A high-toughness Mg-RE-Zn alloy rod with synchronous improvement of strength and plasticity and a preparation method thereof
Patent Information
- Application Number
- CN202610916275.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-24
- Publication Date
- 2026-10-16
AI Technical Summary
目前，研究发展出了稀土合金化技术，在镁中添加Gd、Y等稀土元素能产生显著的固溶强化效果，但过量的稀土元素固溶会严重损害合金的延展性，同时大量析出的第二相也会进一步恶化塑性，导致合金室温成形性能极差，加工过程中易产生裂纹
（1）本发明通过在选择在合金中添加稀土元素Gd、Y和过渡元素Zn元素，在合金中引入了大量的14H-LPSO相作为强化相。先通过热挤压-室温旋锻工艺，使得大块第二相的Mg-RE相发生应力集中破碎成颗粒，并通过颗粒诱导机制促进合金再结晶，同时在该工艺过程中可以形成弥散分布的β-Mg5(Gd,Y)第二相；层状LPSO相通过扭折机制协调变形，释放应力集中，从而抑制再结晶；细小的β-Mg5(Gd,Y)相则通过颗粒钉扎作用阻碍再结晶，这些因素综合作用导致双峰组织的形成，即本发明的制备方法，通过特定的组分，结合特定的工艺，使得生成包括具有双峰组织，14H-LPSO和大量的析出相Mg5(Gd,Y)的棒材，进而协同提高了合金的力学性能；时效过程中析出的纳米级β'相通过Orowan机制有效地钉扎了位错，额外贡献了显著的沉淀强化增量；在48小时的长时间保温过程中，材料发生了显著的回复过程。部分异号位错发生湮灭，位错胞壁锐化形成亚晶界，这有效地降低了基体内部的残余应力水平，释放了部分位错存储空间。这种因回复而软化的效应恰好被因析出而硬化的效应所覆盖，但在拉伸变形后期，降低了的位错密度使得材料能够容纳更多的塑性变形，从而延缓了颈缩和断裂，实现了延伸率的回升。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of metallic materials technology, and in particular to a high-strength and high-toughness Mg-RE-Zn alloy rod with simultaneous improvement in strength and plasticity, and its preparation method. Background Technology
[0002] Magnesium alloys, as a highly promising lightweight metallic structural material, possess high specific strength, high specific stiffness, good dimensional stability, excellent thermal and electrical conductivity, and superior casting and machining properties, demonstrating broad application prospects in aerospace, transportation, and 3C electronics fields. my country's abundant magnesium resources provide a solid material foundation for the development of the magnesium alloy industry.
[0003] However, traditional magnesium alloys suffer from drawbacks such as low absolute strength, poor plasticity, and inadequate corrosion resistance at room temperature, severely restricting their large-scale engineering applications. Therefore, the design and development of high-performance magnesium alloys has become a popular research direction. High-performance magnesium alloys are based on magnesium alloys, further improving their comprehensive properties through trace element alloying and multi-element alloying technologies, resulting in outstanding properties such as high strength and toughness, heat resistance, corrosion resistance, and flame retardancy. Currently, rare earth alloying technology has been developed, and adding rare earth elements such as Gd and Y to magnesium can produce significant solid solution strengthening effects. However, excessive rare earth element solid solution can severely impair the alloy's ductility, and the large amount of precipitated second phase can further deteriorate plasticity, leading to extremely poor room temperature formability and susceptibility to cracking during processing. How to improve strength while maintaining or even enhancing the alloy's plasticity is a pressing technical challenge in the field of magnesium alloy research. Summary of the Invention
[0004] The purpose of this invention is to provide a high-strength and high-toughness Mg-RE-Zn alloy rod and its preparation method, which simultaneously improves strength and plasticity. The method involves using Mg-RE-Zn alloy, extruding it into a rod, improving the strength of the alloy through rotary forging, and then aging treatment to further improve the strength and restore the plasticity, thereby obtaining a high-strength and high-toughness Mg-RE-Zn alloy rod.
[0005] To achieve the above objectives, the present invention provides a method for preparing high-strength and high-toughness Mg-RE-Zn alloy rods that simultaneously improve strength and plasticity, comprising the following steps: (1) Homogenize the Mg-RE-Zn alloy ingot with heat treatment; (2) The ingot processed in step (1) is preheated and then extruded to obtain extruded bars; (3) The extruded bar obtained in step (2) is subjected to rotary forging deformation treatment at room temperature to obtain rotary forged alloy bar; (4) The forged alloy bar obtained in step (3) is subjected to aging treatment to obtain a high-strength and high-toughness Mg-RE-Zn alloy bar.
[0006] Preferably, in step (1), the Mg-RE-Zn alloy ingot comprises, by weight percentage, 1-2% Zn, 10-15% RE, and the balance being Mg and unavoidable impurities; wherein RE is Gd and Y elements.
[0007] Preferably, the Mg-RE-Zn alloy also contains Zr and / or Mn elements.
[0008] Preferably, in step (1), the specific operation of the homogenization heat treatment is as follows: the alloy ingot is heated to 500°C and held for 8 hours, then heated to 520°C and held for 12 hours, and then air-cooled.
[0009] Preferably, in step (2), the preheating conditions are: preheating temperature of 440-460℃ and preheating time of 0.5-1.5h; the hot extrusion molding conditions are: extrusion ratio of 28:1, extrusion speed of 0.6mm / s and extrusion temperature of 440-460℃.
[0010] Preferably, in step (3), the specific operation of the rotary forging deformation treatment is as follows: the extruded bar is subjected to multi-pass rotary forging at room temperature, with a single pass reduction of 0.1 mm, 12-14 passes, a total reduction of 2-3 mm, and the bar diameter is reduced from 14-16 mm to 12-13 mm.
[0011] Preferably, in step (4), the aging process conditions are as follows: the forged alloy bar is aged at 190-210℃ for 40-50h, and then taken out and water-cooled.
[0012] The present invention also provides a high-strength and high-toughness Mg-RE-Zn alloy rod with simultaneously improved strength and plasticity obtained by the above preparation method.
[0013] Therefore, the high-strength and high-toughness Mg-RE-Zn alloy rod and its preparation method provided by the present invention have the following beneficial effects: (1) The present invention introduces a large amount of 14H-LPSO phase as a strengthening phase in the alloy by selecting rare earth elements Gd, Y and transition element Zn to add to the alloy. First, a hot extrusion-room temperature rotary forging process is used to cause stress concentration and break the bulk Mg-RE phase into particles, promoting alloy recrystallization through a particle-induced mechanism. Simultaneously, a dispersed β-Mg5(Gd,Y) second phase is formed during this process. The layered LPSO phase coordinates deformation through a torsion mechanism, releasing stress concentration and thus inhibiting recrystallization. The fine β-Mg5(Gd,Y) phase hinders recrystallization through particle pinning. The combined effect of these factors leads to the formation of a bimodal structure. This invention's preparation method, through specific components and a specific process, produces rods containing a bimodal structure, 14H-LPSO, and a large amount of precipitated Mg5(Gd,Y), thereby synergistically improving the alloy's mechanical properties. During aging, the nanoscale β' phase precipitated effectively pins dislocations through the Orowan mechanism, contributing a significant additional precipitation strengthening increment. During a long-term holding period of 48 hours, the material undergoes a significant recovery process. Some dislocations with opposite signs annihilate, and the dislocation cell walls sharpen to form subgrain boundaries. This effectively reduces the residual stress level inside the matrix and releases some dislocation storage space. This softening effect due to recovery is exactly covered by the hardening effect due to precipitation. However, in the later stages of tensile deformation, the reduced dislocation density allows the material to accommodate more plastic deformation, thereby delaying necking and fracture and achieving a recovery in elongation.
[0014] (2) The Mg-RE-Zn alloy rods prepared by the present invention have excellent mechanical properties at room temperature, with a tensile strength of 538 MPa, a yield strength of 468 MPa and an elongation of 9.9%. The comprehensive mechanical properties are excellent, overcoming the defects of poor plasticity of traditional high-strength rare earth magnesium alloys.
[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0016] Figure 1 The image shows an optical microscope (OM) image of the high-strength and high-toughness Mg-RE-Zn alloy prepared in Example 2 of the present invention; wherein, (a) shows the bimodal characteristics of the microstructure at low magnification, and (b) shows the LPSO phase twisting and second phase fragmentation at high magnification. Figure 2 The image shows a scanning electron microscope (SEM) image of the high-strength and high-toughness Mg-RE-Zn alloy prepared in Example 2 of the present invention; wherein, (a) is the morphology of the broken and twisted LPSO phase, and (b) is the distribution diagram of the diffusely distributed second phase. Figure 3The room temperature tensile stress-strain curve of the high-strength and high-toughness Mg-RE-Zn alloy prepared in Example 1 of this invention is shown. Figure 4 The image shows the room temperature tensile stress-strain curve of the high-strength and high-toughness Mg-RE-Zn alloy prepared in Example 2 of this invention. Detailed Implementation
[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.
[0018] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.
[0019] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.
[0020] When a quantity, concentration, or other value or parameter is described as a range, preferred range, or preferred upper and lower limits, it should be understood that it is equivalent to specifically disclosing any range by combining any pair of upper or preferred values with any lower or preferred values, regardless of whether the range is specifically disclosed. Unless otherwise stated, the numerical range values listed herein include the endpoints of the range and all integers and fractions within that range.
[0021] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art, and the testing standards all use national or international standards commonly used in the field, without further explanation.
[0022] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.
[0023] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.
[0024] In the following examples, the Mg-RE-Zn raw materials are Mg-8.9Gd-3.9Y-1.3Zn-0.8Mn and Mg-6Gd-5Y-1Zn-0.4Zr, which can be obtained through commercial purchases or conventional methods.
[0025] The stretching machine used in this embodiment of the invention is a UTM4104. The metallurgical microscope used in this embodiment of the invention is an OLYMPUS PMG3. The scanning electron microscope used in this embodiment of the invention is a FEI NOVA 400. The heat treatment furnace used in this embodiment of the invention is model DZF-6050BZ.
[0026] Example 1 This embodiment provides a method for preparing high-strength and high-toughness Mg-RE-Zn alloy rods with simultaneous improvement in strength and ductility. The chemical composition of the alloy ingot, by weight percentage, is: Zn 1.3%, Gd 8.9%, Y 3.9%, Mn 0.8%, with the balance being Mg and unavoidable impurities. The specific steps include: (1) Homogenization heat treatment: The above Mg-RE-Zn alloy ingot is placed in a heat treatment furnace, heated to 500℃ and held for 8 hours, then heated to 520℃ and held for 12 hours, and then taken out and air-cooled to room temperature to obtain a homogenized ingot.
[0027] (2) Preheating and extrusion molding: The homogenized ingot obtained in step (1) is preheated at 450℃ for 1 hour. Then the preheated ingot is placed in an extruder for hot extrusion molding. The extrusion temperature is 450℃, the extrusion ratio is 28:1, and the extrusion speed is 0.6mm / s to obtain extruded bars.
[0028] (3) Room temperature rotary forging deformation treatment: The extruded bar obtained in step (2) is placed in a rotary forging machine at room temperature and multi-pass rotary forging is performed with a single pass reduction of 0.1 mm. The number of rotary forging passes is 13, the total reduction is 1.3 mm, and the bar diameter is reduced from 16.0 mm to 13.4 mm to obtain a rotary forged alloy bar.
[0029] (4) Aging treatment: The forged alloy bar obtained in step (3) is placed in a heat treatment furnace and heated to 200°C. It is then kept at that temperature for 48 hours and then taken out and water-cooled to obtain a high-strength and high-toughness Mg-RE-Zn alloy bar.
[0030] Example 2 This embodiment provides a method for preparing high-strength and high-toughness Mg-RE-Zn alloy rods with simultaneous improvement in strength and ductility. The chemical composition of the alloy ingot, by weight percentage, is: Zn 1.0%, Gd 6.0%, Y 5.0%, Zr 0.4%, with the balance being Mg and unavoidable impurities. The method specifically includes the following steps: (1) Homogenization heat treatment: The above Mg-RE-Zn alloy ingot is placed in a heat treatment furnace, heated to 500℃ and held for 8 hours, then heated to 520℃ and held for 12 hours, and then taken out and air-cooled to room temperature to obtain a homogenized ingot.
[0031] (2) Preheating and extrusion molding: The homogenized ingot obtained in step (1) is preheated at 450℃ for 1 hour. Then the preheated ingot is placed in an extruder for hot extrusion molding. The extrusion temperature is 450℃, the extrusion ratio is 28:1, and the extrusion speed is 0.6mm / s to obtain extruded bars.
[0032] (3) Room temperature rotary forging deformation treatment: The extruded bar obtained in step (2) is placed in a rotary forging machine at room temperature and multi-pass rotary forging is performed with a single pass reduction of 0.1 mm. The number of rotary forging passes is 13, the total reduction is 1.3 mm, and the bar diameter is reduced from 16.0 mm to 13.4 mm to obtain a rotary forged alloy bar.
[0033] (4) Aging treatment: The forged alloy bar obtained in step (3) is placed in a heat treatment furnace and heated to 200°C. It is then kept at that temperature for 48 hours and then taken out and water-cooled to obtain a high-strength and high-toughness Mg-RE-Zn alloy bar.
[0034] Characterization and performance testing: This application describes the morphology and performance of the prepared high-strength and high-toughness Mg-RE-Zn alloy, specifically as follows: 1) Organizational morphology characterization Test method: Because the morphologies of Examples 1 and 2 are similar, this test example only provides the microstructure characterization diagram of the high-strength and tough Mg-RE-Zn alloy prepared in Example 2, based on its OM diagram ( Figure 1 ) and SEM image ( Figure 2 It can be seen that the microstructure of the alloy after hot extrusion-room temperature rotary forging deformation-aging treatment underwent significant changes. The bulk Mg-RE phase of the second phase underwent stress concentration and broke into particles, promoting the recrystallization of the alloy through a particle-induced mechanism. At the same time, a dispersed β-Mg5(Gd,Y) second phase can be formed during the extrusion-rotary forging process. The layered LPSO phase coordinates the deformation through a torsion mechanism, releases stress concentration, and thus inhibits recrystallization. The fine β-Mg5(Gd,Y) phase hinders recrystallization through particle pinning. The combined effect of these factors leads to the formation of a bimodal microstructure. After aging, a dense β' phase precipitated on the basal surface.
[0035] 2) Mechanical property testing Test method: The mechanical properties of the high-strength and high-toughness Mg-RE-Zn alloys prepared in Example 1 and Example 2 were tested using a UTM4104 testing machine. The test results are as follows: Figures 3-4 And as shown in Tables 1 and 2.
[0036] Table 1: Mechanical properties of Mg-8.9Gd-3.9Y-1.3Zn-0.8Mn alloy in different states
[0037] Table 2: Mechanical properties of Mg-6Gd-5Y-1Zn-0.4Zr alloy under different conditions
[0038] from Figures 3-4 As shown in Tables 1 and 2, the Mg-RE-Zn alloy of the present invention exhibits significantly improved strength and elongation after aging. The Mg-RE-Zn alloy prepared by the method of the present invention possesses excellent strength and toughness. In Example 1, the tensile strength of the alloy increased from 475 MPa to 539 MPa, an increase of 64 MPa; the yield strength increased from 453 MPa to 469 MPa; and the elongation recovered from 6.0% to 6.8%. In Example 2, the tensile strength of the alloy increased from 462 MPa to 538 MPa, an increase of 76 MPa; the yield strength increased from 443 MPa to 468 MPa; and the elongation recovered from 6.5% to 9.9%. The ultra-high strength after aging stems from the combined effect of rotary forging hardening and precipitation strengthening. The high-density dislocations and extremely fine fibrous grains remaining from rotary forging provide the strength base; while the nanoscale β' phase precipitated during aging effectively pins the dislocations through the Orowan mechanism, contributing an additional significant increase in precipitation strengthening. Normally, aging precipitation hinders dislocation movement, thus reducing plasticity. However, the synergistic enhancement observed in this study may be due to the extremely high distortion energy and saturated dislocation density stored within the forged material, leading to the depletion of its deformation capacity. During the 48-hour long-term holding period, the material underwent a significant recovery process. Some dislocations of opposite signs annihilated, and the dislocation cell walls sharpened to form subgrain boundaries, effectively reducing the residual stress level within the matrix and releasing some dislocation storage space. This softening effect due to recovery was precisely offset by the hardening effect due to precipitation. However, in the later stages of tensile deformation, the reduced dislocation density allowed the material to accommodate more plastic deformation, thereby delaying necking and fracture, and achieving a recovery in elongation.
[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing high-strength and high-toughness Mg-RE-Zn alloy rods with simultaneous improvement in strength and plasticity, characterized in that, Includes the following steps: (1) Homogenize the Mg-RE-Zn alloy ingot with heat treatment; (2) The ingot processed in step (1) is preheated and then extruded to obtain extruded bars; (3) The extruded bar obtained in step (2) is subjected to rotary forging deformation treatment at room temperature to obtain rotary forged alloy bar; (4) The forged alloy bar obtained in step (3) is subjected to aging treatment to obtain a high-strength and high-toughness Mg-RE-Zn alloy bar.
2. The method for preparing high-strength and high-toughness Mg-RE-Zn alloy rods with simultaneous improvement in strength and plasticity according to claim 1, characterized in that, In step (1), the Mg-RE-Zn alloy ingot, by weight percentage, includes Zn: 1-2%, RE: 10-15%, with the balance being Mg and unavoidable impurities; wherein RE is Gd and Y elements.
3. The method for preparing a high-strength and high-toughness Mg-RE-Zn alloy rod with simultaneous improvement in strength and plasticity according to claim 2, characterized in that, Mg-RE-Zn alloys also contain Zr and / or Mn elements.
4. The method for preparing high-strength and high-toughness Mg-RE-Zn alloy rods with simultaneous improvement in strength and plasticity according to claim 1, characterized in that, In step (1), the specific operation of homogenization heat treatment is as follows: the alloy ingot is heated to 500℃ and held for 8 hours, then heated to 520℃ and held for 12 hours, and then air-cooled.
5. The method for preparing high-strength and high-toughness Mg-RE-Zn alloy rods with simultaneous improvement in strength and plasticity according to claim 1, characterized in that, In step (2), the preheating conditions are: preheating temperature of 440-460℃ and preheating time of 0.5-1.5h; the hot extrusion molding conditions are: extrusion ratio of 28:1, extrusion speed of 0.6mm / s and extrusion temperature of 440-460℃.
6. The method for preparing high-strength and high-toughness Mg-RE-Zn alloy rods with simultaneous improvement in strength and plasticity according to claim 1, characterized in that, In step (3), the specific operation of the rotary forging deformation treatment is as follows: the extruded bar is subjected to multi-pass rotary forging at room temperature, with a single pass reduction of 0.1 mm, 12-14 passes, a total reduction of 2-3 mm, and the bar diameter is reduced from 14-16 mm to 12-13 mm.
7. The method for preparing high-strength and high-toughness Mg-RE-Zn alloy rods with simultaneous improvement in strength and plasticity according to claim 1, characterized in that, In step (4), the aging process conditions are as follows: the forged alloy bar is aged at 190-210℃ for 40-50h, and then taken out and water-cooled.
8. A high-strength, high-toughness Mg-RE-Zn alloy bar that simultaneously improves strength and plasticity, characterized in that, The alloy rod is prepared by the preparation method described in any one of claims 1-7.