High-strength and high-plasticity Mg-Gd-Zn alloy bar and preparation method thereof
By controlling the Zn content and optimizing the process, high-strength and plastic Mg-Gd-Zn alloy rods are prepared, which solves the problem of strength attenuation under large diameter, achieves high performance and large-scale production, and reduces rare earth element loss and production costs.
Patent Information
- Application Number
- CN202511001829.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-21
- Publication Date
- 2025-09-16
AI Technical Summary
The existing Mg-Gd-Zn alloy rods have severe strength attenuation at large diameters, which makes it difficult to meet the high performance and large-scale requirements of high-end equipment. In addition, the ineffective loss of rare earth elements and the effect of thermomechanical treatment are limited.
By controlling the Zn content at 0.1-0.6wt.%, the Gd to Zn mass ratio greater than 20, and combining the low-temperature, small extrusion ratio reverse extrusion process with rapid induction heating and cold water quenching, high-strength and plastic Mg-Gd-Zn alloy bars are prepared to avoid the formation of refractory phases and optimize the microstructure.
The high-strength and plastic Mg-Gd-Zn alloy rods have achieved a yield strength of ≥320MPa, a tensile strength of ≥380MPa, and an elongation of ≥10%, breaking through the existing diameter limitations, meeting the needs of high-end equipment, reducing rare earth element loss, and lowering production costs.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of alloy material preparation, and particularly relates to a high-strength and plastic Mg-Gd-Zn alloy bar and a preparation method thereof. Background Art
[0002] As a lightweight engineering structural material with great development potential, magnesium alloy has important strategic value in weight reduction applications in aerospace, national defense, military industry, rail transportation and other fields. However, its inherent defect of low absolute engineering strength has seriously restricted its large-scale engineering application. In recent years, rare earth magnesium alloys with mixed crystal structure characteristics have become an international research hotspot. Such alloys can improve the comprehensive mechanical properties through microstructure regulation. However, existing research shows that the diameter of high-performance mixed crystal structure rare earth magnesium alloy extruded bars is generally limited to less than 20 mm, and there is a significant strength attenuation phenomenon with increasing diameter, which makes it difficult to meet the demand for the coordinated development of "high performance-large scale" of magnesium alloy components in my country's high-end equipment field.
[0003] Furthermore, the Zn addition in traditional Mg-Gd-Zn alloy systems usually exceeds 1wt.%. This composition design easily leads to the formation of (Mg,Zn)3Gd crystalline phases and long-period ordered structures (LPSO phases) with high thermal stability. These (Mg,Zn)3Gd compounds are difficult to fully dissolve back during solution treatment, which not only causes ineffective loss of expensive rare earth elements, but also seriously weakens the second phase strengthening effect during subsequent thermomechanical treatment, resulting in limited improvement in alloy performance. Therefore, how to regulate the alloy composition to avoid the formation of insoluble phases and optimize the processing technology to achieve large-scale components while ensuring high strength and plasticity of the alloy has become a technical problem that needs to be solved in this field. Summary of the Invention
[0004] The present invention aims to provide a high-strength and plastic Mg-Gd-Zn alloy rod and a preparation method thereof. The high-strength and plastic Mg-Gd-Zn alloy rod has excellent comprehensive properties, a yield strength exceeding 320 MPa and / or a tensile strength exceeding 380 MPa, and an elongation exceeding 10%.
[0005] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:
[0006] A high-strength and plastic Mg-Gd-Zn alloy bar comprises the following alloy components by mass percentage: Gd 13%-15%, Zn 0.1%-0.6%, and the remainder is Mg and unavoidable impurities, wherein the mass ratio of Gd to Zn is greater than 20.
[0007] The present invention also provides a method for preparing a high-strength and high-plasticity Mg-Gd-Zn alloy bar, comprising the following steps:
[0008] S1. Select high-purity magnesium, high-purity gadolinium, and high-purity zinc as raw materials;
[0009] S2, preparing Mg-30Gd master alloy;
[0010] S3, preparing Mg-Gd-Zn alloy ingot;
[0011] S4, solution treatment: subjecting the Mg-Gd-Zn alloy ingot prepared in S3 to high temperature insulation treatment, quenching with hot water after the insulation is completed, and then quenching with cold water after the boiling stops;
[0012] S5. Processing the Mg-Gd-Zn alloy ingot treated in S4 into an extrusion billet, performing rapid induction heating, reverse extrusion, and immediately cold quenching to room temperature after extrusion to obtain a high-strength and high-plasticity Mg-Gd-Zn alloy rod.
[0013] Preferably, in S2, the Gd content in the Mg-30Gd master alloy is 30 wt.%.
[0014] Preferably, in S3, the Mg-Gd-Zn alloy ingot is melted by semi-continuous casting technology, and the alloy composition is detected by inductively coupled plasma emission spectroscopy to ensure that the alloy composition is accurate and the impurity content does not exceed the standard.
[0015] Preferably, the casting temperature is 680-700° C., the molten metal is cooled in the crystallizer, and ingots are taken out intermittently.
[0016] Preferably, in S4, the high-temperature insulation treatment temperature is 510-525°C, the high-temperature insulation treatment time is 20-30h, and the quenching hot water temperature is above 80°C.
[0017] Preferably, in S5, the rapid induction heating temperature is 310-330° C., and the rapid induction heating time does not exceed 5 minutes.
[0018] Preferably, in S5, the extrusion temperature is 300-320° C., the extrusion ratio is 4-9, and the extrusion speed is 0.1-1 mm / s.
[0019] Compared with the prior art, the present invention has the following advantages and technical effects:
[0020] 1. The present invention discloses a high-strength and high-plasticity Mg-Gd-Zn alloy bar and a preparation method thereof. The Zn content is controlled within a range of 0.1-0.6 wt.%, and the mass ratio of Gd to Zn is greater than 20. This avoids the formation of (Mg, Zn)3Gd phase and LPSO phase in traditional Mg-Gd-Zn alloys. After solution treatment, a single magnesium-based solid solution is obtained, ensuring sufficient Gd solute concentration during subsequent hot working. This lays the foundation for the uniform precipitation of nano-β-Mg5Gd precipitates during extrusion, significantly enhancing the second-phase strengthening effect.
[0021] 2. The present invention discloses a high-strength and high-plasticity Mg-Gd-Zn alloy rod and its preparation method. The invention adopts a low-temperature, small extrusion ratio reverse extrusion process, combined with rapid induction heating and immediate cold water quenching, to effectively suppress the extrusion temperature rise, obtain a mixed crystal structure with fine dynamically recrystallized grains, and form high-density stacking faults and nano-β-Mg5Gd precipitates inside the unrecrystallized grains, thereby achieving the synergistic effect of grain refinement strengthening and precipitation strengthening.
[0022] 3. The present invention discloses a high-strength and plastic Mg-Gd-Zn alloy rod and a preparation method thereof. The high-strength and plastic Mg-Gd-Zn alloy rod has a yield strength ≥320 MPa, a tensile strength ≥380 MPa, and an elongation ≥10%, breaking through the strength limitation of existing rods with a diameter of less than 20 mm. Through composition and process optimization, larger diameter components can be prepared, meeting the application requirements of high-end equipment for high-performance and large-scale magnesium alloys, while reducing rare earth element loss and lowering production costs.
[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a transmission electron micrograph of the high-strength and plastic Mg-14Gd-0.2Zn alloy rod provided in Example 1, wherein: Figure 1 (a) shows the dynamic precipitation of recrystallized and non-recrystallized regions, with a scale of 200 nm. Figure 1 (b) is the dynamic precipitation inside the unrecrystallized grains, the scale is 200nm, Figure 1 (c) in the figure shows the stacking fault inside the unrecrystallized grain, with a scale of 200 nm.
[0025] Figure 2 The inverse pole figure and pole figure of the high-strength and plastic Mg-14Gd-0.2Zn alloy rod provided in Example 1, wherein: Figure 2 (a) is the inverse pole figure, Figure 2 (b) in the figure is the extreme figure;
[0026] Figure 3The inverse pole figure and pole figure of the Mg-14Gd-0.2Zn alloy rod provided in Comparative Example 1, wherein: Figure 3 (a) is the inverse pole figure, Figure 3 (b) in the figure is the extreme figure;
[0027] Figure 4 The room temperature tensile stress-strain curve of the high-strength and plastic Mg-14Gd-0.2Zn alloy bar provided in Example 1;
[0028] Figure 5 Room temperature tensile stress-strain curve of the Mg-14Gd-0.2Zn alloy rod provided in Comparative Example 1. DETAILED DESCRIPTION
[0029] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.
[0030] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.
[0031] Source of experimental materials: The Mg-30Gd master alloy in the examples of the present invention was prepared by Baotou Rare Earth Research Institute.
[0032] In the present invention, unless otherwise specified, other experimental raw materials and consumables are conventional experimental materials in the field and can be purchased through commercial channels.
[0033] Example 1
[0034] A method for preparing a high-strength and high-plasticity Mg-Gd-Zn alloy rod comprises the following steps:
[0035] S1. Select high-purity magnesium, high-purity gadolinium, and high-purity zinc as raw materials;
[0036] S2, preparing a Mg-30Gd master alloy, wherein the Gd content is 30 wt.%;
[0037] S3. Semi-continuous casting of Mg-14Gd-0.2Zn alloy ingots at a casting temperature of 680°C. The molten metal is cooled in the mold, and the ingots are removed intermittently. The alloy composition is tested using inductively coupled plasma emission spectroscopy to ensure that the alloy composition is accurate and the impurity content does not exceed the standard.
[0038] S4, solution treatment: subjecting the Mg-14Gd-0.2Zn alloy ingot prepared in S3 to a high-temperature holding treatment at 520°C for 24 hours, and then quenching in hot water above 80°C after the holding is completed;
[0039] S5. The Mg-14Gd-0.2Zn alloy ingot treated in S4 was turned into a billet with an extrusion size of Φ100mm×130mm, and was rapidly induction heated at 310℃ for no more than 5min. It was extruded at 300℃ with an extrusion ratio of 7 and an extrusion speed of 0.35mm / s. After completion, it was cold-quenched to room temperature to obtain a high-strength and high-plasticity Mg-14Gd-0.2Zn alloy rod.
[0040] Example 2
[0041] A method for preparing a high-strength and high-plasticity Mg-Gd-Zn alloy rod comprises the following steps:
[0042] S1. Select high-purity magnesium, high-purity gadolinium, and high-purity zinc as raw materials;
[0043] S2, preparing Mg-30Gd master alloy, wherein the Gd content is 30wt.%;
[0044] S3. Semi-continuous casting of Mg-15Gd-0.1Zn alloy ingots at a casting temperature of 690°C. The molten metal is cooled in the mold, and the ingots are removed intermittently. The alloy composition is tested using inductively coupled plasma emission spectroscopy to ensure that the alloy composition is accurate and the impurity content does not exceed the standard.
[0045] S4, solution treatment: subjecting the Mg-15Gd-0.1Zn alloy ingot prepared in S3 to a high-temperature holding treatment at 520°C for 24 hours, and then quenching in hot water above 80°C after the holding is completed;
[0046] S5. The Mg-15Gd-0.1Zn alloy ingot treated in S4 was turned into a billet with an extrusion size of Φ100mm×130mm, and was rapidly induction heated at 330℃ for no more than 5min, and extruded at 320℃ with an extrusion ratio of 7 and an extrusion speed of 0.3mm / s. After extrusion, it was cold-quenched to room temperature to obtain a high-strength and high-plasticity Mg-15Gd-0.1Zn alloy rod.
[0047] Comparative Example 1
[0048] A method for preparing a high-strength and high-plasticity Mg-Gd-Zn alloy rod comprises the following steps:
[0049] S1. Select high-purity magnesium, high-purity gadolinium, and high-purity zinc as raw materials;
[0050] S2, preparing Mg-30Gd master alloy, wherein the Gd content is 30wt.%;
[0051] S3. Semi-continuous casting of Mg-14Gd-0.2Zn alloy ingots at a casting temperature of 680°C. The molten metal is cooled in the mold, and the ingots are removed intermittently. The alloy composition is tested using inductively coupled plasma emission spectroscopy to ensure that the alloy composition is accurate and the impurity content does not exceed the standard.
[0052] S4, solution treatment: subjecting the Mg-14Gd-0.2Zn alloy ingot prepared in S3 to a high-temperature holding treatment at 520°C for 24 hours, and then quenching in hot water above 80°C after the holding is completed;
[0053] S5. The Mg-14Gd-0.2Zn alloy ingot treated in S4 was turned into a billet with an extrusion size of Φ100mm×130mm, and was rapidly induction heated at 330℃ for no more than 5min, and extruded at 320℃ with an extrusion ratio of 16 and an extrusion speed of 0.32mm / s. After extrusion, the billet was cold-quenched to room temperature to obtain a Mg-14Gd-0.2Zn alloy rod.
[0054] The effects of the high-strength and high-plasticity Mg-Gd-Zn alloy rod prepared in Example 1 and the Mg-14Gd-0.2Zn alloy rod provided in Comparative Example 1 were verified by the following experiments.
[0055] 1. The high strength and plasticity Mg-14Gd-0.2Zn alloy bar provided in Example 1 was characterized by the following test method: The microstructure was characterized by transmission electron microscopy. Figure 1 .
[0056] Depend on Figure 1 It can be seen that a large amount of massive dynamically precipitated β-Mg5Gd (with a size less than 100 nm) and high-density stacking faults are formed in the unrecrystallized grains.
[0057] 2. The inverse pole figures and pole figures of the high strength and plasticity Mg-Gd-Zn alloy rod provided in Example 1 and the Mg-14Gd-0.2Zn alloy rod provided in Comparative Example 1 were tested, and the grain and texture characteristics were characterized by electron backscatter diffraction technology. The results are as follows: Figure 2 and Figure 3 .
[0058] Depend on Figure 2 The high-strength and plastic Mg-Gd-Zn alloy rod produced in Example 1 exhibits a mixed crystal structure with a moderate recrystallization ratio and an average recrystallized grain size of approximately 1.25 μm. The recrystallized regions exhibit a random texture, while the unrecrystallized regions exhibit a stronger basal texture. The coarse unrecrystallized grains are separated by twin boundaries, and twinning deformation plays a significant role in the extrusion process, resulting in a weak overall texture in the alloy.
[0059] Depend on Figure 3As can be seen, the Mg-14Gd-0.2Zn alloy bar provided in Comparative Example 1 shows a significant increase in the proportion of recrystallized grains, an increase in size, and a weakened texture as the extrusion ratio increases. Furthermore, a larger extrusion ratio results in a relatively high temperature rise during extrusion, and the higher actual sample temperature causes grain growth and coarsening of the precipitated phase. Furthermore, a higher sample temperature reduces the supersaturation of the α-Mg solid solution matrix, resulting in a lower volume fraction of dynamic precipitation.
[0060] 3. Test strain rate 10 -3 s -1 The room temperature tensile test results of the high strength and plasticity Mg-Gd-Zn alloy rod provided in Example 1 and the Mg-14Gd-0.2Zn alloy rod provided in Comparative Example 1 are as follows: Figure 4 and Figure 5 .
[0061] Depend on Figure 4 It can be seen that the alloy exhibits excellent strength-plasticity synergy, with a yield strength of 328 MPa, a tensile strength of 385 MPa, and an elongation of 10.6%.
[0062] Depend on Figure 5 It can be seen that as the extrusion ratio increases, although the plasticity of the alloy increases, its strength decreases significantly, and its yield strength is lower than 300 MPa.
[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A high-strength and high-plasticity Mg-Gd-Zn alloy bar, characterized in that: The alloy composition is calculated by mass percentage as follows: Gd 13%-15%, Zn 0.1%-0.6%, and the balance is Mg and unavoidable impurities, wherein the mass ratio of Gd to Zn is greater than 20.
2. The method for preparing a high-strength and high-plasticity Mg-Gd-Zn alloy rod according to claim 1, characterized in that: The steps include: S1. Select high-purity magnesium, high-purity gadolinium, and high-purity zinc as raw materials; S2, preparing Mg-30Gd master alloy; S3, preparing Mg-Gd-Zn alloy ingot; S4, solution treatment: subjecting the Mg-Gd-Zn alloy ingot prepared in S3 to high temperature insulation treatment, quenching with hot water after the insulation is completed, and then quenching with cold water after the boiling stops; S5. Processing the Mg-Gd-Zn alloy ingot treated in S4 into an extrusion billet, performing rapid induction heating, reverse extrusion, and immediately cold quenching to room temperature after extrusion to obtain a high-strength and high-plasticity Mg-Gd-Zn alloy rod.
3. The preparation method according to claim 2, characterized in that: In S2, the Gd content in the Mg-30Gd master alloy is 30 wt.%.
4. The preparation method according to claim 2, characterized in that In S4, the high temperature insulation treatment temperature is 510-525°C, the high temperature insulation treatment time is 20-30 hours, and the quenching hot water temperature is above 80°C.
5. The preparation method according to claim 2, characterized in that: In S5, the rapid induction heating temperature is 310-330° C., and the rapid induction heating time does not exceed 5 minutes.
6. The preparation method according to claim 2, characterized in that: In S5, the extrusion temperature is 300-320° C., the extrusion ratio is 4-9, and the extrusion speed is 0.1-1 mm / s.