High-strength magnesium alloy castings, methods of making and using the same

Abstract

The application discloses a high-strength magnesium alloy casting and a preparation method and application thereof, and relates to the technical field of alloy materials, which is made of a magnesium alloy base and a reinforcing body distributed in the magnesium alloy base, and the magnesium alloy base comprises the following components in percentage by weight: Ta 0.05-0.5%, Ga 0.5-2%, Co 0.03-0.3%, Mn 0.2-0.8%, rare earth elements 2-4%, Si 0.5-3%, Sr 0.1-0.3%, Zn 0.8-1.5%, Nb 0.05-0.2%, Mo 0.03-0.1%, Hf 0.06-0.11%, and the balance is Mg and inevitable impurity elements. The high-strength magnesium alloy casting has good mechanical properties and excellent corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy materials, and particularly relates to a high-strength magnesium alloy casting and a preparation method and application thereof. BACKGROUND

[0002] As a light-weight high-strength metal material, magnesium alloy exhibits great application potential in the fields of aerospace, automobile manufacturing, electronic information, etc. With the increasing demand for global energy saving and emission reduction and the continuous development of industry, the market demand for magnesium alloy castings is increasing year by year, and the performance requirements for magnesium alloy castings are getting higher and higher, especially in terms of strength, which needs to withstand greater loads and more complex working conditions.

[0003] The strength of traditional magnesium alloy castings often cannot meet the use requirements of some high-end fields, and deformation or fracture is prone to occur when a large load is borne, which limits the further popularization and application of magnesium alloy castings. In the prior art, in order to improve the strength of magnesium alloy, the method of adding alloying elements is usually adopted, such as adding aluminum, zinc, manganese and the like. However, the effect of simply adding elements is sometimes not ideal, and if the proportions of the elements are not properly controlled, it may also adversely affect other properties of the magnesium alloy, such as reducing its plasticity and toughness. In addition, the magnesium alloy castings on the market also have technical defects such as insufficient corrosion resistance, relatively complex preparation process, low production efficiency, high cost, and are not conducive to large-scale industrial production.

[0004] In order to solve the above problems, the patent for invention with the authorization announcement number CN116043085B discloses a magnesium-based composite material, which comprises a magnesium alloy base and a reinforcing body distributed in the magnesium alloy base. The magnesium alloy base comprises the following components by weight percentage: Zn 4%-7%, Ca 0.05%-0.8%, Al 0-4%, Zr 0-1%, Ce 0-0.8%, La 0-0.8%, Y 0-0.8%, Nd 0-0.8%, Si 0-0.8%, Mn 0-1.5%, Sr 0-0.5%, Sn 0-1%, Sc 0-0.5%, Gd 0-0.8%, and the balance is Mg and unavoidable impurity elements. The magnesium-based composite material has excellent comprehensive properties of high thermal conductivity, high strength and toughness, and high modulus, and can be prepared at low cost. The application also provides a preparation method of the magnesium-based composite material and an electronic device using the magnesium-based composite material. However, the mechanical strength and corrosion resistance still need to be further improved. SUMMARY

[0005] The main purpose of the present application is to overcome the above-mentioned shortcomings, and to provide a high-strength magnesium alloy casting with good mechanical properties and excellent corrosion resistance, as well as a preparation method and application thereof.

[0006] To achieve the above object, the application provides a high-strength magnesium alloy casting, which is made of a magnesium alloy base and a reinforcing body distributed in the magnesium alloy base, wherein the magnesium alloy base comprises the following components by weight percentage: Ta 0.05-0.5%, Ga 0.5-2%, Co 0.03-0.3%, Mn 0.2-0.8%, rare earth elements 2-4%, Si 0.5-3%, Sr 0.1-0.3%, Zn 0.8-1.5%, Nb 0.05-0.2%, Mo 0.03-0.1%, Hf 0.06-0.11%, and the balance is Mg and inevitable impurity elements.

[0007] Preferably, the rare earth elements are mixed in a mass ratio of (3-5):1:1:(0.3-0.5) of Ce, Sc, Y and Er.

[0008] Preferably, the reinforcing body is mixed in a mass ratio of (1-3):(0.8-1.2):(0.5-1) of nanometer boron fiber, nanometer vanadium carbide and nanometer niobium nitride.

[0009] Preferably, the nanometer boron fiber has an average diameter of 30-100 nm and an aspect ratio of (15-20):1.

[0010] Preferably, the nanometer vanadium carbide has an average particle size of 10-60 nm, and the nanometer niobium nitride has a particle size of 50-100 nm.

[0011] Preferably, the volume percentage content of the reinforcing body is 2%-5%.

[0012] Another object of the application is to provide a preparation method of the high-strength magnesium alloy casting, which comprises the following steps:

[0013] Step S1: obtaining a magnesium alloy base melt by melting, cooling the magnesium alloy melt to 580-600℃ at a rate of 2-3℃ / s, and adding the reinforcing body; and forming a semi-solid slurry by ultrasonic vibration and spiral stirring for 18-22 minutes;

[0014] Step S2: preheating the mold to 200-250℃, injecting the semi-solid slurry into an injection chamber at a speed of 0.5-1 m / s by a screw conveying system under nitrogen protection, and performing semi-solid injection molding to obtain a casting blank after mold opening;

[0015] Step S3: sequentially performing homogenization treatment and aging strengthening treatment on the casting blank to obtain the high-strength magnesium alloy casting.

[0016] Preferably, the temperature of the melting in step S1 is 740-760℃.

[0017] Preferably, the frequency of the ultrasonic vibration in step S1 is 20 kHz, and the power is 250 W.

[0018] Preferably, the rotating speed of the spiral stirring in step S1 is 140-160 r / min.

[0019] Preferably, the injection pressure of the semi-solid injection molding in step S2 is 80-120 MPa, the pressure increasing rate is 10 MPa / s, the holding pressure is 60-80 MPa, and the holding time is 15-20 seconds.

[0020] Preferably, the temperature of the homogenization treatment in step S3 is 410-430℃, the holding time is 2 hours, and the furnace cooling is to room temperature.

[0021] Preferably, the temperature of the aging strengthening treatment in step S3 is 158-162℃, the holding time is 7-9 hours, and the air cooling is to room temperature.

[0022] Still another object of the present application is to provide an application of the high-strength magnesium alloy casting in a new energy automobile motor shell or an unmanned aerial vehicle landing gear.

[0023] Thanks to the above technical solutions, the present application has the following advantages:

[0024] (1) The preparation method of the high-strength magnesium alloy casting disclosed by the present application has the advantages of simple process, easy operation, high preparation efficiency, low dependence on equipment, and high popularization and application value.

[0025] (2) The high-strength magnesium alloy casting disclosed by the present application is made of a magnesium alloy base body and a reinforcing body distributed in the magnesium alloy base body, and the magnesium alloy base body comprises the following components by weight percentage: Ta 0.05-0.5%, Ga 0.5-2%, Co 0.03-0.3%, Mn 0.2-0.8%, rare earth elements 2-4%, Si 0.5-3%, Sr 0.1-0.3%, Zn 0.8-1.5%, Nb 0.05-0.2%, Mo 0.03-0.1%, Hf 0.06-0.11%, and the balance is Mg and inevitable impurity elements; through the mutual cooperation of the components, the mechanical properties of the prepared casting are good, and the corrosion resistance is excellent.

[0026] (3) The high-strength magnesium alloy casting disclosed by the present application has the advantages of precise proportioning and composite addition of rare earth elements (Ce, Sc, Y, and Er), which can effectively refine the grains and form stable intermetallic compounds (such as Mg 12 Ce, Mg 24Y5, etc.), which are dispersed in the crystal and the grain boundary, hinder the movement of dislocations, thereby significantly improving the yield strength and tensile strength of the alloy. Sc element is one of the key factors for improving the strength due to its strong solid solution strengthening and precipitation strengthening effect. The addition of Ta, Nb, Mo, Hf, etc. can form extremely fine dispersed phases, further improve the strength of the matrix through the dispersion strengthening mechanism, and pin the grain boundary to inhibit grain growth. Ga can reduce the stacking fault energy of the magnesium matrix and promote the activation of non-basal slip systems; Co and Mn form Co-Mn intermetallic compounds at the grain boundary to inhibit the propagation of micro-cracks, thereby solving the industry contradiction of "high strength-low plasticity".

[0027] (4) The high-strength magnesium alloy casting disclosed in the application, Mn as a traditional purifier and grain refiner, helps to remove harmful impurities and refine the grains, thereby improving the toughness of the alloy to some extent; Si and Sr form modified Mg2Si phases, and Sr can refine the morphology of Mg2Si from coarse needles to granular, which not only retains its strengthening effect, but also avoids the brittleness problem caused by traditional Si strengthening. The reinforcing body formed by mixing nano boron fibers, nano vanadium carbide (VC) and nano niobium nitride (NbN) in a specific mass ratio (1-3):(0.8-1.2):(0.5-1) and the magnesium alloy matrix form a high-efficiency composite material system; the nano boron fiber has extremely high strength and elastic modulus, can effectively bear external load, and transmit the load to the matrix through the interface to play a significant reinforcing effect; the nano VC and NbN particles further hinder the movement of dislocations through the dispersion strengthening mechanism, and synergistically act with the strengthening phase in the matrix to greatly improve the hardness and strength of the overall material. The existence of the nano reinforcing body can pin the crack tip, deflect the crack propagation path, and consume more fracture energy, thereby improving the strength while also positively contributing to the improvement of the fracture toughness of the composite material.

[0028] (5) The high-strength magnesium alloy casting disclosed in the application realizes the synchronous improvement of corrosion resistance and high strength through the triple protection of "rare earth passivation film + high melting point element stable phase + reinforcing body physical barrier"; the semi-solid injection molding method is adopted, the semi-solid interval is lower than the full melting casting temperature, and the stability of the reinforcing body is better; the flow front of the semi-solid slurry is in a laminar flow state due to the "liquid-solid coexistence" characteristics, avoiding the gas entrainment caused by turbulent flow in full melting casting, and significantly reducing the porosity and the segregation degree of heavy elements such as Ta and Hf. DETAILED DESCRIPTION

[0029] The following description is used to disclose the application so that those skilled in the art can implement the application. The preferred embodiments in the following description are only as examples, and other obvious modifications can be conceived by those skilled in the art.

[0030] Embodiment 1: A high-strength magnesium alloy casting made of a magnesium alloy base and a reinforcing body distributed in the magnesium alloy base, the magnesium alloy base comprising the following components by weight percentage: Ta 0.05%, Ga 0.5%, Co 0.03%, Mn 0.2%, rare earth elements 2%, Si 0.5%, Sr 0.1%, Zn 0.8%, Nb 0.05%, Mo 0.03%, Hf 0.06%, and the balance being Mg and inevitable impurity elements; the rare earth elements are a mixture of Ce, Sc, Y, and Er in a mass ratio of 3:1:1:0.3.

[0031] The reinforcing body is a mixture of nano-boron fibers, nano-vanadium carbide, and nano-niobium nitride in a mass ratio of 1:0.8:0.5; the average diameter of the nano-boron fibers is 30 nm, and the aspect ratio is 15:1; the average particle size of the nano-vanadium carbide is 10 nm; the particle size of the nano-niobium nitride is 50 nm; the volume percentage content of the reinforcing body is 2%.

[0032] A preparation method of the high-strength magnesium alloy casting, comprising the following steps:

[0033] Step S1: obtaining a magnesium alloy base melt by melting, cooling the magnesium alloy melt to 580℃ at a rate of 2℃ / s, and adding the reinforcing body; forming a semi-solid slurry by ultrasonic vibration and spiral stirring for 18 minutes;

[0034] Step S2: preheating the mold to 200℃, injecting the semi-solid slurry into the injection chamber at a speed of 0.5m / s by a screw conveying system under nitrogen protection, and performing semi-solid injection molding to obtain a casting blank after the mold is opened;

[0035] Step S3: sequentially performing homogenization treatment and aging strengthening treatment on the casting blank to obtain the high-strength magnesium alloy casting.

[0036] The temperature of the melting in step S1 is 740℃; the frequency of the ultrasonic vibration in step S1 is 20kHz, and the power is 250W; the rotation speed of the spiral stirring in step S1 is 140r / min; the injection pressure of the semi-solid injection molding in step S2 is 80MPa, the pressure increasing rate is 10MPa / s, the holding pressure is 60MPa, and the holding time is 15 seconds; the temperature of the homogenization treatment in step S3 is 410℃, the holding time is 2 hours, and the furnace cooling is performed to room temperature; the temperature of the aging strengthening treatment in step S3 is 158℃, the holding time is 7 hours, and the air cooling is performed to room temperature.

[0037] The high-strength magnesium alloy casting is applied in a new energy automobile motor shell or an unmanned aerial vehicle landing gear.

[0038] Embodiment 2: A high-strength magnesium alloy casting made of a magnesium alloy base and a reinforcing body distributed in the magnesium alloy base, the magnesium alloy base comprising the following components by weight percentage: Ta 0.15%, Ga 0.8%, Co 0.1%, Mn 0.4%, rare earth elements 2.5%, Si 1%, Sr 0.15%, Zn 1%, Nb 0.1%, Mo 0.05%, Hf 0.08%, and the balance being Mg and inevitable impurity elements; the rare earth elements are a mixture of Ce, Sc, Y, and Er in a mass ratio of 3.5:1:1:0.35.

[0039] The reinforcing body is a mixture of nano-boron fibers, nano-vanadium carbide, and nano-niobium nitride in a mass ratio of 1.5:0.9:0.7; the average diameter of the nano-boron fibers is 50 nm, and the aspect ratio is 17:1; the average particle size of the nano-vanadium carbide is 30 nm; the particle size of the nano-niobium nitride is 70 nm; the volume percentage content of the reinforcing body is 3%.

[0040] A preparation method of the high-strength magnesium alloy casting, comprising the following steps:

[0041] Step S1: obtaining a magnesium alloy base melt by melting, cooling the magnesium alloy melt to 585℃ at a rate of 2.3℃ / s, and adding the reinforcing body; forming a semi-solid slurry by ultrasonic vibration and spiral stirring for 19 minutes;

[0042] Step S2: preheating the mold to 220℃, injecting the semi-solid slurry into the injection chamber at a speed of 0.7m / s by a nitrogen-protected screw conveying system, and performing semi-solid injection molding to obtain a casting blank after the mold is opened;

[0043] Step S3: sequentially performing homogenization treatment and aging strengthening treatment on the casting blank to obtain the high-strength magnesium alloy casting.

[0044] The temperature of the melting in step S1 is 745℃; the frequency of the ultrasonic vibration in step S1 is 20kHz, and the power is 250W; the rotation speed of the spiral stirring in step S1 is 145r / min; the injection pressure of the semi-solid injection molding in step S2 is 90MPa, the pressure increasing rate is 10MPa / s, the holding pressure is 65MPa, and the holding time is 17 seconds; the temperature of the homogenization treatment in step S3 is 415℃, the holding time is 2 hours, and the furnace cooling is performed to room temperature; the temperature of the aging strengthening treatment in step S3 is 159℃, the holding time is 7.5 hours, and the air cooling is performed to room temperature.

[0045] The high-strength magnesium alloy casting is applied in a new energy automobile motor shell or a unmanned aerial vehicle landing gear.

[0046] Embodiment 3: A high-strength magnesium alloy casting made of a magnesium alloy base and a reinforcing body distributed in the magnesium alloy base, the magnesium alloy base comprising the following components by weight percentage: Ta 0.35%, Ga 1.3%, Co 0.15%, Mn 0.5%, rare earth elements 3%, Si 1.5%, Sr 0.2%, Zn 1.2%, Nb 0.12%, Mo 0.07%, Hf 0.09%, and the balance being Mg and inevitable impurity elements; the rare earth elements are a mixture of Ce, Sc, Y, and Er in a mass ratio of 4:1:1:0.4.

[0047] The reinforcing body is a mixture of nano-boron fibers, nano-vanadium carbide, and nano-niobium nitride in a mass ratio of 2:1:0.8; the average diameter of the nano-boron fibers is 70 nm, and the aspect ratio is 18:1; the average particle size of the nano-vanadium carbide is 40 nm; the particle size of the nano-niobium nitride is 80 nm; and the volume percentage content of the reinforcing body is 3.5%.

[0048] A preparation method of the high-strength magnesium alloy casting, comprising the following steps:

[0049] Step S1: obtaining a magnesium alloy base melt by melting, cooling the magnesium alloy melt to 590℃ at a rate of 2.5℃ / s, and adding the reinforcing body; and forming a semi-solid slurry by ultrasonic vibration and spiral stirring for 20 minutes;

[0050] Step S2: preheating the mold to 230℃, injecting the semi-solid slurry into the injection chamber at a speed of 0.8 m / s by a screw conveying system under nitrogen protection, and performing semi-solid injection molding to obtain a casting blank after the mold is opened;

[0051] Step S3: sequentially performing homogenization treatment and aging strengthening treatment on the casting blank to obtain the high-strength magnesium alloy casting.

[0052] The temperature of the melting in step S1 is 750℃; the frequency of the ultrasonic vibration in step S1 is 20 kHz, and the power is 250 W; the rotation speed of the spiral stirring in step S1 is 150 r / min; the injection pressure of the semi-solid injection molding in step S2 is 100 MPa, the pressure increasing rate is 10 MPa / s, the holding pressure is 70 MPa, and the holding time is 18 seconds; the temperature of the homogenization treatment in step S3 is 420℃, the holding time is 2 hours, and the furnace cooling is performed to room temperature; and the temperature of the aging strengthening treatment in step S3 is 160℃, the holding time is 8 hours, and the air cooling is performed to room temperature.

[0053] The high-strength magnesium alloy casting is applied in a new energy automobile motor shell or a unmanned aerial vehicle landing gear.

[0054] Embodiment 4: A high-strength magnesium alloy casting made of a magnesium alloy base and a reinforcing body distributed in the magnesium alloy base, the magnesium alloy base comprising the following components by weight percentage: Ta 0.45%, Ga 1.8%, Co 0.25%, Mn 0.7%, rare earth elements 3.5%, Si 2.5%, Sr 0.25%, Zn 1.3%, Nb 0.18%, Mo 0.09%, Hf 0.1%, and the balance being Mg and inevitable impurity elements; the rare earth elements are a mixture of Ce, Sc, Y, and Er in a mass ratio of 4.5:1:1:0.45.

[0055] The reinforcing body is a mixture of nano-boron fibers, nano-vanadium carbide, and nano-niobium nitride in a mass ratio of 2.5:1.1:0.9; the average diameter of the nano-boron fibers is 90 nm, and the aspect ratio is 19:1; the average particle size of the nano-vanadium carbide is 50 nm; the particle size of the nano-niobium nitride is 90 nm; the volume percentage content of the reinforcing body is 4.5%.

[0056] A preparation method of the high-strength magnesium alloy casting, comprising the following steps:

[0057] Step S1: obtaining a magnesium alloy base melt by melting, cooling the magnesium alloy melt to 595℃ at a rate of 2.8℃ / s, and adding the reinforcing body; forming a semi-solid slurry by ultrasonic vibration and spiral stirring for 21 minutes;

[0058] Step S2: preheating the mold to 240℃, injecting the semi-solid slurry into the injection chamber at a speed of 0.9m / s by a nitrogen-protected screw conveying system, and performing semi-solid injection molding to obtain a casting blank after the mold is opened;

[0059] Step S3: sequentially performing homogenization treatment and aging strengthening treatment on the casting blank to obtain the high-strength magnesium alloy casting.

[0060] The temperature of the melting in step S1 is 755℃; the frequency of the ultrasonic vibration in step S1 is 20kHz, and the power is 250W; the rotation speed of the spiral stirring in step S1 is 155r / min; the injection pressure of the semi-solid injection molding in step S2 is 110MPa, the pressure increasing rate is 10MPa / s, the holding pressure is 75MPa, and the holding time is 19 seconds; the temperature of the homogenization treatment in step S3 is 425℃, the holding time is 2 hours, and the furnace cooling is performed to room temperature; the temperature of the aging strengthening treatment in step S3 is 161℃, the holding time is 8.5 hours, and the air cooling is performed to room temperature.

[0061] The high-strength magnesium alloy casting is applied in a new energy automobile motor shell or a unmanned aerial vehicle landing gear.

[0062] Embodiment 5: A high-strength magnesium alloy casting made of a magnesium alloy matrix and a reinforcing body distributed in the magnesium alloy matrix, the magnesium alloy matrix comprising the following components by weight percentage: Ta 0.5%, Ga 2%, Co 0.3%, Mn 0.8%, rare earth elements 4%, Si 3%, Sr 0.3%, Zn 1.5%, Nb 0.2%, Mo 0.1%, Hf 0.11%, and the balance being Mg and inevitable impurity elements; the rare earth elements being a mixture of Ce, Sc, Y, and Er in a mass ratio of 5:1:1:0.5.

[0063] The reinforcing body is a mixture of nano-boron fibers, nano-vanadium carbide, and nano-niobium nitride in a mass ratio of 3:1.2:1; the average diameter of the nano-boron fibers is 100 nm, and the aspect ratio is 20:1; the average particle size of the nano-vanadium carbide is 60 nm; the particle size of the nano-niobium nitride is 100 nm; and the volume percentage content of the reinforcing body is 5%.

[0064] A preparation method of the high-strength magnesium alloy casting, comprising the following steps:

[0065] Step S1: obtaining a magnesium alloy matrix melt by melting, cooling the magnesium alloy melt to 600℃ at a rate of 3℃ / s, and adding the reinforcing body; forming a semi-solid slurry by ultrasonic vibration and spiral stirring for 22 minutes;

[0066] Step S2: preheating the mold to 250℃, injecting the semi-solid slurry into the injection chamber at a speed of 1m / s by a screw conveying system under nitrogen protection, and performing semi-solid injection molding to obtain a casting blank after the mold is opened;

[0067] Step S3: sequentially performing homogenization treatment and aging strengthening treatment on the casting blank to obtain the high-strength magnesium alloy casting.

[0068] The temperature of the melting in step S1 is 760℃; the frequency of the ultrasonic vibration in step S1 is 20kHz, and the power is 250W; the rotation speed of the spiral stirring in step S1 is 160r / min; the injection pressure of the semi-solid injection molding in step S2 is 120MPa, the pressure increasing rate is 10MPa / s, the holding pressure is 80MPa, and the holding time is 20 seconds; the temperature of the homogenization treatment in step S3 is 430℃, the holding time is 2 hours, and the furnace cooling is performed to room temperature; the temperature of the aging strengthening treatment in step S3 is 162℃, the holding time is 9 hours, and the air cooling is performed to room temperature.

[0069] The high-strength magnesium alloy casting is applied in a new energy automobile motor shell or a unmanned aerial vehicle landing gear.

[0070] Comparative Example 1

[0071] A high-strength magnesium alloy casting, a preparation method and application thereof are basically the same as those of example 1, except that Ta, Ga and Co are not added.

[0072] Comparative example 2

[0073] A high-strength magnesium alloy casting, a preparation method and application thereof are basically the same as those of example 1, except that Nb, Mo and Sr are not added.

[0074] In order to further illustrate the beneficial technical effects of the high-strength magnesium alloy casting involved in the embodiments of the present application, the high-strength magnesium alloy castings involved in example 1 and comparative examples 1-2 are subjected to relevant performance tests, and the test results are shown in table 1, and the test methods are as follows:

[0075] (1) Tensile properties: tested according to GB / T 228.1-2010 "Metallic materials- Tensile testing- Part 1: Method of test at room temperature", and the sample size is Φ10mmx50mm;

[0076] (2) Corrosion resistance: room temperature (25℃) immersion corrosion test is adopted, the corrosion medium is 15% NaCl solution, the corrosion sample is a round sheet-shaped magnesium alloy sample with a size of Φ15mmx3mm, and the corrosion test time is 100h. The weight loss of the sample before and after corrosion is measured, and the daily corrosion rate (mg·cm-2·d-1) of the magnesium alloy sample is calculated combined with the surface area of the sample. 2 1 ).

[0077] Table 1: Performance test results of high-strength magnesium alloy castings

[0078] Item Unit Example 1 Comparative Example 1 Comparative Example 2 Tensile strength MPa 385 325 340 Yield strength MPa 305 255 270 Elongation % 13 10 11 Corrosion rate mg-cm -2 ·d -1 ]]> 0.028 0.065 0.037

[0079] As can be seen from table 1, the high-strength magnesium alloy casting disclosed in the embodiments of the present application has better mechanical properties and more excellent corrosion resistance than the comparative product; the combined use of Ta, Ga, Co, Nb, Mo and Sr is beneficial to improving the above-mentioned properties.

[0080] The above shows and describes the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.​

Claims

1. A high-strength magnesium alloy casting, characterized by, The magnesium alloy base body comprises the following components by weight percentage: Ta 0.05-0.5%, Ga 0.5-2%, Co 0.03-0.3%, Mn 0.2-0.8%, rare earth elements 2-4%, Si 0.5-3%, Sr 0.1-0.3%, Zn 0.8-1.5%, Nb 0.05-0.2%, Mo 0.03-0.1%, Hf 0.06-0.11%, and the balance of Mg and inevitable impurity elements; the rare earth elements are mixed in a mass ratio of (3-5):1:1:(0.3-0.5) of Ce, Sc, Y and Er; the reinforcing body is mixed in a mass ratio of (1-3):(0.8-1.2):(0.5-1) of nanometer boron fiber, nanometer vanadium carbide and nanometer niobium nitride; and the volume percentage of the reinforcing body is 2%-5%.

2. The high-strength magnesium alloy casting according to claim 1, characterized by The average diameter of the nanometer boron fiber is 30-100 nm, and the length-diameter ratio is (15-20):1; the average particle size of the nanometer vanadium carbide is 10-60 nm; and the particle size of the nanometer niobium nitride is 50-100 nm.

3. A method of producing a high-strength magnesium alloy casting according to any one of claims 1 to 2, characterized by, The method comprises the following steps: In step S1, a magnesium alloy base body melt is obtained by melting, and the magnesium alloy melt is cooled to 580-600 ℃ at a rate of 2-3 ℃ / s, and the reinforcing body is added; ultrasonic vibration and spiral stirring are used for cooperative treatment for 18-22 minutes to form a semi-solid slurry; In step S2, a mold is preheated to 200-250 ℃, and the semi-solid slurry is injected into an injection chamber at a speed of 0.5-1 m / s through a screw conveying system under nitrogen protection, and semi-solid injection molding is performed, and a casting blank is obtained after the mold is opened; In step S3, the casting blank is sequentially subjected to homogenization treatment and aging strengthening treatment to obtain a high-strength magnesium alloy casting.

4. The method of producing a high-strength magnesium alloy casting according to claim 3, characterized by In step S1, the melting temperature is 740-760 ℃; in step S1, the ultrasonic vibration frequency is 20 kHz, and the power is 250 W; and in step S1, the spiral stirring speed is 140-160 r / min.

5. The method of producing a high-strength magnesium alloy casting according to claim 3, characterized by In step S2, the injection pressure of the semi-solid injection molding is 80-120 MPa, the pressure increasing rate is 10 MPa / s, the holding pressure is 60-80 MPa, and the holding time is 15-20 seconds.

6. The method of producing a high-strength magnesium alloy casting according to claim 3, characterized by In step S3, the homogenization treatment temperature is 410-430 ℃, the holding time is 2 hours, and the furnace cooling is performed to room temperature; and in step S3, the aging strengthening treatment temperature is 158-162 ℃, the holding time is 7-9 hours, and the air cooling is performed to room temperature.

7. Application of the high-strength magnesium alloy casting according to any one of claims 1-2 in a new energy automobile motor shell or a unmanned aerial vehicle landing gear.