble magnesium alloy materials have a slow dissolution rate at room temperature in a chloride ion-containing solution; in a solution with a higher pH value, their corrosion potential will increase, the corrosion current will decrease, and even passivation will occur. Therefore, it is urgent to develop soluble magnesium alloy materials with a high dissolution rate at room temperature and in an alkaline solution environment, which has important value for the shale oil and gas fracturing production process. Summary of the Invention

[0005] The purpose of the present invention is to propose a soluble magnesium alloy and a preparation method thereof in view of the deficiencies of soluble metal materials in the commonly used staged fracturing technology for existing shale oil and gas exploitation. This magnesium alloy material can dissolve at a high rate at room temperature in a chloride ion-containing solution; it can also dissolve at a relatively fast rate in an alkaline potassium chloride solution environment.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect of the present invention, a soluble magnesium alloy material is provided, and the magnesium alloy is Mg a A b RE c X d Co eAn alloy, wherein A is any one or more of Al, Zn, Ca, Sn, Mn, and Zr, 0.001 wt.% < b < 10 wt.%; RE is any one or more of Gd, Y, Nd, Ce, Sm, Er, and Yb, 0.001 wt.% < c < 20 wt.%; X is Cu and / or Ni, 0.001 wt.% < d < 5 wt.%; 0.001 wt.% < e < 5 wt.%; and a + b + c + d + e = 100%.

[0008] The soluble magnesium alloy provided by the present invention can be used to prepare soluble materials and tools through processes such as casting, heat treatment, plastic forming, and powder metallurgy.

[0009] The soluble magnesium alloy material provided by the present invention has good mechanical properties and can dissolve rapidly in an aqueous solution containing chloride ions (such as 1% KCl aqueous solution, 3% KCl aqueous solution). In addition, the dissolution rate of the material in an aqueous solution containing chloride ions at a pH value of 12 is higher than 50% of its dissolution rate in an aqueous solution with the same chloride ion concentration at a pH value of 7.

[0010] The soluble magnesium alloy provided by the present invention regulates the distribution of the second phase of the microstructure by adding Co and Cu / Ni elements, forming a primary MgCo2 phase distributed at the grain boundaries and a secondary phase containing Cu / Ni / Co in the grains. In a solution containing chloride ions, both types of cathodic phases can undergo typical galvanic corrosion with the magnesium matrix and then dissolve rapidly. In addition, compared with the Mg2Cu and Mg2Ni phases containing Cu / Ni, the MgCo2 phase has a higher standard electrode potential and is prone to pitting corrosion along the grain boundaries; the relatively large-sized MgRECo phase formed by adding rare earths will cause galvanic corrosion with a large cathode and a small anode. The above factors act synergistically, enabling the magnesium alloy to achieve a relatively fast dissolution rate in an alkaline solution containing chloride ions.

[0011] Adding elements such as Al, Zn, Ca, Sn, Mn, Zr, RE, and Gd to the alloy can improve the mechanical properties of the material. Among them, Al can improve the casting performance of the magnesium alloy; Al, Zn, Sn, and RE can enhance the strength of the magnesium alloy through solid solution strengthening or precipitation strengthening; Ca, Mn, Zr, and RE can refine the microstructure, thereby improving the strength and plasticity of the material.

[0012] In the second aspect of the present invention, a preparation method of the above-mentioned soluble magnesium alloy is provided, including:

[0013] (1) Weigh pure Mg, pure Al, pure Zn, Mg-Ca master alloy, pure Sn, Mg-Mn master alloy, Mg-Zr master alloy, Mg-RE master alloy, Mg-Cu master alloy, Mg-Ni master alloy, Mg-Co master alloy, etc. according to the composition ratio of the soluble magnesium alloy; melt and cast into a soluble magnesium alloy ingot under atmosphere protection;

[0014] (2) Heat-treat the soluble magnesium alloy ingot prepared in the previous step;

[0015] (3) Process the heat-treated soluble magnesium alloy obtained in the previous step into rods, tubes, plates, etc. by extrusion methods such as hot extrusion or rolling and forging.

[0016] (4) Perform aging treatment on the extruded material prepared in the previous step.

[0017] The specific steps for the melting and casting into an ingot are as follows: Under the protection of a CO2 + SF6 mixed gas, melt the prepared soluble magnesium alloy raw materials at 720 - 760 °C, hold for 40 - 60 min, stir for 5 - 10 min, and refine for 20 - 30 min. After refining, raise the temperature to 740 - 780 °C and let it stand for 30 - 40 min, and cast into an ingot at 700 - 740 °C.

[0018] The conditions for the heat treatment are: at 400 - 520 °C, the holding time is 1 - 96 h, and the cooling method is air cooling or water cooling.

[0019] The conditions for the extrusion are: the extrusion temperature is 300 - 500 °C, the extrusion ratio is 4 - 40, and the extrusion speed is 0.1 - 10 m / min. The extrusion methods include hot extrusion or rolling and forging.

[0020] The conditions for the aging treatment are: at 100 - 300 °C, hold for 1 - 200 h.

[0021] The volume ratio of CO2 to SF6 in the CO2 + SF6 mixed gas is 100 - 200:1.

[0022] In the third aspect of the present invention, there is provided the use of the above-mentioned soluble magnesium alloy in the preparation of soluble components for shale oil and gas exploitation.

[0023] The beneficial effects of the present invention are as follows:

[0024] (1) By means of the microalloying of Co and Cu / Ni, the distribution, types and sizes of cathodic phases in the microstructure of the soluble magnesium alloy are regulated, and the primary MgCo₂ phase distributed at the grain boundaries, the secondary phase containing Cu / Ni / Co in the grains and the MgRECo phase are obtained. The primary MgCo₂ phase distributed at the grain boundaries can promote the intergranular corrosion of the material; the secondary phases in the grains including the MgRECo phase will cause local galvanic corrosion of "large cathode and small anode". Therefore, the material of the present invention can not only dissolve rapidly in an aqueous solution containing chloride ions at room temperature, but also dissolve relatively rapidly in an alkaline aqueous solution containing chloride ions at room temperature.

[0025] (2) By alloying with elements such as Al, Zn, Ca, Sn, Mn, and Zr, the grain size and the size of the second phase are refined, and the mechanical properties of the magnesium alloy can be significantly improved. Among them, Al, Zn, and Sn can precipitate fine second phases through heat treatment; Ca, Mn, and Zr can refine the grain size of the ingot structure. The tensile strength of the soluble magnesium alloy prepared by the present invention > 200 MPa, the yield strength > 150 MPa, and the elongation > 10%. A relatively large amount of alloying elements are added in the present invention, and by reasonably setting the dosage, good mechanical properties are ensured on the basis of excellent dissolution rate.

[0026] (3) The present invention does not contain elements such as Fe, Cr, and Ti. Although the addition of the above elements to the magnesium alloy can improve the dissolution rate of the material in the aqueous solution containing chlorine, the solubility of the above elements in the magnesium and magnesium alloy melt above 650 °C is less than 0.1%, so it is easy to precipitate to the bottom of the melt during the alloy melting and standing process, resulting in composition segregation of the ingot and significantly reducing the mechanical properties. Removing elements such as Fe, Cr, and Ti in the present invention can reduce the difficulty and cost of material preparation.

[0027] (4) The soluble magnesium alloy of the present invention has low cost, simple preparation method, universality, is easy to scale up production, and has good application prospects. Description of the Drawings

[0028] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0029] Figure 1 It is a schematic diagram of the microstructure of the soluble magnesium alloy. Detailed Embodiments

[0030] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further descriptions of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0031] A soluble magnesium alloy material, the composition of which is Mg a A b RE c X d Co e alloy, wherein, A is any one or more of elements such as Al, Zn, Ca, Sn, Mn, Zr, etc., 0.001 wt.% < b < 10 wt.%; RE is any one or more of rare earth elements such as Gd, Y, Nd, Ce, Sm, Er, Yb, etc., 0.001 wt.% < c < 20 wt.%; X is Cu and / or Ni, 0.001 wt.% < d < 5 wt.%; 0.001 wt.% < e < 5 wt.%; and a + b + c + d + e = 100%.

[0032] In some embodiments, a soluble magnesium alloy material, the composition of which is Mg a A b RE c X d Co e alloy, wherein, A is any one or more of Al, Zn, Ca, Sn, Mn, Zr, 0.001 wt.% < b < 6 wt.%; RE is any one or more of Gd, Y, Nd, Ce, Sm, Er, Yb, 0.001 wt.% < c < 15 wt.%; X is Cu and / or Ni, 0.1 wt.% < d < 3 wt.%; 0.1 wt.% < e < 3 wt.%; and a + b + c + d + e = 100%.

[0033] In some embodiments, a soluble magnesium alloy material, the composition of which is Mg a A b RE c X d Co e alloy, wherein, A is any one or more of Al, Zn, Ca, Sn, Mn, Zr, 0.1 wt.% < b < 6 wt.%; RE is any one or more of Gd, Y, Nd, Ce, Sm, Er, Yb, 0.1 wt.% < c < 14 wt.%; X is Cu and / or Ni, 1.1 wt.% < d < 2 wt.%; 1.1 wt.% < e < 2 wt.%; and a + b + c + d + e = 100%.

[0034] In some embodiments, a soluble magnesium alloy material, the composition of which is Mg a A b RE c X d Co eAn alloy, wherein A is any one or more of Al, Zn, Ca, Sn, Mn, and Zr, 0.05 wt.% < b < 7 wt.%; RE is any one or more of Gd, Y, Nd, Ce, Sm, Er, and Yb, 1 wt.% < c < 13 wt.%; X is Cu and / or Ni, 0.5 wt.% < d < 1.2 wt.%; 1.2 wt.% < e < 3 wt.%; and a + b + c + d + e = 100%.

[0035] A soluble magnesium alloy material, the composition of which is Mg a A b RE c X d Co e An alloy, wherein A is Zn, 0.1 wt.% < b < 0.6 wt.%; RE is any one or two of Gd and Y, 10 wt.% < c < 14 wt.%; X is Cu and / or Ni, 1.1 wt.% < d < 2 wt.%; 1.1 wt.% < e < 2 wt.%; and a + b + c + d + e = 100%.

[0036] In some embodiments, a soluble magnesium alloy is composed of the following elements by mass percentage: Zn 0.5%, Gd 9%, Y 4%, Cu 0.6%, Ni 0.6%, Co 1.2%, and the balance is the Mg element.

[0037] The soluble magnesium alloy of the present invention regulates the distribution of the second phase in the structure by adding Co and Cu / Ni elements, forming the primary phase MgCo2 distributed at the grain boundaries and the secondary phase (MgRECo) containing Cu / Ni / Co in the grains. The two types of cathode phases and the magnesium matrix constitute the cathode and anode of electrochemical corrosion, respectively, and through intergranular corrosion and local "large cathode - small anode" intragranular galvanic corrosion, the soluble magnesium alloy can be rapidly dissolved in a neutral or alkaline aqueous solution containing chloride ions at room temperature.

[0038] Adding appropriate amounts of elements such as Al, Zn, Ca, Sn, Mn, Zr, and RE can improve the microstructure of the alloy, the morphology and distribution of the second phase, and thus obtain good mechanical properties.

[0039] By setting the dosages of the components, it is ensured that the soluble magnesium alloy can be rapidly dissolved in a neutral or alkaline aqueous solution containing chloride ions, while maintaining good mechanical properties.

[0040] The present invention also provides a preparation method of the above - mentioned soluble magnesium alloy, including:

[0041] (1) Weigh pure Mg, pure Al, pure Zn, Mg-Ca master alloy, pure Sn, Mg-Mn master alloy, Mg-Zr master alloy, Mg-RE master alloy, Mg-Cu master alloy, Mg-Ni master alloy, Mg-Co master alloy, etc. according to the composition ratio of the soluble magnesium alloy; melt and cast into a soluble magnesium alloy ingot under atmosphere protection;

[0042] (2) Heat-treat the soluble magnesium alloy ingot prepared in the previous step;

[0043] (3) Process the soluble magnesium alloy prepared in the previous step through hot extrusion or rolling, forging and other extrusion methods to form rods, tubes, plates, etc.

[0044] (4) Age-treat the extruded material prepared in the previous step.

[0045] The specific steps of the melting and casting into an ingot are as follows: Under the protection of a CO2+SF6 mixed gas, melt the prepared soluble magnesium alloy raw materials at 720-760°C, hold for 40-60 minutes, stir for 5-10 minutes, and refine for 20-30 minutes. After refining, raise the temperature to 740-780°C and let stand for 30-40 minutes, and cast into an ingot at 700-740°C.

[0046] The conditions for the heat treatment are: at 400-520°C, the holding time is 1-96 hours, and the cooling method is air cooling or water cooling.

[0047] The conditions for the extrusion are: extrusion temperature 300-500°C, extrusion ratio 4-40, extrusion speed 0.1-10 m / min.

[0048] The conditions for the age treatment are: at 100-300°C, hold for 1-200 hours.

[0049] The volume ratio of CO2 to SF6 in the CO2+SF6 mixed gas is 100-200:1.

[0050] In an embodiment of the present invention, there is provided an application of a soluble magnesium alloy and / or a preparation method of a soluble magnesium alloy in the preparation of fracturing tools for shale oil and gas exploitation.

[0051] The following will further elaborate on the present invention in detail in combination with specific embodiments. It should be noted that the specific embodiments are interpretations rather than limitations of the present invention.

[0052] Example 1 - Soluble Magnesium Alloy (As-Cast)

[0053] A soluble magnesium alloy, which is a Mg-Zn-Gd-Y-Cu-Ni-Co alloy and consists of the following elements by mass percentage: Zn 0.5%, Gd 9%, Y 4%, Cu 0.6%, Ni 0.6%, Co 1.2%, and the balance is Mg element.

[0054] Preparation process: According to the above alloy element ratio, weigh pure Mg, pure Zn, Mg-Gd master alloy, Mg-Y master alloy, Mg-Cu master alloy, Mg-Ni master alloy, and Mg-Co master alloy; under the protection of a CO2+SF6 mixed gas (volume ratio is 100:1), melt pure Mg at 740°C, and then sequentially add pure Zn, Mg-Gd master alloy, Mg-Y master alloy, Mg-Cu master alloy, Mg-Ni master alloy, and Mg-Co master alloy; at 740°C, hold for 40 - 60 min, stir for 5 - 10 min, and refine for 20 - 30 min. After refining, raise the temperature to 780°C and let it stand for 30 min, and cast into a soluble magnesium alloy ingot at 700°C.

[0055] Example 2 - Soluble magnesium alloy (extruded state)

[0056] For the ingot of Example 1, hold at 510°C for 24 h and air-cool; then remove the skin - process it into an extrusion blank; use an extruder to extrude it into a soluble magnesium alloy bar under the conditions of an extrusion temperature of 450°C, an extrusion ratio of 10, and an extrusion speed of 2 m / min.

[0057] Example 3 - Soluble magnesium alloy (aged state)

[0058] For the soluble magnesium alloy bar of Example 2, hold at 200°C for 64 h to obtain an aged soluble magnesium alloy.

[0059] Example 4 - Soluble magnesium alloy (as-cast state)

[0060] A soluble magnesium alloy, which is a Mg-Al-Sn-Mn-Gd-Cu-Co alloy and consists of the following elements by mass percentage: Al 5.5%, Sn 1%, Mn 0.5%, Gd 1%, Cu 0.5%, Co 2.0%, and the balance is Mg element.

[0061] Preparation process: Weigh pure Mg, pure Al, pure Sn, Mg-Mn master alloy, Mg-Gd master alloy, Mg-Cu master alloy, and Mg-Co master alloy according to the above alloy element ratio. Under the protection of a CO2 + SF6 mixed gas (volume ratio of 100:1), melt pure Mg at 740 °C, and then sequentially add pure Al, pure Sn, Mg-Mn master alloy, Mg-Gd master alloy, Mg-Cu master alloy, and Mg-Co master alloy. At 740 °C, hold for 45 - 60 min, stir for 5 - 10 min, and refine for 25 - 30 min. After refining, raise the temperature to 780 °C and let it stand for 30 min, and then cast into a soluble magnesium alloy ingot at 700 °C.

[0062] Example 5 - Soluble magnesium alloy (as-cast)

[0063] A soluble magnesium alloy, which is a Mg-Zn-Ca-Zr-Ce-Ni-Co alloy and consists of the following elements by mass percentage: Zn 2%, Ca 0.8%, Zr 0.6%, Ce 1%, Ni 0.8%, Co 3.0%, and the balance is Mg element.

[0064] Preparation process: Weigh pure Mg, pure Zn, Mg-Ca master alloy, Mg-Zr master alloy, Mg-Ce master alloy, Mg-Ni master alloy, and Mg-Co master alloy according to the above alloy element ratio. Under the protection of a CO2 + SF6 mixed gas (volume ratio of 100:1), melt pure Mg at 740 °C, and then sequentially add pure Zn, pure Sn, Mg-Ca master alloy, Mg-Zr master alloy, Mg-Ce master alloy, Mg-Ni master alloy, and Mg-Co master alloy. At 740 °C, hold for 45 - 50 min, stir for 8 min, and refine for 25 min. After refining, raise the temperature to 780 °C and let it stand for 30 min, and then cast into a soluble magnesium alloy ingot at 700 °C.

[0065] Comparative Example 1

[0066] A magnesium alloy, which is a Mg-Zn-Gd-Y-Cu alloy and consists of the following elements by mass percentage: Zn 0.5%, Gd 9%, Y 4%, Cu 2%, and the balance is Mg element.

[0067] Preparation process: Weigh pure Mg, pure Zn, Mg-Gd master alloy, Mg-Y master alloy, and Mg-Cu master alloy according to the above alloy element ratio. Under the protection of a CO2+SF6 mixed gas (volume ratio of 100:1), melt pure Mg at 740 °C, and then successively add pure Zn, Mg-Gd master alloy, Mg-Y master alloy, and Mg-Cu master alloy. At 740 °C, keep warm for 40 - 60 min, stir for 5 - 10 min, and refine for 20 - 30 min. After refining, raise the temperature to 780 °C and let it stand for 30 min, then cast into a magnesium alloy ingot at 700 °C.

[0068] Comparative Example 2

[0069] Keep the ingot of Comparative Example 1 at 510 °C for 24 h and cool it in air; then remove the skin - process it into an extrusion blank; use an extruder to extrude it into a magnesium alloy bar under the conditions of an extrusion temperature of 450 °C, an extrusion ratio of 10, and an extrusion speed of 2 m / min.

[0070] Comparative Example 3

[0071] Keep the magnesium alloy bar of Comparative Example 2 at 200 °C for 64 h to obtain an aged magnesium alloy.

[0072] Table 1 Room - temperature mechanical properties and dissolution properties of magnesium alloys

[0073]

[0074] Table 1 shows the mechanical properties and dissolution properties of the magnesium alloys in Examples 1 - 5 and Comparative Examples 1 - 3. Among them, the mechanical property test method is carried out in accordance with GB T 228.1 - 2010; the dissolution property is the test result in a 3% KCl aqueous solution environment at a temperature of 25 °C, neutral (pH = 7) and alkaline (pH = 12).

[0075] It can be seen by comparison that: The examples not only have good mechanical properties, but also have good room - temperature dissolution properties and dissolution properties in an alkaline environment; while the dissolution rate of the comparative examples is slower in an alkaline aqueous solution environment.

[0076] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A soluble magnesium alloy, characterized in that, The soluble magnesium alloy is Mg a A b RE c X d Co e alloy, where A is any one or more of Al, Zn, Ca, Sn, Mn, Zr, 0.001 wt.% < b < 10 wt.%; RE is any one or more of Gd, Y, Nd, Ce, Sm, Er, Yb, 0.001 wt.% < c < 20 wt.%; X is Cu and / or Ni, 0.001 wt.% < d < 5 wt.%; 0.001 wt.% < e < 5 wt.%; and a + b + c + d + e = 100%; The soluble magnesium alloy includes primary MgCo2 phases distributed at grain boundaries, secondary phases containing Cu / Ni / Co in grains, and MgRECo phases.

2. The soluble magnesium alloy according to claim 1, wherein The soluble magnesium alloy is Mg a A b RE c X d Co e alloy, where A is any one or more of Al, Zn, Ca, Sn, Mn, Zr, 0.05 wt.% < b < 7 wt.%; RE is any one or more of Gd, Y, Nd, Ce, Sm, Er, Yb, 1 wt.% < c < 13 wt.%; X is Cu and / or Ni, 0.5 wt.% < d < 1.2 wt.%; 1.2 wt.% < e < 3 wt.%; and a + b + c + d + e = 100%.

3. The soluble magnesium alloy according to claim 1, wherein The soluble magnesium alloy is composed of the following elements by mass percentage: Zn 0.5%, Gd 9%, Y 4%, Cu 0.6%, Ni 0.6%, Co 1.2%, and the balance is Mg element.

4. The preparation method of the soluble magnesium alloy according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: (1) Weigh pure Mg, pure Al, pure Zn, pure Sn, Mg-Ca master alloy, Mg-Mn master alloy, Mg-Zr master alloy, Mg-RE master alloy, Mg-Cu master alloy, Mg-Ni master alloy, and Mg-Co master alloy according to the component ratio of the soluble magnesium alloy; Melting under atmosphere protection and casting into a soluble magnesium alloy ingot; (2) Heat-treating the prepared soluble magnesium alloy ingot; (3) Processing the heat-treated soluble magnesium alloy by extrusion; (4) Aging-treating the prepared extruded material.

5. The preparation method according to claim 4, wherein, The specific steps for melting and casting into an ingot are as follows: Under the protection of a CO2 + SF6 mixed gas, melt the prepared raw materials of the soluble magnesium alloy at 720 - 760 °C, hold for 40 - 60 min, stir for 5 - 10 min, and refine for 20 - 30 min. After refining, raise the temperature to 740 - 780 °C and let it stand for 30 - 40 min, and then cast into a soluble magnesium alloy ingot at 700 - 740 °C.

6. The preparation method according to claim 4, characterized in that, The conditions for the heat treatment are: at 400 - 520 °C, the holding time is 1 - 96 h, and the cooling method is air cooling or water cooling.

7. The preparation method according to claim 4, characterized in that, The conditions for the extrusion are: the extrusion temperature is 300 - 500 °C, the extrusion ratio is 4 - 40, and the extrusion speed is 0.1 - 10 m / min.

8. The preparation method according to claim 4, characterized in that, The extrusion method includes hot extrusion.

9. The preparation method according to claim 4, characterized in that, The conditions for the aging treatment are: at 100 - 300 °C, hold for 1 - 200 h.

10. The preparation method according to claim 5, characterized in that, In the CO2 + SF6 mixed gas, the volume ratio of CO2 to SF6 is 100 - 200:

1.

11. The application of the soluble magnesium alloy as described in any one of claims 1 - 3 and / or the soluble magnesium alloy prepared by the preparation method as described in any one of claims 4 - 10 in the preparation of fracturing tools for shale oil and gas exploitation.

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