A lightweight magnesium alloy automobile wheel hub

Abstract

The invention discloses a light magnesium alloy automobile wheel hub, the raw materials of which include pure magnesium, pure zinc, magnesium-zirconium master alloy, magnesium-antimony master alloy, magnesium-cerium master alloy, magnesium-manganese-lanthanum alloy and modified boron carbide; the magnesium-zirconium master alloy is a Mg-30wt.%Zr master alloy, the magnesium-antimony master alloy is a Mg-10wt.%Sb master alloy, the magnesium-cerium master alloy is a Mg-20wt.%Ce master alloy, the magnesium-manganese-lanthanum alloy is a Mg 96 Mn3La1 alloy. The magnesium alloy comprises, by weight, 3% to 5% Zn, 0.8% to 1.0% Zr, 0.3% to 0.7% Sb, 3% to 6% Ce, 0.6% to 0.9% Mn, 0.2% to 0.3% La, 0.3% to 0.4% modified boron carbide, and the remainder Mg. The magnesium alloy prepared using the method of the present invention exhibits high tensile strength, excellent mechanical properties, and is less susceptible to deformation and cracking during use, reducing repair and maintenance costs.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium alloy materials, in particular to a lightweight magnesium alloy automobile wheel hub. Background Art

[0002] Lightweighting vehicles has long been a development trend for automakers, with lightweighting of wheels being a particular priority. As the lightest engineering structural metal material, magnesium alloy can reduce overall vehicle weight, effectively improving fuel efficiency and reducing environmental pollution. Amidst the trend toward energy conservation and emission reduction, magnesium alloy wheels meet today's demands for lightweight and environmentally friendly vehicles, gaining market favor. Their use in high-end models has become a trend. Currently, magnesium alloy wheels are used in high-end models from Porsche, Ferrari, Bugatti, and other brands.

[0003] Magnesium alloys have many advantages, such as low density, light weight, and high specific strength. However, factors such as poor corrosion resistance, relatively low strength, and relatively poor creep resistance at high temperatures limit their application in the engineering field. There are four common strengthening methods for magnesium alloys, namely fine grain strengthening, precipitation strengthening, dispersion strengthening, and solid solution strengthening. Among them, fine grain strengthening has two advantages. In addition to improving the strength of the material, it can also improve the toughness of the material, and the reduction of grain size also directly affects the strength of the material; precipitation strengthening is also called precipitation strengthening. Its inherent influencing factor is the second phase. Since the second phase particles can generate stress fields and can also interact with dislocations to achieve the requirements of improving the strength of the alloy, the quality of the strengthening effect mainly depends on the orientation relationship, morphology characteristics and distribution state of the precipitated phase. Summary of the Invention

[0004] To this end, the present invention provides a lightweight magnesium alloy automobile wheel hub, the raw materials of which include pure magnesium, pure zinc, magnesium-zirconium master alloy, magnesium-antimony master alloy, magnesium-cerium master alloy, magnesium-manganese-lanthanum alloy and modified boron carbide; the preparation method of the modified boron carbide is as follows:

[0005] Step 1, polyvinyl alcohol and boric acid are mixed to form a mixture, the mixture is heated to 200±5°C and kept warm for 50-60 minutes, and then heated to 250±5°C and kept warm for 80-100 minutes after the end of the heat preservation, and then heated to 750±10°C and kept warm for 120-150 minutes after the end of the heat preservation, and then air-cooled to room temperature, and heated again to 1450±10°C in an argon atmosphere, kept warm for 2-3 hours, and then air-cooled to room temperature to obtain a product powder, the product powder is wet-ball milled, the slurry is passed through a 1500 mesh sieve, the sieved slurry is dried to obtain boron carbide powder;

[0006] Step 2: preparing a mixed solution of lead dichloride, tin dichloride, and hydrochloric acid, and keeping the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid constant temperature at 60±2° C. in a water bath, then soaking the boron carbide powder in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid for 30 to 40 minutes, separating the solid and the liquid, washing the solid phase with deionized water to remove the residual mixed solution, and drying to obtain an activated powder;

[0007] Step 3, prepare a mixed solution of copper sulfate, potassium sodium tartrate, sodium hypophosphite, polyvinylpyrrolidone, nickel sulfate, disodium ethylenediaminetetraacetic acid, sodium diphenylamine sulfonate and formaldehyde as a plating solution, keep the plating solution in a water bath at a constant temperature of 65±5°C, then add the activated powder to the plating solution to obtain a mixed solution, stir the mixed solution at a constant temperature of 65±5°C, add sodium hydroxide solution to the mixed solution during the stirring process to adjust the pH of the mixed solution to 13, then keep the mixture warm and stir for 30 to 40 minutes, and add the sodium hydroxide solution every five minutes during the insulation process to adjust the pH of the mixed solution to 13; after the insulation is completed, air cool to room temperature, separate the solid and liquid, wash the solid phase with deionized water to remove the residual plating solution, and dry to obtain the modified boron carbide.

[0008] Furthermore, the mass ratio of the polyvinyl alcohol and boric acid is polyvinyl alcohol:boric acid=3-4:1; in the wet ball milling, the material-ball ratio is material:ball:water=1:1.8:1; the ball milling is carried out in a planetary ball mill for 7-8 hours at a rotation speed of 100 r / min.

[0009] Furthermore, in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid, the concentration of lead dichloride is 0.4-0.5 g / L, the concentration of tin dichloride is 23-28 g / L, the mass percentage of hydrogen chloride is 2%-3%, and the solvent is water; the solid-liquid mass ratio of the boron carbide powder immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is solid / liquid = 1:50.

[0010] Furthermore, in the plating solution, the concentration of copper sulfate is 6-8 g / L, the concentration of potassium sodium tartrate is 10-14 g / L, the concentration of sodium hypophosphite is 20-22 g / L, the concentration of polyvinyl pyrrolidone is 20-25 mg / L, the concentration of nickel sulfate is 1-2 g / L, the concentration of disodium ethylenediaminetetraacetic acid is 15-18 g / L, the concentration of sodium diphenylamine sulfonate is 30-40 mg / L, the mass percentage of formaldehyde is 25%, and the solvent is water; the activated powder is added to the plating solution at a solid-liquid mass ratio of solid / liquid = 1:50; the concentration of sodium hydroxide in the sodium hydroxide solution is 1 mol / L, and the solvent is water.

[0011] Furthermore, the magnesium-zirconium master alloy is a Mg-30wt.% Zr master alloy, the magnesium-antimony master alloy is a Mg-10wt.% Sb master alloy, the magnesium-cerium master alloy is a Mg-20wt.% Ce master alloy, and the magnesium-manganese-lanthanum alloy is a Mg 96 Mn3La1 alloy.

[0012] Furthermore, the magnesium alloy comprises the following elements by weight: Zn 3% to 5%, Zr 0.8% to 1.0%, Sb 0.3% to 0.7%, Ce 3% to 6%, Mn 0.6% to 0.9%, La 0.2% to 0.3%, modified boron carbide 0.3% to 0.4%, and the remainder is Mg.

[0013] The preparation method of the above-mentioned lightweight magnesium alloy automobile wheel hub is as follows:

[0014] (1) Weighing each raw material according to the weight percentage, and polishing the surface of each raw material with sandpaper to remove the oxide scale; placing the pure magnesium in a crucible and heating it to 500° C., introducing a protective gas so that the smelting is carried out in a protective gas environment, continuing to heat the pure magnesium until it melts to obtain a melt, and after the melt is heated to 690-700° C., adding the pure zinc to the melt, keeping the temperature so that the pure zinc is completely melted, and then heating it to 730-740° C., and adding the magnesium-antimony master alloy and the magnesium-cerium master alloy to the melt. After the magnesium-antimony master alloy and the magnesium-cerium master alloy are melted into the melt, the temperature is raised to 780-785° C. and maintained, the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are added to the melt, the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are melted into the melt, and the melt is stirred for 30-40 minutes to mix, a refining agent is added to the melt for refining, and the temperature is then lowered to 720-725° C. to skim off the slag, and modified boron carbide is added. The melt is stirred for 10 minutes and then immediately cast into a mold cavity to obtain a magnesium alloy billet;

[0015] (2) heating the magnesium alloy billet to 520±5° C. and keeping the temperature for 12 to 13 hours, then quenching the billet with water to room temperature, and then extruding the billet in an extrusion die to obtain an extruded billet;

[0016] (3) placing the extruded billet at 200-220° C. for aging for 100-120 h, then air-cooling it to room temperature, grinding it to remove surface oxide scale, and cutting it into the automobile wheel hub.

[0017] Furthermore, the protective gas is a mixture of carbon dioxide and sulfur hexafluoride, and the volume ratio of the carbon dioxide and sulfur hexafluoride is carbon dioxide:sulfur hexafluoride=99:1.

[0018] Furthermore, the extrusion deformation process parameters are: extrusion temperature is 420-430° C., extrusion speed is set to 25-30 mm / min, and extrusion ratio is 12.

[0019] The technical principle of the present invention is as follows: By introducing boron carbide nanoparticles into the magnesium alloy, the nanoparticles are mainly distributed along the grain boundaries in the magnesium matrix after forming. After the boron carbide is modified, the wettability of the boron carbide in the melt is significantly improved, and the bonding strength between the boron carbide nanoparticles and the magnesium matrix is ​​enhanced, so that the nanoparticles located at the grain boundaries can be firmly pinned to the matrix grain boundaries. On the one hand, it is not easy to form microcracks at the grain boundaries, and on the other hand, it can prevent the growth of matrix grains. At the same time, the boron carbide particles provide sites for the non-uniform nucleation of the magnesium alloy, increasing the nucleation rate and achieving the effect of fine grain strengthening. By adding a magnesium-manganese-lanthanum alloy, a composite precipitate phase of α-manganese and rare earth is formed in the magnesium alloy, which has a second phase strengthening effect on the magnesium alloy, thereby further improving the strength of the magnesium alloy.

[0020] The beneficial effects of the present invention are that the magnesium alloy prepared by the method of the present invention has high tensile strength, exhibits good mechanical properties, is not prone to deformation and cracking during use, and reduces repair and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure is a comparison chart of the tensile strength of the magnesium alloy materials prepared by the methods described in each embodiment and comparative example. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the embodiments.

[0023] Example 1

[0024] A light magnesium alloy automobile wheel hub, the raw materials of which include pure magnesium, pure zinc, magnesium-zirconium master alloy, magnesium-antimony master alloy, magnesium-cerium master alloy, magnesium-manganese-lanthanum alloy and modified boron carbide; the magnesium-zirconium master alloy is a Mg-30wt.% Zr master alloy, the magnesium-antimony master alloy is a Mg-10wt.% Sb master alloy, the magnesium-cerium master alloy is a Mg-20wt.% Ce master alloy, the magnesium-manganese-lanthanum alloy is a Mg 96 Mn3La1 alloy. The magnesium alloy comprises the following elements by weight: Zn 3%, Zr 0.8%, Sb 0.3%, Ce 3%, Mn 0.6%, La 0.2%, modified boron carbide 0.3%, and the remainder Mg. The preparation method of the modified boron carbide is as follows:

[0025] Step 1, polyvinyl alcohol (degree of polymerization 500) and boric acid are mixed to form a mixture, wherein the mass ratio of polyvinyl alcohol to boric acid is polyvinyl alcohol: boric acid = 3:1; the mixture is heated to 200±5°C and kept warm for 50min, and then heated to 250±5°C and kept warm for 80min after the insulation is completed, and then heated to 750±10°C and kept warm for 120min after the insulation is completed, and then air-cooled to room temperature, and heated again to 1450±10°C in an argon atmosphere, kept warm for 2h, and then air-cooled to room temperature to obtain a product powder, and the product powder is wet-milled, and in the wet-milling, the material-ball ratio is material: ball: water = 1:1.8:1; ball milled in a planetary ball mill for 7h at a speed of 100r / min; the slurry is passed through a 1500 mesh sieve, the sieved slurry is dried to obtain boron carbide powder;

[0026] Step 2: preparing a mixed solution of lead dichloride, tin dichloride, and hydrochloric acid, wherein the concentration of lead dichloride is 0.4 g / L, the concentration of tin dichloride is 25 g / L, the mass percentage of hydrogen chloride is 2%, and the solvent is water; the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is kept constant at 60±2° C. in a water bath, and then the boron carbide powder is immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid for 30 minutes, and the solid-liquid mass ratio of the boron carbide powder immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is solid / liquid=1:50; solid-liquid separation is performed, the solid phase is washed with deionized water to remove the residual mixed solution, and the mixture is dried to obtain an activated powder;

[0027] Step 3: Prepare copper sulfate, potassium sodium tartrate, sodium hypophosphite, polyvinyl pyrrolidone (average molecular weight 3.0×10 4), a mixed solution of nickel sulfate, disodium edetate, sodium diphenylamine sulfonate and formaldehyde as a plating solution, wherein the concentration of copper sulfate is 6g / L, the concentration of potassium sodium tartrate is 10g / L, the concentration of sodium hypophosphite is 20g / L, the concentration of polyvinyl pyrrolidone is 20mg / L, the concentration of nickel sulfate is 1g / L, the concentration of disodium edetate is 15g / L, the concentration of sodium diphenylamine sulfonate is 30mg / L, the mass percentage of formaldehyde is 25%, and the solvent is water; the plating solution is kept at a constant temperature of 65±5°C in a water bath, and then the activated powder is added to the plating solution to obtain A mixed solution is obtained, and the activated powder is added to the plating solution at a solid-liquid mass ratio of 1:50; the mixed solution is stirred at a constant temperature of 65±5° C., and during the stirring process, a sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to 13, wherein the concentration of sodium hydroxide in the sodium hydroxide solution is 1 mol / L, and the solvent is water; the mixed solution is then kept warm and stirred for 30 minutes, and the sodium hydroxide solution is added every five minutes during the insulation process to adjust the pH of the mixed solution to 13; after the insulation is completed, the mixed solution is air-cooled to room temperature, solid-liquid separation is performed, the solid phase is washed with deionized water to remove residual plating solution, and the solution is dried to obtain the modified boron carbide.

[0028] The preparation method of the above-mentioned lightweight magnesium alloy automobile wheel hub is as follows:

[0029] (1) Weighing each raw material according to the weight percentage, and polishing the surface of each raw material with sandpaper to remove the oxide scale; placing the pure magnesium in a crucible and heating it to 500° C., introducing a protective gas (a mixture of carbon dioxide and sulfur hexafluoride, wherein the volume ratio of carbon dioxide and sulfur hexafluoride is carbon dioxide:sulfur hexafluoride = 99:1) so that the smelting is carried out in a protective gas environment, and continuing to heat the pure magnesium until it melts to obtain a melt. After the melt is heated to 700° C., the pure zinc is added to the melt, and the temperature is kept to allow the pure zinc to completely melt, and then the temperature is raised to 740° C. ℃, adding the magnesium-antimony master alloy and the magnesium-cerium master alloy into the melt, and after the magnesium-antimony master alloy and the magnesium-cerium master alloy are melted into the melt, heating to 780℃ and maintaining the temperature, adding the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy into the melt, stirring the melt for 30 minutes after the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are melted into the melt, adding a refining agent to the melt for refining, and then cooling to 720℃ for slagging, adding modified boron carbide, stirring the melt for 10 minutes, and immediately casting it into a mold cavity to obtain a magnesium alloy billet;

[0030] (2) heating the magnesium alloy billet to 520±5°C and holding the temperature for 12 hours, then quenching the billet with water to room temperature, and then extruding the billet in an extrusion die. The extrusion deformation process parameters are: extrusion temperature of 420°C, extrusion speed of 25 mm / min, and extrusion ratio of 12; obtaining an extruded billet;

[0031] (3) The extruded billet is placed at 200° C. for aging for 120 hours, then air-cooled to room temperature, polished to remove surface oxide scale, and cut into the automobile wheel hub.

[0032] Example 2

[0033] A light magnesium alloy automobile wheel hub, the raw materials of which include pure magnesium, pure zinc, magnesium-zirconium master alloy, magnesium-antimony master alloy, magnesium-cerium master alloy, magnesium-manganese-lanthanum alloy and modified boron carbide; the magnesium-zirconium master alloy is a Mg-30wt.% Zr master alloy, the magnesium-antimony master alloy is a Mg-10wt.% Sb master alloy, the magnesium-cerium master alloy is a Mg-20wt.% Ce master alloy, the magnesium-manganese-lanthanum alloy is a Mg 96 Mn3La1 alloy. The magnesium alloy comprises the following elements by weight: Zn 4%, Zr 0.9%, Sb 0.5%, Ce 4%, Mn 0.6%, La 0.2%, modified boron carbide 0.3%, and the remainder Mg. The preparation method of the modified boron carbide is as follows:

[0034] Step 1, polyvinyl alcohol (degree of polymerization 500) and boric acid are mixed to form a mixture, wherein the mass ratio of polyvinyl alcohol to boric acid is polyvinyl alcohol: boric acid = 3:1; the mixture is heated to 200±5°C and kept warm for 50min, and then heated to 250±5°C and kept warm for 80min after the insulation is completed, and then heated to 750±10°C and kept warm for 120min after the insulation is completed, and then air-cooled to room temperature, and heated again to 1450±10°C in an argon atmosphere, kept warm for 2h, and then air-cooled to room temperature to obtain a product powder, and the product powder is wet-milled, and in the wet-milling, the material-ball ratio is material: ball: water = 1:1.8:1; ball milled in a planetary ball mill for 7h at a speed of 100r / min; the slurry is passed through a 1500 mesh sieve, the sieved slurry is dried to obtain boron carbide powder;

[0035] Step 2: preparing a mixed solution of lead dichloride, tin dichloride, and hydrochloric acid, wherein the concentration of lead dichloride is 0.4 g / L, the concentration of tin dichloride is 25 g / L, the mass percentage of hydrogen chloride is 2%, and the solvent is water; the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is kept constant at 60±2° C. in a water bath, and then the boron carbide powder is immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid for 30 minutes, and the solid-liquid mass ratio of the boron carbide powder immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is solid / liquid=1:50; solid-liquid separation is performed, the solid phase is washed with deionized water to remove the residual mixed solution, and the mixture is dried to obtain an activated powder;

[0036] Step 3: Prepare copper sulfate, potassium sodium tartrate, sodium hypophosphite, polyvinyl pyrrolidone (average molecular weight 3.0×10 4), a mixed solution of nickel sulfate, disodium edetate, sodium diphenylamine sulfonate and formaldehyde as a plating solution, wherein the concentration of copper sulfate is 7g / L, the concentration of potassium sodium tartrate is 12g / L, the concentration of sodium hypophosphite is 21g / L, the concentration of polyvinyl pyrrolidone is 22mg / L, the concentration of nickel sulfate is 1g / L, the concentration of disodium edetate is 16g / L, the concentration of sodium diphenylamine sulfonate is 34mg / L, the mass percentage of formaldehyde is 25%, and the solvent is water; the plating solution is kept at a constant temperature of 65±5°C in a water bath, and then the activated powder is added to the plating solution to obtain A mixed solution is obtained, and the activated powder is added to the plating solution at a solid-liquid mass ratio of 1:50; the mixed solution is stirred at a constant temperature of 65±5° C., and during the stirring process, a sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to 13, wherein the concentration of sodium hydroxide in the sodium hydroxide solution is 1 mol / L, and the solvent is water; the mixed solution is then kept warm and stirred for 30 minutes, and the sodium hydroxide solution is added every five minutes during the insulation process to adjust the pH of the mixed solution to 13; after the insulation is completed, the mixed solution is air-cooled to room temperature, solid-liquid separation is performed, the solid phase is washed with deionized water to remove residual plating solution, and the solution is dried to obtain the modified boron carbide.

[0037] The preparation method of the above-mentioned lightweight magnesium alloy automobile wheel hub is as follows:

[0038] (1) Weighing each raw material according to the weight percentage, and polishing the surface of each raw material with sandpaper to remove the oxide scale; placing the pure magnesium in a crucible and heating it to 500° C., introducing a protective gas (a mixture of carbon dioxide and sulfur hexafluoride, wherein the volume ratio of carbon dioxide and sulfur hexafluoride is carbon dioxide:sulfur hexafluoride = 99:1) so that the smelting is carried out in a protective gas environment, and continuing to heat the pure magnesium until it melts to obtain a melt. After the melt is heated to 700° C., the pure zinc is added to the melt, and the temperature is kept to allow the pure zinc to completely melt, and then the temperature is raised to 740° C. ℃, adding the magnesium-antimony master alloy and the magnesium-cerium master alloy into the melt, and after the magnesium-antimony master alloy and the magnesium-cerium master alloy are melted into the melt, heating to 780℃ and maintaining the temperature, adding the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy into the melt, stirring the melt for 30 minutes after the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are melted into the melt, adding a refining agent to the melt for refining, and then cooling to 720℃ for slagging, adding modified boron carbide, stirring the melt for 10 minutes, and immediately casting it into a mold cavity to obtain a magnesium alloy billet;

[0039] (2) heating the magnesium alloy billet to 520±5°C and holding the temperature for 12 hours, then quenching the billet with water to room temperature, and then extruding the billet in an extrusion die. The extrusion deformation process parameters are: extrusion temperature of 420°C, extrusion speed of 25 mm / min, and extrusion ratio of 12; obtaining an extruded billet;

[0040] (3) The extruded billet is placed at 200° C. for aging for 120 hours, then air-cooled to room temperature, polished to remove surface oxide scale, and cut into the automobile wheel hub.

[0041] Example 3

[0042] A light magnesium alloy automobile wheel hub, the raw materials of which include pure magnesium, pure zinc, magnesium-zirconium master alloy, magnesium-antimony master alloy, magnesium-cerium master alloy, magnesium-manganese-lanthanum alloy and modified boron carbide; the magnesium-zirconium master alloy is a Mg-30wt.% Zr master alloy, the magnesium-antimony master alloy is a Mg-10wt.% Sb master alloy, the magnesium-cerium master alloy is a Mg-20wt.% Ce master alloy, the magnesium-manganese-lanthanum alloy is a Mg 96 Mn3La1 alloy. The elements of the magnesium alloy are as follows by weight: Zn 4%, Zr 0.9%, Sb 0.5%, Ce 5%, Mn 0.9%, La 0.3%, modified boron carbide 0.4%, and the remainder is Mg. The preparation method of the modified boron carbide is as follows:

[0043] Step 1, polyvinyl alcohol (degree of polymerization 500) and boric acid are mixed to form a mixture, wherein the mass ratio of polyvinyl alcohol to boric acid is polyvinyl alcohol: boric acid = 4:1; the mixture is heated to 200±5°C and kept warm for 50min, and then heated to 250±5°C and kept warm for 80min after the insulation is completed, and then heated to 750±10°C and kept warm for 120min after the insulation is completed, and then air-cooled to room temperature, and heated again to 1450±10°C in an argon atmosphere, kept warm for 2h, and then air-cooled to room temperature to obtain a product powder, and the product powder is wet-milled, and in the wet-milling, the material-ball ratio is material: ball: water = 1:1.8:1; ball milled in a planetary ball mill for 7h at a speed of 100r / min; the slurry is passed through a 1500 mesh sieve, the sieved slurry is dried to obtain boron carbide powder;

[0044] Step 2: preparing a mixed solution of lead dichloride, tin dichloride, and hydrochloric acid, wherein the concentration of lead dichloride is 0.4 g / L, the concentration of tin dichloride is 25 g / L, the mass percentage of hydrogen chloride is 2%, and the solvent is water; the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is kept constant at 60±2° C. in a water bath, and then the boron carbide powder is immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid for 30 minutes, and the solid-liquid mass ratio of the boron carbide powder immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is solid / liquid=1:50; solid-liquid separation is performed, the solid phase is washed with deionized water to remove the residual mixed solution, and the mixture is dried to obtain an activated powder;

[0045] Step 3: Prepare copper sulfate, potassium sodium tartrate, sodium hypophosphite, polyvinyl pyrrolidone (average molecular weight 3.0×10 4), a mixed solution of nickel sulfate, disodium edetate, sodium diphenylamine sulfonate and formaldehyde as a plating solution, wherein the concentration of copper sulfate is 7g / L, the concentration of potassium sodium tartrate is 12g / L, the concentration of sodium hypophosphite is 21g / L, the concentration of polyvinyl pyrrolidone is 23mg / L, the concentration of nickel sulfate is 2g / L, the concentration of disodium edetate is 17g / L, the concentration of sodium diphenylamine sulfonate is 38mg / L, the mass percentage of formaldehyde is 25%, and the solvent is water; the plating solution is kept at a constant temperature of 65±5°C in a water bath, and then the activated powder is added to the plating solution to obtain A mixed solution is obtained, and the activated powder is added to the plating solution at a solid-liquid mass ratio of 1:50; the mixed solution is stirred at a constant temperature of 65±5° C., and during the stirring process, a sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to 13, wherein the concentration of sodium hydroxide in the sodium hydroxide solution is 1 mol / L, and the solvent is water; the mixed solution is then kept warm and stirred for 30 minutes, and the sodium hydroxide solution is added every five minutes during the insulation process to adjust the pH of the mixed solution to 13; after the insulation is completed, the mixed solution is air-cooled to room temperature, solid-liquid separation is performed, the solid phase is washed with deionized water to remove residual plating solution, and the solution is dried to obtain the modified boron carbide.

[0046] The preparation method of the above-mentioned lightweight magnesium alloy automobile wheel hub is as follows:

[0047] (1) Weighing each raw material according to the weight percentage, and polishing the surface of each raw material with sandpaper to remove the oxide scale; placing the pure magnesium in a crucible and heating it to 500° C., introducing a protective gas (a mixture of carbon dioxide and sulfur hexafluoride, wherein the volume ratio of carbon dioxide and sulfur hexafluoride is carbon dioxide:sulfur hexafluoride = 99:1) so that the smelting is carried out in a protective gas environment, and continuing to heat the pure magnesium until it melts to obtain a melt. After the melt is heated to 700° C., the pure zinc is added to the melt, and the temperature is kept to allow the pure zinc to completely melt, and then the temperature is raised to 740° C. ℃, adding the magnesium-antimony master alloy and the magnesium-cerium master alloy into the melt, and after the magnesium-antimony master alloy and the magnesium-cerium master alloy are melted into the melt, heating to 780℃ and maintaining the temperature, adding the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy into the melt, stirring the melt for 30 minutes after the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are melted into the melt, adding a refining agent to the melt for refining, and then cooling to 720℃ for slagging, adding modified boron carbide, stirring the melt for 10 minutes, and immediately casting it into a mold cavity to obtain a magnesium alloy billet;

[0048] (2) heating the magnesium alloy billet to 520±5°C and holding the temperature for 12 hours, then quenching the billet with water to room temperature, and then extruding the billet in an extrusion die. The extrusion deformation process parameters are: extrusion temperature of 420°C, extrusion speed of 25 mm / min, and extrusion ratio of 12; obtaining an extruded billet;

[0049] (3) The extruded billet is placed at 200° C. for aging for 120 hours, then air-cooled to room temperature, polished to remove surface oxide scale, and cut into the automobile wheel hub.

[0050] Example 4

[0051] A light magnesium alloy automobile wheel hub, the raw materials of which include pure magnesium, pure zinc, magnesium-zirconium master alloy, magnesium-antimony master alloy, magnesium-cerium master alloy, magnesium-manganese-lanthanum alloy and modified boron carbide; the magnesium-zirconium master alloy is a Mg-30wt.% Zr master alloy, the magnesium-antimony master alloy is a Mg-10wt.% Sb master alloy, the magnesium-cerium master alloy is a Mg-20wt.% Ce master alloy, the magnesium-manganese-lanthanum alloy is a Mg 96 Mn3La1 alloy. The magnesium alloy comprises the following elements by weight: Zn 5%, Zr 1.0%, Sb 0.7%, Ce 6%, Mn 0.9%, La 0.3%, modified boron carbide 0.4%, and the remainder Mg. The preparation method of the modified boron carbide is as follows:

[0052] Step 1, polyvinyl alcohol (degree of polymerization 500) and boric acid are mixed to form a mixture, wherein the mass ratio of polyvinyl alcohol to boric acid is polyvinyl alcohol: boric acid = 4:1; the mixture is heated to 200±5°C and kept warm for 50min, and then heated to 250±5°C and kept warm for 80min after the insulation is completed, and then heated to 750±10°C and kept warm for 120min after the insulation is completed, and then air-cooled to room temperature, and heated again to 1450±10°C in an argon atmosphere, kept warm for 2h, and then air-cooled to room temperature to obtain a product powder, and the product powder is wet-milled, and in the wet-milling, the material-ball ratio is material: ball: water = 1:1.8:1; ball milled in a planetary ball mill for 7h at a speed of 100r / min; the slurry is passed through a 1500 mesh sieve, the sieved slurry is dried to obtain boron carbide powder;

[0053] Step 2: preparing a mixed solution of lead dichloride, tin dichloride, and hydrochloric acid, wherein the concentration of lead dichloride is 0.4 g / L, the concentration of tin dichloride is 25 g / L, the mass percentage of hydrogen chloride is 2%, and the solvent is water; the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is kept constant at 60±2° C. in a water bath, and then the boron carbide powder is immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid for 30 minutes, and the solid-liquid mass ratio of the boron carbide powder immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is solid / liquid=1:50; solid-liquid separation is performed, the solid phase is washed with deionized water to remove the residual mixed solution, and the mixture is dried to obtain an activated powder;

[0054] Step 3: Prepare copper sulfate, potassium sodium tartrate, sodium hypophosphite, polyvinyl pyrrolidone (average molecular weight 3.0×10 4), a mixed solution of nickel sulfate, disodium edetate, sodium diphenylamine sulfonate and formaldehyde as a plating solution, wherein the concentration of copper sulfate is 8g / L, the concentration of potassium sodium tartrate is 14g / L, the concentration of sodium hypophosphite is 22g / L, the concentration of polyvinyl pyrrolidone is 25mg / L, the concentration of nickel sulfate is 2g / L, the concentration of disodium edetate is 18g / L, the concentration of sodium diphenylamine sulfonate is 40mg / L, the mass percentage of formaldehyde is 25%, and the solvent is water; the plating solution is kept at a constant temperature of 65±5°C in a water bath, and then the activated powder is added to the plating solution to obtain A mixed solution is obtained, and the activated powder is added to the plating solution at a solid-liquid mass ratio of 1:50; the mixed solution is stirred at a constant temperature of 65±5° C., and during the stirring process, a sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to 13, wherein the concentration of sodium hydroxide in the sodium hydroxide solution is 1 mol / L, and the solvent is water; the mixed solution is then kept warm and stirred for 30 minutes, and the sodium hydroxide solution is added every five minutes during the insulation process to adjust the pH of the mixed solution to 13; after the insulation is completed, the mixed solution is air-cooled to room temperature, solid-liquid separation is performed, the solid phase is washed with deionized water to remove residual plating solution, and the solution is dried to obtain the modified boron carbide.

[0055] The preparation method of the above-mentioned lightweight magnesium alloy automobile wheel hub is as follows:

[0056] (1) Weighing each raw material according to the weight percentage, and polishing the surface of each raw material with sandpaper to remove the oxide scale; placing the pure magnesium in a crucible and heating it to 500° C., introducing a protective gas (a mixture of carbon dioxide and sulfur hexafluoride, wherein the volume ratio of carbon dioxide and sulfur hexafluoride is carbon dioxide:sulfur hexafluoride = 99:1) so that the smelting is carried out in a protective gas environment, and continuing to heat the pure magnesium until it melts to obtain a melt. After the melt is heated to 700° C., the pure zinc is added to the melt, and the temperature is kept to allow the pure zinc to completely melt, and then the temperature is raised to 740° C. ℃, adding the magnesium-antimony master alloy and the magnesium-cerium master alloy into the melt, and after the magnesium-antimony master alloy and the magnesium-cerium master alloy are melted into the melt, heating to 780℃ and maintaining the temperature, adding the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy into the melt, stirring the melt for 30 minutes after the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are melted into the melt, adding a refining agent to the melt for refining, and then cooling to 720℃ for slagging, adding modified boron carbide, stirring the melt for 10 minutes, and immediately casting it into a mold cavity to obtain a magnesium alloy billet;

[0057] (2) heating the magnesium alloy billet to 520±5°C and holding the temperature for 12 hours, then quenching the billet with water to room temperature, and then extruding the billet in an extrusion die. The extrusion deformation process parameters are: extrusion temperature of 420°C, extrusion speed of 25 mm / min, and extrusion ratio of 12; obtaining an extruded billet;

[0058] (3) The extruded billet is placed at 200° C. for aging for 120 hours, then air-cooled to room temperature, polished to remove surface oxide scale, and cut into the automobile wheel hub.

[0059] Comparative Example 1

[0060] A comparative light magnesium alloy automobile wheel hub, the raw materials of which include pure magnesium, pure zinc, magnesium-zirconium master alloy, magnesium-antimony master alloy, magnesium-cerium master alloy and magnesium-manganese-lanthanum alloy; the magnesium-zirconium master alloy is a Mg-30wt.% Zr master alloy, the magnesium-antimony master alloy is a Mg-10wt.% Sb master alloy, the magnesium-cerium master alloy is a Mg-20wt.% Ce master alloy, the magnesium-manganese-lanthanum alloy is a Mg 96 Mn3La1 alloy. The magnesium alloy comprises the following elements by weight: Zn 4%, Zr 0.9%, Sb 0.5%, Ce 4%, Mn 0.6%, La 0.2%, and the remainder is Mg.

[0061] The preparation method of the above-mentioned lightweight magnesium alloy automobile wheel hub is as follows:

[0062] (1) Weighing each raw material according to the weight percentage, and polishing the surface of each raw material with sandpaper to remove the oxide scale; placing the pure magnesium in a crucible and heating it, and then heating it to 500° C. and then introducing a protective gas (a mixture of carbon dioxide and sulfur hexafluoride, wherein the volume ratio of carbon dioxide and sulfur hexafluoride is carbon dioxide: sulfur hexafluoride = 99:1) so that the smelting is carried out in a protective gas environment, and continuing to heat the pure magnesium until it melts to obtain a melt, and after the melt is heated to 700° C., adding the pure zinc to the melt, and keeping the temperature to allow the pure zinc to completely melt. The magnesium-antimony master alloy and the magnesium-cerium master alloy are fully melted, and then the temperature is raised to 740° C., and the magnesium-antimony master alloy and the magnesium-cerium master alloy are added to the melt. After the magnesium-antimony master alloy and the magnesium-cerium master alloy are melted into the melt, the temperature is raised to 780° C. and kept warm. The magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are added to the melt. After the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are melted into the melt, the melt is stirred for 30 minutes to mix. A refining agent is added to the melt for refining, and then the temperature is lowered to 720° C. to skim off the slag, and cast into a mold cavity to obtain a magnesium alloy billet.

[0063] (2) heating the magnesium alloy billet to 520±5°C and holding the temperature for 12 hours, then quenching the billet with water to room temperature, and then extruding the billet in an extrusion die. The extrusion deformation process parameters are: extrusion temperature of 420°C, extrusion speed of 25 mm / min, and extrusion ratio of 12; obtaining an extruded billet;

[0064] (3) The extruded billet is placed at 200° C. for aging for 120 hours, then air-cooled to room temperature, polished to remove surface oxide scale, and cut into the automobile wheel hub.

[0065] Comparative Example 2

[0066] A comparative light magnesium alloy automobile wheel hub, the raw materials of which include pure magnesium, pure zinc, magnesium-zirconium master alloy, magnesium-antimony master alloy, magnesium-cerium master alloy, magnesium-manganese-lanthanum alloy and boron carbide; the magnesium-zirconium master alloy is a Mg-30wt.% Zr master alloy, the magnesium-antimony master alloy is a Mg-10wt.% Sb master alloy, the magnesium-cerium master alloy is a Mg-20wt.% Ce master alloy, the magnesium-manganese-lanthanum alloy is a Mg 96 The magnesium alloy comprises the following elements by weight: Zn 4%, Zr 0.9%, Sb 0.5%, Ce 4%, Mn 0.6%, La 0.2%, boron carbide 0.3%, and the remainder Mg. The preparation method of the boron carbide is as follows: polyvinyl alcohol (degree of polymerization 500) and boric acid are mixed to form a mixture, wherein the mass ratio of the polyvinyl alcohol to boric acid is polyvinyl alcohol: boric acid = 3:1; the mixture is heated to 200±5°C and kept warm for 50 minutes, and then heated to 250±5°C and kept warm for 80 minutes after the end of the insulation, and then heated to 750±10°C and kept warm for 120 minutes after the end of the insulation, and then air-cooled to room temperature, and heated again to 1450±10°C in an argon atmosphere, kept warm for 2 hours, and then air-cooled to room temperature to obtain a product powder, and the product powder is wet-milled, wherein the material-ball ratio is material: ball: water = 1:1.8:1; the ball mill is used in a planetary ball mill for 7 hours at a speed of 100 r / min; the slurry is passed through a 1500 mesh sieve, the sieved slurry is dried to obtain the boron carbide powder described in this comparative example.

[0067] The preparation method of the above-mentioned lightweight magnesium alloy automobile wheel hub is as follows:

[0068] (1) Weighing each raw material according to the weight percentage, and polishing the surface of each raw material with sandpaper to remove the oxide scale; placing the pure magnesium in a crucible and heating it to 500° C., introducing a protective gas (a mixture of carbon dioxide and sulfur hexafluoride, wherein the volume ratio of carbon dioxide and sulfur hexafluoride is carbon dioxide:sulfur hexafluoride = 99:1) so that the smelting is carried out in a protective gas environment, and continuing to heat the pure magnesium until it melts to obtain a melt. After the melt is heated to 700° C., the pure zinc is added to the melt, and the temperature is kept to allow the pure zinc to completely melt, and then the temperature is raised to 740° C. ℃, adding the magnesium-antimony master alloy and the magnesium-cerium master alloy into the melt, and after the magnesium-antimony master alloy and the magnesium-cerium master alloy are melted into the melt, heating to 780℃ and maintaining the temperature, adding the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy into the melt, stirring the melt for 30 minutes after the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are melted into the melt, adding a refining agent to the melt for refining, and then cooling to 720℃ for slagging, adding the boron carbide, stirring the melt for 10 minutes, and immediately casting it into a mold cavity to obtain a magnesium alloy billet;

[0069] (2) heating the magnesium alloy billet to 520±5°C and holding the temperature for 12 hours, then quenching the billet with water to room temperature, and then extruding the billet in an extrusion die. The extrusion deformation process parameters are: extrusion temperature of 420°C, extrusion speed of 25 mm / min, and extrusion ratio of 12; obtaining an extruded billet;

[0070] (3) The extruded billet is placed at 200° C. for aging for 120 hours, then air-cooled to room temperature, polished to remove surface oxide scale, and cut into the automobile wheel hub.

[0071] Comparative Example 3

[0072] A comparative lightweight magnesium alloy automobile wheel hub comprises raw materials including pure magnesium, pure zinc, a magnesium-zirconium master alloy, a magnesium-antimony master alloy, a magnesium-cerium master alloy, a magnesium-manganese master alloy, a magnesium-lanthanum master alloy, and modified boron carbide. The magnesium-zirconium master alloy is a Mg-30wt.% Zr master alloy, the magnesium-antimony master alloy is a Mg-10wt.% Sb master alloy, the magnesium-cerium master alloy is a Mg-20wt.% Ce master alloy, the magnesium-manganese master alloy is a Mg-10wt.% Mn master alloy, and the magnesium-lanthanum master alloy is a Mg-10wt.% La master alloy. The magnesium alloy comprises the following elements by weight: Zn 4%, Zr 0.9%, Sb 0.5%, Ce 4%, Mn 0.6%, La 0.2%, modified boron carbide 0.3%, and the remainder is Mg. The modified boron carbide is prepared by:

[0073] Step 1, polyvinyl alcohol (degree of polymerization 500) and boric acid are mixed to form a mixture, wherein the mass ratio of polyvinyl alcohol to boric acid is polyvinyl alcohol: boric acid = 3:1; the mixture is heated to 200±5°C and kept warm for 50min, and then heated to 250±5°C and kept warm for 80min after the insulation is completed, and then heated to 750±10°C and kept warm for 120min after the insulation is completed, and then air-cooled to room temperature, and heated again to 1450±10°C in an argon atmosphere, kept warm for 2h, and then air-cooled to room temperature to obtain a product powder, and the product powder is wet-milled, and in the wet-milling, the material-ball ratio is material: ball: water = 1:1.8:1; ball milled in a planetary ball mill for 7h at a speed of 100r / min; the slurry is passed through a 1500 mesh sieve, the sieved slurry is dried to obtain boron carbide powder;

[0074] Step 2: preparing a mixed solution of lead dichloride, tin dichloride, and hydrochloric acid, wherein the concentration of lead dichloride is 0.4 g / L, the concentration of tin dichloride is 25 g / L, the mass percentage of hydrogen chloride is 2%, and the solvent is water; the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is kept constant at 60±2° C. in a water bath, and then the boron carbide powder is immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid for 30 minutes, and the solid-liquid mass ratio of the boron carbide powder immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is solid / liquid=1:50; solid-liquid separation is performed, the solid phase is washed with deionized water to remove the residual mixed solution, and the mixture is dried to obtain an activated powder;

[0075] Step 3: Prepare copper sulfate, potassium sodium tartrate, sodium hypophosphite, polyvinyl pyrrolidone (average molecular weight 3.0×10 4 ), a mixed solution of nickel sulfate, disodium edetate, sodium diphenylamine sulfonate and formaldehyde as a plating solution, wherein the concentration of copper sulfate is 7g / L, the concentration of potassium sodium tartrate is 12g / L, the concentration of sodium hypophosphite is 21g / L, the concentration of polyvinyl pyrrolidone is 22mg / L, the concentration of nickel sulfate is 1g / L, the concentration of disodium edetate is 16g / L, the concentration of sodium diphenylamine sulfonate is 34mg / L, the mass percentage of formaldehyde is 25%, and the solvent is water; the plating solution is kept at a constant temperature of 65±5°C in a water bath, and then the activated powder is added to the plating solution to obtain A mixed solution is obtained, and the activated powder is added to the plating solution at a solid-liquid mass ratio of 1:50; the mixed solution is stirred at a constant temperature of 65±5° C., and during the stirring process, a sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to 13, wherein the concentration of sodium hydroxide in the sodium hydroxide solution is 1 mol / L, and the solvent is water; the mixed solution is then kept warm and stirred for 30 minutes, and the sodium hydroxide solution is added every five minutes during the insulation process to adjust the pH of the mixed solution to 13; after the insulation is completed, the mixed solution is air-cooled to room temperature, solid-liquid separation is performed, the solid phase is washed with deionized water to remove residual plating solution, and the solution is dried to obtain the modified boron carbide.

[0076] The preparation method of the above-mentioned lightweight magnesium alloy automobile wheel hub is as follows:

[0077] (1) Weighing each raw material according to the weight percentage, and polishing the surface of each raw material with sandpaper to remove the oxide scale; placing the pure magnesium in a crucible and heating it, and after heating to 500° C., introducing a protective gas (a mixture of carbon dioxide and sulfur hexafluoride, the volume ratio of carbon dioxide and sulfur hexafluoride is carbon dioxide: sulfur hexafluoride = 99:1) so that the smelting is carried out in a protective gas environment, and continuing to heat the pure magnesium until it melts to obtain a melt, and after the melt is heated to 700° C., adding the pure zinc to the melt, and keeping the temperature to make the pure zinc completely melted, and then heating to 740° C., adding the pure zinc to the melt. The magnesium-antimony master alloy and the magnesium-cerium master alloy are melted into a melt, and then the temperature is raised to 780° C. and maintained, and the magnesium-zirconium master alloy, the magnesium-manganese master alloy, and the magnesium-lanthanum master alloy are added to the melt, and the magnesium-zirconium master alloy, the magnesium-manganese master alloy, and the magnesium-lanthanum master alloy are melted into the melt and stirred for 30 minutes to mix, and a refining agent is added to the melt for refining, and then the temperature is lowered to 720° C. and slag is skimmed, and then modified boron carbide is added, and the melt is stirred for 10 minutes and then immediately cast into a mold cavity to obtain a magnesium alloy billet;

[0078] (2) heating the magnesium alloy billet to 520±5°C and holding the temperature for 12 hours, then quenching the billet with water to room temperature, and then extruding the billet in an extrusion die. The extrusion deformation process parameters are: extrusion temperature of 420°C, extrusion speed of 25 mm / min, and extrusion ratio of 12; obtaining an extruded billet;

[0079] (3) The extruded billet is placed at 200° C. for aging for 120 hours, then air-cooled to room temperature, polished to remove surface oxide scale, and cut into the automobile wheel hub.

[0080] Example 5

[0081] According to the requirements of GB / T16865-2013, the magnesium alloy automobile wheels prepared by the methods described in the above embodiments and comparative examples were cut into tensile specimens (rectangular specimens). The tensile strength of each group of tensile specimens was tested using a universal material testing machine. Four tensile specimens were prepared for each group and tested independently four times. The average value of the test data was taken as the tensile strength value of the material in this group. The results are shown in Figure 2. Figure 1 shown.

[0082] Depend on Figure 1It can be seen that the magnesium alloy prepared by the method of the present invention has a high tensile strength and exhibits good mechanical properties. This may be mainly due to the fine grain strengthening and second phase strengthening effect after adding modified boron carbide and magnesium-manganese-lanthanum alloy. Comparative Example 2 and the comparative examples show that the direct addition of boron carbide to the alloy without surface treatment does not significantly improve the mechanical properties of the alloy. This may be because although the introduction of boron carbide can achieve a certain fine grain effect, the relatively poor wettability of unsurfaced boron carbide and the magnesium alloy matrix causes the two-phase interface of boron carbide and magnesium alloy to be weakly bonded. When the material is subjected to external force, it is easy to form holes and microcracks in the two-phase interface area, which is very conducive to the expansion of cracks, resulting in deterioration of mechanical properties.

[0083] The technical solutions provided by the present invention are described in detail above. For those skilled in the art, according to the ideas of the embodiments of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A lightweight magnesium alloy automobile wheel hub, characterized in that: The raw materials include pure magnesium, pure zinc, magnesium-zirconium master alloy, magnesium-antimony master alloy, magnesium-cerium master alloy, magnesium-manganese-lanthanum alloy and modified boron carbide; the magnesium-zirconium master alloy is Mg-30wt.%Zr master alloy, the magnesium-antimony master alloy is Mg-10wt.%Sb master alloy, the magnesium-cerium master alloy is Mg-20wt.%Ce master alloy, the magnesium-manganese-lanthanum alloy is Mg 96 Mn3La1 alloy; the magnesium alloy comprises the following elements by weight percentage: Zn 3% to 5%, Zr 0.8% to 1.0%, Sb 0.3% to 0.7%, Ce 3% to 6%, Mn 0.6% to 0.9%, La 0.2% to 0.3%, modified boron carbide 0.3% to 0.4%, and the remainder is Mg; the preparation method of the modified boron carbide is: Step 1, polyvinyl alcohol and boric acid are mixed to form a mixture, the mixture is heated to 200±5°C and kept warm for 50-60 minutes, and then heated to 250±5°C and kept warm for 80-100 minutes after the end of the heat preservation, and then heated to 750±10°C and kept warm for 120-150 minutes after the end of the heat preservation, and then air-cooled to room temperature, and heated again to 1450±10°C in an argon atmosphere, kept warm for 2-3 hours, and then air-cooled to room temperature to obtain a product powder, the product powder is wet-ball milled, the slurry is passed through a 1500 mesh sieve, the sieved slurry is dried to obtain boron carbide powder; Step 2: preparing a mixed solution of lead dichloride, tin dichloride, and hydrochloric acid, and keeping the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid constant temperature at 60±2° C. in a water bath, then soaking the boron carbide powder in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid for 30 to 40 minutes, separating the solid and the liquid, washing the solid phase with deionized water to remove the residual mixed solution, and drying to obtain an activated powder; Step 3, prepare a mixed solution of copper sulfate, potassium sodium tartrate, sodium hypophosphite, polyvinylpyrrolidone, nickel sulfate, disodium ethylenediaminetetraacetic acid, sodium diphenylamine sulfonate and formaldehyde as a plating solution, keep the plating solution in a water bath at a constant temperature of 65±5°C, then add the activated powder to the plating solution to obtain a mixed solution, stir the mixed solution at a constant temperature of 65±5°C, add sodium hydroxide solution to the mixed solution during the stirring process to adjust the pH of the mixed solution to 13, then keep the mixture warm and stir for 30 to 40 minutes, and add the sodium hydroxide solution every five minutes during the insulation process to adjust the pH of the mixed solution to 13; after the insulation is completed, air cool to room temperature, separate the solid and liquid, wash the solid phase with deionized water to remove the residual plating solution, and dry to obtain the modified boron carbide.

2. The lightweight magnesium alloy automobile wheel hub according to claim 1, characterized in that: The mass ratio of the polyvinyl alcohol and boric acid is polyvinyl alcohol:boric acid=3-4:1; in the wet ball milling, the material-ball ratio is material:ball:water=1:1.8:1; the ball milling is carried out in a planetary ball mill for 7-8 hours at a rotation speed of 100 r / min.

3. The lightweight magnesium alloy automobile wheel hub according to claim 1, characterized in that: In the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid, the concentration of lead dichloride is 0.4-0.5 g / L, the concentration of tin dichloride is 23-28 g / L, the mass percentage of hydrogen chloride is 2%-3%, and the solvent is water; the solid-liquid mass ratio of the boron carbide powder immersed in the mixed solution of lead dichloride, tin dichloride, and hydrochloric acid is solid / liquid=1:

50.

4. The lightweight magnesium alloy automobile wheel hub according to claim 1, characterized in that: In the plating solution, the concentration of copper sulfate is 6-8 g / L, the concentration of potassium sodium tartrate is 10-14 g / L, the concentration of sodium hypophosphite is 20-22 g / L, the concentration of polyvinyl pyrrolidone is 20-25 mg / L, the concentration of nickel sulfate is 1-2 g / L, the concentration of disodium ethylenediaminetetraacetate is 15-18 g / L, the concentration of sodium diphenylamine sulfonate is 30-40 mg / L, the mass percentage of formaldehyde is 25%, and the solvent is water; the activated powder is added to the plating solution at a solid-liquid mass ratio of solid / liquid=1:50; the concentration of sodium hydroxide in the sodium hydroxide solution is 1 mol / L, and the solvent is water.

5. The method for preparing a lightweight magnesium alloy automobile wheel hub according to claim 1, wherein: The steps are: (1) Weigh each raw material according to the weight percentage, and use sandpaper to polish the surface of each raw material to remove the oxide scale; put the pure magnesium into a crucible and heat it. After heating to 500°C, introduce protective gas so that the smelting is carried out in a protective gas environment, continue to heat the pure magnesium until it melts to obtain a melt, after the melt is heated to 690-700°C, add the pure zinc to the melt, keep the temperature so that the pure zinc is completely melted, and then heat it to 730-740°C, add the magnesium-antimony master alloy and the magnesium-cerium master alloy to the melt, and wait for After the magnesium-antimony master alloy and the magnesium-cerium master alloy are melted into the melt, the temperature is raised to 780-785° C. and maintained, the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are added into the melt, the magnesium-zirconium master alloy and the magnesium-manganese-lanthanum alloy are melted into the melt, and the melt is stirred for 30-40 minutes to mix, a refining agent is added to the melt for refining, and the temperature is then lowered to 720-725° C. to skim off the slag, and modified boron carbide is added. The melt is stirred for 10 minutes and then immediately cast into a mold cavity to obtain a magnesium alloy billet; (2) heating the magnesium alloy billet to 520±5° C. and holding the temperature for 12 to 13 hours, then quenching the billet with water to room temperature, and then extruding the billet in an extrusion die to obtain an extruded billet; (3) aging the extruded billet at 200-220° C. for 100-120 h, then air-cooling it to room temperature, grinding it to remove surface oxide scale, and cutting it into the automobile wheel hub.

6. The method for preparing a lightweight magnesium alloy automobile wheel hub according to claim 5, characterized in that: The protective gas is a mixture of carbon dioxide and sulfur hexafluoride, and the volume ratio of the carbon dioxide to sulfur hexafluoride is carbon dioxide:sulfur hexafluoride=99:

1.

7. The method for preparing a lightweight magnesium alloy automobile wheel hub according to claim 5, characterized in that: The extrusion deformation process parameters are: extrusion temperature is 420-430° C., extrusion speed is set at 25-30 mm / min, and extrusion ratio is 12.

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