Magnesium alloy composite bar and preparation method thereof

Abstract

The invention provides a magnesium alloy composite bar and a preparation method thereof. The preparation method comprises the following steps: S1, turning a plurality of holes from the end face of a pure Mg cast ingot, wherein a certain included angle is formed between the holes and the axial direction of the cast ingot; s2, an Mg-RE-Zr alloy bar is arranged in a hole of the pure Mg cast ingot in an interference fit mode, and a magnesium alloy composite bar blank is formed; and S3, preheating and extruding the magnesium alloy composite bar blank to prepare the magnesium alloy composite bar. According to the method, the pure Mg cast ingot and the Mg-RE-Zr alloy which are the same as base materials are compounded in an interference fit mode, the compatibility of a compound interface is better, obvious element diffusion can occur in the extrusion process, the grain size at the interface is refined, metallurgical bonding is achieved at the interface, the interface bonding force is increased, and the advantage of light weight of the magnesium alloy is fully played; the magnesium alloy contains rare earth elements, the microstructure and texture orientation of the magnesium alloy are changed, the room-temperature plastic deformation capacity is improved, and meanwhile the tension-compression asymmetry and anisotropy of the alloy are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and in particular relates to a magnesium alloy composite rod and a preparation method thereof. Background Art

[0002] Magnesium alloy is the metal structural material with the lowest density and has great application value in the fields of aviation, aerospace, military industry, etc. However, due to the close-packed hexagonal structure of magnesium, there are few slip systems that are easy to start during room temperature deformation, and it usually shows poor plastic deformation ability. At present, there are two main methods to improve the room temperature plasticity of magnesium alloys. One is to change the microstructure and texture through alloying, and the other is to homogenize the structure and refine the grains through processing technology and heat treatment.

[0003] In the alloying research of magnesium alloy, the most effective method is to introduce rare earth elements. However, due to the high price of rare earth elements, the cost of single magnesium-rare earth alloy is high and it is difficult to process and shape.

[0004] At present, the connection processes of metal composite materials are mainly diffusion welding, explosion welding, friction welding, etc. The composite preparation methods of layered composite plates also include mechanical rolling composite, hydraulic expansion composite, hot extrusion composite forming process, etc. Among them, the magnesium alloy composite materials formed by welding have defects such as high cost and unstable performance, which are difficult to carry out large-scale industrial production. Composite materials prepared by plastic deformation can make full use of materials, improve the microstructure and properties of alloys, and easily realize industrial continuous production. The production process and equipment of hot extrusion are simple, and the utilization rate of raw materials and production efficiency are high. It is an ideal method for preparing magnesium alloy composite materials. However, there is still insufficient research on the flow velocity, plastic deformation ability, and interface strength of the two metal materials during hot extrusion. How to design a composite method of the two materials to improve their comprehensive performance is a difficulty in the field of composite materials. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the present invention provides a magnesium alloy composite rod and a preparation method thereof.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A method for preparing a magnesium alloy composite rod comprises the following steps:

[0008] S1. Prepare a pure Mg ingot, and turn a plurality of holes from the end surface of the pure Mg ingot, wherein the axial direction of the hole forms a certain angle with the axial direction of the ingot, the centers of the holes on the upper and lower end surfaces of the Mg ingot are on the same circular trajectory, and the circular trajectories of the upper and lower end surfaces of the Mg ingot have the same diameter;

[0009] S2, preparing a plurality of Mg-RE-Zr alloy bars, and interference fitting the Mg-RE-Zr alloy bars into the holes of the pure Mg ingot in S1 to form a magnesium alloy composite bar blank;

[0010] S3. Preheating and extruding the magnesium alloy composite rod blank obtained in S2 to obtain a magnesium alloy composite rod.

[0011] Furthermore, it also includes polishing and cleaning the inner wall of the hole of the pure Mg ingot and the outer wall of the Mg-RE-Zr alloy rod, the polishing method is sandpaper polishing, or grinder polishing, or steel wire ball polishing, and the cleaning method is alcohol rinsing or ultrasonic cleaning.

[0012] Furthermore, RE in the Mg-RE-Zr alloy material in step S1 is one of Gd, Y, Er, Dy, Sm, and Tm.

[0013] Furthermore, the mass percentage of each element in the Mg-RE-Zr alloy material in step S1 is: RE 2.0%-5.0%, Zr 0.3%-1.0%, and the balance is Mg.

[0014] Furthermore, the hole in step S1 is a through hole or a blind hole, and the through hole or the blind hole is preferably cylindrical.

[0015] Furthermore, the number of holes in step S1 is 4 to 8.

[0016] Furthermore, in step S1, the angle between the axial direction of the hole and the axial direction of the ingot is 30°.

[0017] Furthermore, in step S2, the interference between the hole of the Mg-RE-Zr alloy rod and the pure Mg ingot is 0.5-0.8 mm.

[0018] Furthermore, the magnesium alloy composite rod blank prepared in step S2 has a diameter of 80 mm and a height of 50 to 80 mm.

[0019] Furthermore, the Mg-RE-Zr alloy rod in step S2 is made by extruding the Mg-RE-Zr alloy, and the process parameters of the Mg-RE-Zr alloy extruded rod are an extrusion temperature of 350 to 480°C, an extrusion ratio of 8 to 85, an extrusion speed of 5 to 30 m / min, and a diameter of the extruded rod of 8 to 25 mm.

[0020] Furthermore, the mass percentage of each material in the magnesium alloy composite rod in step S3 is: 8% to 50% of Mg-RE-Zr alloy material, and the rest is pure Mg.

[0021] Furthermore, the process parameters for preheating the magnesium alloy composite bar billet and extruding the bar in step S3 are: preheating temperature 300-480°C, preheating time 1-12h, extrusion temperature 300-480°C, extrusion ratio 8-85, and extrusion speed 5-30m / min.

[0022] A magnesium alloy composite rod prepared according to the above preparation method.

[0023] Compared with the prior art, the present invention has at least the following advantages:

[0024] 1. The present invention provides a magnesium alloy composite rod and a preparation method thereof. First, a plurality of holes with a certain angle to the axial direction of the ingot are turned into a pure Mg ingot, and then a Mg-RE-Zr alloy rod is interference-fitted in the holes. The Mg-RE-Zr alloy rod and the pure Mg ingot are assembled in a complete cylinder. After each hole is successfully assembled, the excess rod on the upper and lower end surfaces of the ingot is cut off. The friction between the rod and the pure Mg ingot is increased by interference fit, the final bonding strength is improved, and the material is prevented from falling off and shifting during subsequent processing. During the extrusion process, obvious element diffusion occurs between the Mg / Mg interface, the grain size at the interface is refined, metallurgical bonding is achieved at the interface, and the interface bonding force of the two alloys is increased, thereby effectively improving the comprehensive performance of the alloy. The Mg / Mg composite interface of the Mg-RE-Zr alloy and pure Mg of the present invention is an inclined surface, which increases the contact area between the Mg / Mg alloys. The interference amount of the interference fit is 0.5-0.8 mm. Adjust the sample angle before static pressing, use a hydraulic press to apply pressure, and slowly press the extruded bar into the mold. During the pressing process, use external force to tap and adjust the embedding direction and position of the extruded bar appropriately. After the extruded bar is completely embedded in the ingot, cut off 5mm above and below the ingot to ensure the uniformity of the subsequent organization.

[0025] 2. The present invention provides a magnesium alloy composite rod and a preparation method thereof, which composites two metals of the same type with different properties, pure Mg and Mg-RE-Zr alloy. Pure Mg and Mg-RE-Zr alloy are the same matrix materials, and the interface compatibility is better during the composite process, which can avoid the occurrence of interface cracks and fracture defects. The process is simple, the operation is easy, and the feasibility is high. At the same time, the Mg / Mg material combines the advantages of the two materials. On the premise of meeting the mechanical properties, the cost of the material is reduced, and the advantage of the lightweight magnesium alloy is fully utilized.

[0026] 3. The present invention provides a magnesium alloy composite rod and a preparation method thereof, wherein the materials used are Mg-RE-Zr alloy and pure Mg. The Mg-RE-Zr alloy material contains rare earth elements, and the addition of rare earth elements changes the microstructure and texture orientation of the magnesium alloy, so that the magnesium alloy coordinates the start of basal slip and non-basal slip during deformation, improves the room temperature plastic deformation capacity, and improves the tensile and compressive asymmetry and anisotropy of the alloy.

[0027] 4. When the magnesium alloy composite rod is prepared by the method of the present invention, the extrusion step can be quickly extruded and formed in one time by conventional extrusion equipment, and the process is simple and easy to control; at the same time, the time-consuming and energy-consuming heat treatment process before and after extrusion is omitted, thereby improving production efficiency and saving production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments or the description of the prior art will be briefly introduced below.

[0029] Figure 1 It is a line diagram of a cylindrical billet before extrusion of the composite rod of the present invention.

[0030] Figure 2 This is a metallographic structure diagram at the interface of the composite extruded rod Mg / Mg-2Gd-0.4Zr according to Example 1 of the present invention.

[0031] Figure 3 This is an EBSD IPF (electron backscatter diffraction grain orientation) image at the interface of the composite extruded rod Mg / Mg-2Gd-0.4Zr of Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0033] Embodiment 1

[0034] A method for preparing a magnesium alloy composite rod comprises the following steps.

[0035] S1. Material preparation and processing: prepare a Mg-2Gd-0.4Zr magnesium alloy ingot with a diameter of 80 mm and a length of 100 mm, extrude it at 420°C into an extruded rod with a diameter of 16 mm for standby use, remove the surface of the rod, and obtain 6 extruded rods with a diameter of 15.5 mm and a length of 100 mm; prepare a pure Mg ingot with a diameter of 80 mm and a length of 80 mm, and evenly cut 6 through holes with a diameter of 15 mm on the end face of the pure Mg ingot at a circular position with a diameter of 40 mm, and the axial direction of the through hole is inclined at an angle of 30° to the axial direction of the pure Mg ingot;

[0036] S2. Surface cleaning: Use sandpaper from coarse to fine to polish the inner surface of the through hole of the pure Mg ingot and the outer surface of the magnesium alloy rod in turn. After polishing, rinse with alcohol and then blow dry with a hair dryer;

[0037] S3, assembly and combination: the cleaned and air-dried pure Mg ingot and magnesium alloy rod are assembled and combined, firstly, the magnesium alloy rod is hammered into the hole of the ingot with a hammer; then, a hydraulic press or a hammer is used to apply pressure and slowly push it forward until the magnesium alloy rod is completely embedded in the ingot; then, the excess part of the magnesium alloy rod that is not embedded in the through hole is cut off, and this process is repeated to complete the assembly of all magnesium alloy rods, and a magnesium alloy composite rod blank is obtained;

[0038] S4. Extrusion molding: The magnesium alloy composite rod blank is placed in a resistance furnace for preheating at a temperature of 420° C. for 1 hour, and then extruded in an extruder. The extrusion die is a rod die, the extrusion ratio is 28, and the extrusion speed is 10 m / min to obtain a magnesium alloy composite rod.

[0039] The mechanical properties of the Mg / Mg composite rod prepared in this embodiment are as follows: room temperature tensile strength is 220 MPa, and elongation after fracture is 23%.

[0040] Figure 2 This is the metallographic structure diagram at the interface of the magnesium alloy composite rod Mg / Mg-2Gd-0.4Zr of Example 1 of the present invention. From the analysis of the figure, it can be seen that the grains of the Mg-Gd-Zr regional structure in the present invention are finer, while the grains of the pure Mg regional structure are coarser, which is conducive to the formation of obvious heterogeneous deformation-induced nucleation stress in the subsequent deformation process, thereby enhancing the mechanical properties of the alloy; the Mg-Gd-Zr / pure Mg interface is tightly bonded without obvious defects.

[0041] Figure 3 This is the EBSD IPF at the interface of the magnesium alloy composite rod Mg / Mg-2Gd-0.4Zr of Example 1 of the present invention. From the analysis of the figure, it can be seen that Mg-Gd-Zr shows obvious rare earth texture characteristics, and pure Mg shows obvious extruded fiber texture characteristics. The Mg-Gd-Zr and pure Mg bonding interfaces are tightly bonded, and the Mg-Gd-Zr alloy region close to the bonding interface has finer grains, and the colors are mostly blue and green, and the texture orientation has changed, indicating that the alloy elements of the alloy diffused during the extrusion process, and a small part of the Gd element in the Mg-Gd-Zr diffused into the pure Mg, further illustrating that the bonding degree of the Mg / Mg interface in the present invention is relatively high.

[0042] Embodiment 2

[0043] A method for preparing a magnesium alloy composite rod comprises the following steps.

[0044] S1. Material preparation and processing: prepare a Mg-2Gd-0.4Zr magnesium alloy ingot with a diameter of 80 mm and a length of 100 mm, extrude it at 420°C into an extruded rod with a diameter of 20 mm for standby use, remove the surface of the rod, and obtain 4 extruded rods with a diameter of 19.5 mm and a length of 100 mm; prepare a pure Mg ingot with a diameter of 80 mm and a length of 80 mm, and evenly cut 4 through holes with a diameter of 15 mm on the end face of the pure Mg ingot at a circular position with a diameter of 40 mm, and the axial direction of the through hole is inclined at an angle of 30° to the axial direction of the pure Mg ingot;

[0045] S2. Surface cleaning: Use sandpaper from coarse to fine to polish the inner surface of the through hole of the pure Mg ingot and the outer surface of the magnesium alloy rod in turn. After polishing, rinse with alcohol and then blow dry with a hair dryer;

[0046] S3, assembly and combination: the cleaned and air-dried pure Mg ingot and magnesium alloy rod are assembled and combined, firstly, the magnesium alloy rod is hammered into the hole of the ingot with a hammer; then, a hydraulic press or a hammer is used to apply pressure and slowly push it forward until the magnesium alloy rod is completely embedded in the ingot; then, the excess part of the magnesium alloy rod that is not embedded in the through hole is cut off, and this process is repeated to complete the assembly of all magnesium alloy rods, and a magnesium alloy composite rod blank is obtained;

[0047] S4. Extrusion molding: The magnesium alloy composite rod blank is placed in a resistance furnace for preheating at a temperature of 420° C. for 1 hour, and then extruded in an extruder. The extrusion die is a rod die, the extrusion ratio is 28, and the extrusion speed is 10 m / min to obtain a magnesium alloy composite rod.

[0048] The mechanical properties of the Mg / Mg-2Gd-0.4Zr composite rod prepared in this embodiment are as follows: room temperature tensile strength is 192 MPa, and elongation after fracture is 18%.

[0049] Embodiment 3

[0050] A method for preparing a magnesium alloy composite rod comprises the following steps.

[0051] S1. Material preparation and processing: prepare a Mg-2Gd-0.4Zr magnesium alloy ingot with a diameter of 80 mm and a length of 100 mm, extrude it at 420°C into an extruded rod with a diameter of 16 mm for standby use, remove the surface of the rod, and obtain 6 extruded rods with a diameter of 15.5 mm and a length of 100 mm; prepare a pure Mg ingot with a diameter of 80 mm and a length of 80 mm, and evenly cut 6 through holes with a diameter of 15 mm on the end face of the pure Mg ingot at a circular position with a diameter of 40 mm, and the axial direction of the through hole is inclined at an angle of 30° to the axial direction of the pure Mg ingot;

[0052] S2. Surface cleaning: Use sandpaper from coarse to fine to polish the inner surface of the through hole of the pure Mg ingot and the outer surface of the magnesium alloy rod in turn. After polishing, rinse with alcohol and then blow dry with a hair dryer;

[0053] S3, assembly and combination: the cleaned and air-dried pure Mg ingot and magnesium alloy rod are assembled and combined, firstly, the magnesium alloy rod is hammered into the hole of the ingot with a hammer; then, a hydraulic press or a hammer is used to apply pressure and slowly push it forward until the magnesium alloy rod is completely embedded in the ingot; then, the excess part of the magnesium alloy rod that is not embedded in the through hole is cut off, and this process is repeated to complete the assembly of all magnesium alloy rods, and a magnesium alloy composite rod blank is obtained;

[0054] S4. Extrusion molding: The magnesium alloy composite rod blank is placed in a resistance furnace for preheating at a temperature of 420° C. for 1 hour, and then extruded in an extruder. The extrusion die is a rod die, the extrusion ratio is 85, and the extrusion speed is 10 m / min to obtain a magnesium alloy composite rod.

[0055] The mechanical properties of the Mg / Mg-2Gd-0.4Zr composite rod prepared in this embodiment are as follows: room temperature tensile strength is 233 MPa, and elongation after fracture is 20%.

[0056] Embodiment 4

[0057] A method for preparing a magnesium alloy composite rod comprises the following steps.

[0058] S1. Material preparation and processing: prepare a Mg-2Y-0.6Zr magnesium alloy ingot with a diameter of 80 mm and a length of 100 mm, extrude it at 400°C into an extruded rod with a diameter of 16 mm for standby use, remove the surface of the rod, and obtain 6 extruded rods with a diameter of 15.5 mm and a length of 100 mm; prepare a pure Mg ingot with a diameter of 80 mm and a length of 80 mm, and evenly cut 6 through holes with a diameter of 15 mm on the end face of the pure Mg ingot at a circular position with a diameter of 40 mm, and the axial direction of the through hole is inclined at an angle of 30° to the axial direction of the pure Mg ingot;

[0059] S2. Surface cleaning: Use sandpaper from coarse to fine to polish the inner surface of the through hole of the pure Mg ingot and the outer surface of the magnesium alloy rod in turn. After polishing, rinse with alcohol and then blow dry with a hair dryer;

[0060] S3, assembly and combination: the cleaned and air-dried pure Mg ingot and magnesium alloy rod are assembled and combined, firstly, the magnesium alloy rod is hammered into the hole of the ingot with a hammer; then, a hydraulic press or a hammer is used to apply pressure and slowly push it forward until the magnesium alloy rod is completely embedded in the ingot; then, the excess part of the magnesium alloy rod that is not embedded in the through hole is cut off, and this process is repeated to complete the assembly of all magnesium alloy rods, and a magnesium alloy composite rod blank is obtained;

[0061] S4. Extrusion molding: The magnesium alloy composite rod blank is placed in a resistance furnace for preheating at a temperature of 400°C for 1 hour, and then extruded in an extruder. The extrusion die is a rod die, the extrusion ratio is 28, and the extrusion speed is 10 m / min to obtain a magnesium alloy composite rod.

[0062] The mechanical properties of the Mg / Mg-2Y-0.6Zr composite rod prepared in this embodiment are as follows: room temperature tensile strength is 216 MPa, and elongation after fracture is 21%.

[0063] Embodiment 5

[0064] A method for preparing a magnesium alloy composite rod comprises the following steps.

[0065] S1. Material preparation and processing: prepare a Mg-2.6Er-0.6Zr magnesium alloy ingot with a diameter of 80 mm and a length of 100 mm, extrude it at 420°C into an extruded rod with a diameter of 16 mm for standby use, remove the surface of the rod, and obtain 6 extruded rods with a diameter of 15.5 mm and a length of 100 mm; prepare a pure Mg ingot with a diameter of 80 mm and a length of 80 mm, and evenly cut 6 through holes with a diameter of 15 mm on the end face of the pure Mg ingot at a circular position with a diameter of 40 mm, and the axial direction of the through hole is inclined at an angle of 30° to the axial direction of the pure Mg ingot;

[0066] S2. Surface cleaning: Use sandpaper from coarse to fine to polish the inner surface of the through hole of the pure Mg ingot and the outer surface of the magnesium alloy rod in turn. After polishing, rinse with alcohol and then blow dry with a hair dryer;

[0067] S3, assembly and combination: the cleaned and air-dried pure Mg ingot and magnesium alloy rod are assembled and combined, firstly, the magnesium alloy rod is hammered into the hole of the ingot with a hammer; then, a hydraulic press or a hammer is used to apply pressure and slowly push it forward until the magnesium alloy rod is completely embedded in the ingot; then, the excess part of the magnesium alloy rod that is not embedded in the through hole is cut off, and this process is repeated to complete the assembly of all magnesium alloy rods, and a magnesium alloy composite rod blank is obtained;

[0068] S4. Extrusion molding: The magnesium alloy composite rod blank is placed in a resistance furnace for preheating at a temperature of 420° C. for 1 hour, and then extruded in an extruder. The extrusion die is a rod die, the extrusion ratio is 28, and the extrusion speed is 10 m / min to obtain a magnesium alloy composite rod.

[0069] The mechanical properties of the Mg / Mg-2.6Er-0.6Zr composite rod prepared in this embodiment are as follows: room temperature tensile strength is 215 MPa, and elongation after fracture is 20%.

[0070] Embodiment 6

[0071] A method for preparing a magnesium alloy composite rod comprises the following steps.

[0072] S1. Material preparation and processing: prepare a Mg-2.6Er-0.6Zr magnesium alloy ingot with a diameter of 80mm and a length of 100mm, extrude it into an extruded rod with a diameter of 16mm at 420℃ for standby use, remove the surface of the rod, and obtain 6 extruded rods with a diameter of 15.5mm and a length of 100mm; prepare a pure Mg ingot with a diameter of 80mm and a length of 80mm, and evenly cut 6 blind holes with a diameter of 15mm on the end face of the pure Mg ingot at a circular position with a diameter of 40mm, and the axial direction of the blind hole is inclined at an angle of 30° to the axial direction of the pure Mg ingot; the bottom of the blind hole is parallel to the lower end face of the pure Mg ingot, and the bottom of the blind hole is 2mm away from the lower end face of the pure Mg ingot;

[0073] S2. Surface cleaning: Use sandpaper from coarse to fine to polish the inner surface of the through hole of the pure Mg ingot and the outer surface of the magnesium alloy rod in turn. After polishing, rinse with alcohol and then blow dry with a hair dryer;

[0074] S3, assembly and combination: the cleaned and air-dried pure Mg ingot and magnesium alloy rod are assembled and combined, firstly, the magnesium alloy rod is hammered into the hole of the ingot with a hammer; then, a hydraulic press or a hammer is used to apply pressure and slowly push it forward until the magnesium alloy rod is completely embedded in the ingot; then, the excess part of the magnesium alloy rod that is not embedded in the through hole is cut off, and this process is repeated to complete the assembly of all magnesium alloy rods, and a magnesium alloy composite rod blank is obtained;

[0075] S4. Extrusion molding: The magnesium alloy composite rod blank is placed in a resistance furnace for preheating at a temperature of 420° C. for 1 hour, and then extruded in an extruder. The extrusion die is a rod die, the extrusion ratio is 28, and the extrusion speed is 10 m / min to obtain a magnesium alloy composite rod.

[0076] The mechanical properties of the Mg / Mg-2.6Er-0.6Zr composite rod prepared in this embodiment are as follows: room temperature tensile strength is 215 MPa, and elongation after fracture is 20%.

[0077] Comparative Example 1

[0078] A method for preparing a magnesium alloy composite rod comprises the following steps.

[0079] S1. Material preparation and processing: prepare a Mg-2Gd-0.4Zr magnesium alloy ingot with a diameter of 80 mm and a length of 100 mm, extrude it at 420°C into an extruded rod with a diameter of 16 mm for standby use, remove the surface of the rod, and obtain 6 extruded rods with a diameter of 15.5 mm and a length of 100 mm; prepare a pure Mg ingot with a diameter of 80 mm and a length of 80 mm, and evenly cut 6 through holes with a diameter of 15 mm on the end face of the pure Mg ingot at a circular position with a diameter of 40 mm, and the axial direction of the through hole is inclined at an angle of 0° to the axial direction of the pure Mg ingot;

[0080] S2. Surface cleaning: Use sandpaper from coarse to fine to polish the inner surface of the through hole of the pure Mg ingot and the outer surface of the magnesium alloy rod in turn. After polishing, rinse with alcohol and then blow dry with a hair dryer;

[0081] S3, assembly and combination: the cleaned and air-dried pure Mg ingot and magnesium alloy rod are assembled and combined, firstly, the magnesium alloy rod is hammered into the hole of the ingot with a hammer; then, a hydraulic press or a hammer is used to apply pressure and slowly push it forward until the magnesium alloy rod is completely embedded in the ingot; then, the excess part of the magnesium alloy rod that is not embedded in the through hole is cut off, and this process is repeated to complete the assembly of all magnesium alloy rods, and a magnesium alloy composite rod blank is obtained;

[0082] S4. Extrusion molding: The magnesium alloy composite rod blank is placed in a resistance furnace for preheating at a temperature of 420° C. for 1 hour, and then extruded in an extruder. The extrusion die is a rod die, the extrusion ratio is 28, and the extrusion speed is 10 m / min to obtain a magnesium alloy composite rod.

[0083] In the magnesium alloy composite rod prepared in this comparative example, the two materials separated during stretching and no effective bonding was produced.

[0084] Comparative Example 2

[0085] A method for preparing a magnesium alloy composite rod comprises the following steps.

[0086] S1. Material preparation and processing: prepare a Mg-2Gd-0.4Zr magnesium alloy ingot with a diameter of 80 mm and a length of 100 mm, extrude it at 420°C into an extruded rod with a diameter of 16 mm for standby use, remove the surface of the rod, and obtain 6 extruded rods with a diameter of 15.5 mm and a length of 100 mm; prepare a pure Mg ingot with a diameter of 80 mm and a length of 80 mm, and evenly cut 6 through holes with a diameter of 15 mm on the end face of the pure Mg ingot at a circular position with a diameter of 40 mm, and the axial direction of the through hole is inclined at an angle of 0° to the axial direction of the pure Mg ingot;

[0087] S2. Surface cleaning: Use sandpaper from coarse to fine to polish the inner surface of the through hole of the pure Mg ingot and the outer surface of the magnesium alloy rod in turn. After polishing, rinse with alcohol and then blow dry with a hair dryer;

[0088] S3, assembly and combination: the cleaned and air-dried pure Mg ingot and magnesium alloy rod are assembled and combined, firstly, the magnesium alloy rod is hammered into the hole of the ingot with a hammer; then, a hydraulic press or a hammer is used to apply pressure and slowly push it forward until the magnesium alloy rod is completely embedded in the ingot; then, the excess part of the magnesium alloy rod that is not embedded in the through hole is cut off, and this process is repeated to complete the assembly of all magnesium alloy rods, and a magnesium alloy composite rod blank is obtained;

[0089] S4. Extrusion molding: The magnesium alloy composite rod blank is placed in a resistance furnace for preheating at a temperature of 420° C. for 1 hour, and then extruded in an extruder. The extrusion die is a rod die, the extrusion ratio is 85, and the extrusion speed is 10 m / min to obtain a magnesium alloy composite rod.

[0090] The mechanical properties of the magnesium alloy composite rod prepared in this comparative example are as follows: room temperature tensile strength is 202MPa, and elongation after fracture is 15%. Compared with Example 3, the extrusion ratio is the same, the axial inclination angle between the Mg-2Gd-0.4Zr magnesium alloy rod and the pure Mg ingot is 0°, and the room temperature tensile strength and elongation after fracture are lower than those of Example 3.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for preparing a magnesium alloy composite rod, characterized in that: The following steps are involved: S1. preparing a pure Mg ingot, and turning a plurality of holes from the end surface of the pure Mg ingot, wherein the axial direction of the holes forms a certain angle with the axial direction of the ingot; S2, preparing a plurality of Mg-RE-Zr alloy bars, and interference fitting the Mg-RE-Zr alloy bars into the holes of the pure Mg ingot in S1 to form a magnesium alloy composite bar blank; S3. Preheating and extruding the magnesium alloy composite rod blank obtained in S2 to obtain a magnesium alloy composite rod.

2. The preparation method according to claim 1, characterized in that: The RE in the Mg-RE-Zr alloy material in step S1 is one of Gd, Y, Er, Dy, Sm, and Tm.

3. The preparation method according to claim 2, characterized in that: The mass percentage of each element in the Mg-RE-Zr alloy material in step S1 is: RE 2.0%-5.0%, Zr 0.3%-1.0%, and the balance is Mg.

4. The preparation method according to claim 1, characterized in that: The hole in step S1 is a through hole or a blind hole.

5. The preparation method according to claim 4, characterized in that: The number of holes in step S1 is 4 to 8.

6. The preparation method according to claim 1, characterized in that: In step S1, the angle between the axial direction of the hole and the axial direction of the ingot is 5° to 85°.

7. The preparation method according to claim 1, characterized in that: In the step S2, the interference between the hole of the Mg-RE-Zr alloy rod and the pure Mg ingot is 0.5-0.8 mm.

8. The preparation method according to claim 1, characterized in that: The mass percentage of each material in the magnesium alloy composite rod in step S3 is: 8% to 50% of Mg-RE-Zr alloy material, and the rest is pure Mg.

9. The preparation method according to claim 1, characterized in that: The process parameters for preheating the magnesium alloy composite bar blank and extruding the bar in step S3 are: preheating temperature 300-480°C, preheating time 1-12h, extrusion temperature 300-480°C, extrusion ratio 8-85, and extrusion speed 5-30m / min.

10. A magnesium alloy composite rod prepared according to the preparation method according to any one of claims 1 to 9.

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