Method for preparing nanocrystalline-quasicrystal reinforced Mg-Zn-Y-Nd alloy by semi-solid stress quenching and hot deformation

Abstract

A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloys through a two-stage extrusion process comprises the following steps: A) Preparing a cast Mg-Zn-Y-Nd alloy according to a predetermined mass percentage ratio of each constituent element; B) Annealing the cast Mg-Zn-Y-Nd alloy at 360-430℃ for 10-20 hours, followed by furnace cooling; C) Holding the annealed Mg-Zn-Y-Nd alloy at a certain temperature before hot extrusion; D) Placing the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C in an electromagnetic induction heating furnace for stress quenching; E) Holding the Mg-Zn-Y-Nd alloy obtained in step D at a certain temperature, followed by secondary hot deformation; F) Aging at 160-220℃ for 10-40 hours to obtain the final product. This method can prepare high-performance magnesium alloys with excellent yield strength, tensile strength, and elongation, and is less prone to cracking during water quenching, which is beneficial for industrial production.

Description

Technical Field

[0001] This invention relates to a method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloys by a combination of semi-solid stress quenching and hot deformation, belonging to the field of magnesium alloy manufacturing, and particularly to the field of high-strength and high-toughness magnesium alloy preparation. Background Technology

[0002] Magnesium alloys, as the lightest metallic structural materials, also possess advantages such as high specific strength, good noise and vibration reduction, good electromagnetic shielding, and easy recyclability, making them promising for applications in transportation vehicles, aerospace, electronics and communications, and defense technology. In particular, with increasingly stringent requirements for lightweight, energy-saving, environmentally friendly, and ecologically sound transportation equipment, the application of magnesium alloys in this field is receiving growing attention. However, inherent drawbacks of magnesium alloys, such as relatively low strength and poor toughness, limit their widespread industrial application. Therefore, to further expand the application range of magnesium alloys and meet their needs in high-tech fields, it is essential to improve their overall performance.

[0003] Quasicrystalline phases possess excellent mechanical and physical properties due to their unique atomic arrangement, such as high strength, low coefficient of friction, oxidation resistance, and corrosion resistance. Introducing them as reinforcing phases into magnesium alloys can improve their overall performance, providing a new approach for the development and practical application of novel magnesium alloys. In recent years, the presence of quasicrystalline phases in the microstructure of Mg-Zn-Y alloys has become a research hotspot. Scholars from various countries have conducted extensive research on the composition design, preparation methods, and mechanical and physical properties of Mg-Zn-Y quasicrystalline alloys.

[0004] The production process of quasicrystalline reinforced Mg-Zn-Y alloys mainly includes casting and plastic processing. In the as-cast microstructure of quasicrystalline reinforced Mg-Zn-RE alloys, the quasicrystalline phase I-phase is mainly distributed in the form of lamellar eutectic crystals between the pre-solidified α-Mg dendrites. After plastic processing, the lamellar quasicrystalline phase I-phase is fragmented into small particles dispersed on the α-Mg matrix, acting as a reinforcing phase to improve the mechanical properties of Mg-Zn-Y alloys.

[0005] The particle size and distribution of quasicrystalline I-phase particles have a significant impact on the mechanical properties of Mg-Zn-Y alloys. Refining the quasicrystalline phase particles dispersed in the α-Mg matrix can improve the strengthening effect of the quasicrystalline phase, resulting in quasicrystalline reinforced Mg-Zn-Y alloys with excellent performance and lower cost.

[0006] Currently, the quasicrystalline I-phase particles in quasicrystalline reinforced Mg-Zn-Y alloys are mostly micrometer-sized, while research on nanoscale quasicrystalline I-phase particles reinforcing Mg-Zn-Y alloys is limited, and existing technologies struggle to further refine the size of these particles. To obtain quasicrystalline reinforced Mg-Zn-Y alloys with excellent mechanical properties, existing methods increase the quasicrystalline I-phase content by increasing the Zn and Y content. However, increasing the Zn and Y content leads to a decrease in elongation and significantly increases alloy costs. Existing methods also achieve nanoscale quasicrystalline lamellars through semi-solid treatment, followed by hot extrusion to transform them into nanoparticles. However, during semi-solid quenching, the billet is prone to cracking, making direct industrial application difficult. In practical applications, magnesium alloys require excellent comprehensive mechanical properties; therefore, developing high-performance magnesium alloys with excellent yield strength, tensile strength, and elongation suitable for industrial production, along with their processing technologies, is an urgent problem to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloys through a combination of semi-solid stress quenching and hot deformation. This method can prepare high-performance magnesium alloys with excellent yield strength, tensile strength, and elongation.

[0008] The technical solution adopted by this invention to achieve its objective is: a method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, the steps of which are as follows:

[0009] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 2.5-11% Zn, 0.5-2.5% Y, 0.05-1% Nd, and the remainder is Mg;

[0010] B. Anneal the as-cast Mg-Zn-Y alloy prepared in step A at 360-430℃ for 10-20h, and then cool it in the furnace.

[0011] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 300-380℃ for 2-4 hours, it is hot extruded at an extrusion temperature of 300-380℃ and an extrusion ratio of 9-80:1.

[0012] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 500-560℃, hold it for 0-20 minutes, and then perform stress quenching treatment.

[0013] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 300-380℃ for 2-4 hours, perform a second hot deformation. The specific operation of the second hot deformation is as follows: the second hot deformation temperature is 300-380℃ and the extrusion ratio is 9-80:1.

[0014] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 160-220℃ for 10-40 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0015] The reaction principle of this invention is as follows: In the as-cast Mg-Zn-Y-Nd alloy obtained in step A, the quasicrystalline phase morphology is a euquasic crystal (α-Mg+I-phase) structure with a micron-level interlamellar spacing. After annealing in step B and hot extrusion in step C, the euquasic crystal structure with a micron-level interlamellar spacing is broken into micron-level quasicrystalline (I-Phase) particles. Then, through treatment in step D, the quasicrystalline phase morphology is transformed into a euquasic crystal (α-Mg+I-Phase) structure with a nanometer-level interlamellar spacing. Finally, after a second hot deformation in step E, the euquasic crystal structure with a nanometer-level interlamellar spacing is broken into nanometer-level quasicrystalline (I-Phase) particles, which are dispersed on the α-Mg matrix. In addition, the addition of Nd element can further refine the grain size of the α-Mg matrix and precipitate Mg-Nd nanophase. Thus, a high-performance Mg-Zn-Y alloy with excellent yield strength, tensile strength and elongation is prepared.

[0016] Furthermore, in step A of the present invention, the mass percentage content of each constituent element in the preparation of the as-cast Mg-Zn-Y-Nd alloy is set as follows: 3.8-6.5% Zn, 0.9-1.8% Y, 0.3-0.6% Nd, with the remainder being Mg, and the mass percentage ratio of Zn to Y is 4-5:1.

[0017] Experiments have verified that the mass percentage content of the above-mentioned elements can more stably prepare (α-Mg+I-phase) eutectic reinforced Mg-Zn-Y-Nd alloys with interlamellar spacing of less than 50 nm. Moreover, the low content of alloying elements also reduces the preparation cost of Mg-Zn-Y-Nd alloys. At the same time, when the content of alloying elements is low, the content of (α-Mg+I-phase) eutectic decreases, which enhances the plastic processing performance of Mg-Zn-Y-Nd alloys.

[0018] Furthermore, in step D of the present invention, the Mg-Zn-Y-Nd alloy obtained in step C after hot extrusion is placed in an electromagnetic induction heating furnace, heated to 510-540℃, held for 2-10 minutes, and then subjected to stress quenching treatment.

[0019] Experiments have verified that the above temperature range and holding time are more conducive to the preparation of Mg-Zn-Y-Nd alloys with stable nanoscale interlamellar spacing, which in turn is conducive to the preparation of quasi-crystal-reinforced Mg-Zn-Y-Nd alloys with excellent performance in all aspects and nanoscale quasi-crystal (I-Phase) particles.

[0020] Further, the specific operation of step A in the present invention for preparing the as-cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, pure Mg is placed in a crucible and heated. When heated to 340-360°C, a mixed protective gas of CO2 and SF6 is introduced. After the pure Mg has completely melted, pure Zn, Mg-Y and Mg-Nd intermediate alloys are placed in the pure Mg melt, and the mixture is heated to 720-780°C and stirred for 10-30 minutes. Then, it is refined and allowed to stand for 10-20 minutes. When the temperature drops to 710-740°C, it is poured to obtain the as-cast Mg-Zn-Y-Nd alloy.

[0021] Furthermore, in step C of the present invention, the extrusion ratio for hot extrusion of the annealed Mg-Zn-Y-Nd alloy obtained in step B is 9-30:1.

[0022] Experiments have verified that the above extrusion ratio can make the interlamellae of the subsequently prepared quasi-crystalline reinforced Mg-Zn-Y-Nd alloy more uniform, which is beneficial to the preparation of Mg-Zn-Y-Nd alloy with stable nanoscale interlamellae spacing. This is conducive to the preparation of quasi-crystalline reinforced Mg-Zn-Y-Nd alloy with nanoscale quasi-crystalline (I-Phase) particles with excellent performance in all aspects.

[0023] Furthermore, the quenching medium for stress quenching in step D of the present invention is water at 20-80°C.

[0024] Experiments have verified that stress quenching with water within the above temperature range results in a more uniform interlamellar spacing in the quasicrystalline reinforced Mg-Zn-Y-Nd alloy. This is beneficial for preparing Mg-Zn-Y-Nd alloys with stable nanoscale interlamellar spacing, and thus facilitates the preparation of quasicrystalline reinforced Mg-Zn-Y-Nd alloys with excellent performance in all aspects and nanoscale quasicrystalline (I-Phase) particles.

[0025] Furthermore, the additional stress value for stress quenching treatment in step D of the present invention is 2-50 MPa.

[0026] Experiments have verified that stress quenching with the above-mentioned additional stress can effectively prevent the formation of cracks in the billet caused by rapid cooling, which is beneficial to subsequent secondary hot deformation and greatly improves the product qualification rate. At the same time, it is also beneficial to improve the comprehensive mechanical properties of Mg-Zn-Y-Nd alloy.

[0027] Furthermore, the specific operation of the secondary hot deformation in step E of the present invention is as follows: the secondary hot extrusion deformation temperature is 320-350℃, and the extrusion ratio is 9-30:1.

[0028] Experiments have verified that the Mg-Zn-Y-Nd alloy prepared by the above-mentioned secondary extrusion operation has better comprehensive mechanical properties and can be used to prepare high-performance magnesium alloys with excellent yield strength, tensile strength and elongation.

[0029] Furthermore, the specific operation of the secondary hot deformation in step E of the present invention is as follows: the secondary forging temperature is 320-350℃.

[0030] Experimental results show that the Mg-Zn-Y-Nd alloy prepared by the above-mentioned secondary die forging operation has better comprehensive mechanical properties and can be used to prepare high-performance magnesium alloys with excellent yield strength, tensile strength and elongation.

[0031] Furthermore, in step F of the present invention, the aging temperature is 170-200℃ and the aging time is 10-25h.

[0032] Experiments have verified that aging treatment within the above temperature and time ranges is more effective in precipitating nano-Mg-Nd phases in Mg-Zn-Y-Nd alloys, thereby improving the overall mechanical properties of Mg-Zn-Y-Nd alloys.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] The mass percentage of each component element set in step A ensures that a nanometer-scale (α-Mg+I-phase) eutectic reinforced Mg-Zn-Y-Nd alloy with interlamellar spacing can be obtained through subsequent processing steps B, C, and D. Step B involves annealing at 360-430℃ for 10-20 hours to remove stress from the alloy, giving it better deformability and workability. The billet required for step D can then be obtained through hot extrusion in step C.

[0035] Step D involves semi-solid stress quenching of the quasicrystalline reinforced Mg-Zn-Y-Nd alloy with micron-sized quasicrystalline (I-Phase) particles obtained in Step C. By controlling the temperature, time, stress, and quenching medium temperature of the semi-solid stress quenching treatment, a (α-Mg+I-phase) eutectic reinforced Mg-Zn-Y-Nd alloy with nanoscale interlamellar spacing is obtained in a short time. Then, through secondary extrusion, the quasicrystalline phase is fragmented into nanoscale quasicrystalline (I-Phase) particles, which are dispersed on the α-Mg matrix. Combined with aging treatment, Mg-Nd nanophases are further precipitated, resulting in a quasicrystalline reinforced Mg-Zn-Y-Nd alloy with nanoscale quasicrystalline (I-Phase) particles.

[0036] This invention, based on quasicrystalline reinforced Mg-Zn-Y-Nd alloys with micron-sized quasicrystalline (I-Phase) particles, combines semi-solid stress quenching treatment and secondary hot deformation process to transform the size of the quasicrystalline phase in the alloy from the micron-sized to the nano-sized, thus obtaining a quasicrystalline reinforced Mg-Zn-Y-Nd alloy with nano-sized quasicrystalline (I-Phase) particles. This fully utilizes the reinforcing effect of the quasicrystalline phase, significantly improving the comprehensive mechanical properties of the Mg-Zn-Y-Nd alloy. Furthermore, aging precipitation of Mg-Nd nanophase further enhances the comprehensive mechanical properties. More importantly, this semi-solid stress quenching treatment can avoid cracking of the billet caused by rapid cooling, greatly expanding the industrial application range of Mg-Zn-Y-Nd alloys. Attached Figure Description

[0037] Figure 1 It has a nanoscale quasi-crystalline (α-Mg+I-Phase) structure. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to specific embodiments.

[0039] Example 1

[0040] A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, comprising the following steps:

[0041] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is 3.8% Zn, 0.9% Y, 0.5% Nd, and the remainder is Mg; the specific operation for preparing the cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, place pure Mg in a crucible and heat it. When the temperature reaches 340°C, introduce a CO2 + SF6 mixed protective gas. After the pure Mg has completely melted, place pure Zn, Mg-Y and Mg-Nd intermediate alloys into the pure Mg melt respectively, continue heating to 720°C, stir for 10 minutes, then refine and let stand for 15 minutes. When the temperature drops to 710°C, pour the mixture to obtain the cast Mg-Zn-Y-Nd alloy.

[0042] B. Anneal the as-cast Mg-Zn-Y-Nd alloy prepared in step A at 400℃ for 12 hours, and then cool it in the furnace.

[0043] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 320℃ for 4 hours, it is then hot extruded at an extrusion temperature of 320℃ and an extrusion ratio of 18:1.

[0044] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 540℃, hold it for 5 minutes, and then perform stress quenching treatment with water at 50℃ under an additional stress of 5 MPa.

[0045] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 320℃ for 4 hours, a second hot extrusion is performed. The specific operation of the second hot extrusion is as follows: the second hot extrusion temperature is 320℃ and the extrusion ratio is 9:1.

[0046] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 175℃ for 24 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0047] The Mg-Zn-Y-Nd alloy prepared in this example has a tensile strength of 405 MPa, a yield strength of 340 MPa, and an elongation of 22%.

[0048] Example 2

[0049] A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, comprising the following steps:

[0050] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 5.2% Zn, 1.5% Y, 0.5% Nd, and the remainder is Mg; the specific operation for preparing the cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, place pure Mg in a crucible and heat it. When the temperature reaches 340°C, introduce a CO2 + SF6 mixed protective gas. After the pure Mg has completely melted, place pure Zn, Mg-Y and Mg-Nd intermediate alloys into the pure Mg melt respectively, continue heating to 720°C, stir for 10 minutes, then refine and let stand for 15 minutes. When the temperature drops to 710°C, pour the mixture to obtain the cast Mg-Zn-Y-Nd alloy.

[0051] B. Anneal the as-cast Mg-Zn-Y-Nd alloy prepared in step A at 400℃ for 12 hours, and then cool it in the furnace.

[0052] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 320℃ for 4 hours, it is then hot extruded at an extrusion temperature of 320℃ and an extrusion ratio of 18:1.

[0053] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 540℃, hold it for 5 minutes, and then quench it with water at 50℃ under an additional stress of 5 MPa.

[0054] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 320℃ for 4 hours, a second hot extrusion is performed. The specific operation of the second hot extrusion is as follows: the second hot extrusion temperature is 320℃ and the extrusion ratio is 9:1.

[0055] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 175℃ for 24 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0056] The Mg-Zn-Y alloy prepared in this example has a tensile strength of 418 MPa, a yield strength of 355 MPa, and an elongation of 20%.

[0057] Example 3

[0058] A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, comprising the following steps:

[0059] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 6.5% Zn, 1.8% Y, 0.5% Nd, and the remainder is Mg; the specific operation for preparing the cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, place pure Mg in a crucible and heat it. When the temperature reaches 340°C, introduce a CO2+SF6 mixed protective gas. After the pure Mg has completely melted, place pure Zn, Mg-Y and Mg-Nd intermediate alloys into the pure Mg melt respectively, continue heating to 720°C, stir for 10 minutes, then refine and let stand for 15 minutes. When the temperature drops to 710°C, pour the mixture to obtain the cast Mg-Zn-Y-Nd alloy.

[0060] B. Anneal the as-cast Mg-Zn-Y-Nd alloy prepared in step A at 400℃ for 12 hours, and then cool it in the furnace.

[0061] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 320℃ for 4 hours, it is then hot extruded at an extrusion temperature of 320℃ and an extrusion ratio of 18:1.

[0062] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 540℃, hold it for 5 minutes, and then quench it with water at 50℃ under an additional stress of 5 MPa.

[0063] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 320℃ for 4 hours, a second hot extrusion is performed. The specific operation of the second hot extrusion is as follows: the second hot extrusion temperature is 320℃ and the extrusion ratio is 9:1.

[0064] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 175℃ for 24 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0065] The Mg-Zn-Y alloy prepared in this example has a tensile strength of 426 MPa, a yield strength of 360 MPa, and an elongation of 19%.

[0066] Example 4

[0067] A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, comprising the following steps:

[0068] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 2.5% Zn, 0.5% Y, 1% Nd, and the remainder is Mg; the specific operation for preparing the cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, place pure Mg in a crucible and heat it. When the temperature reaches 340°C, introduce a CO2 + SF6 mixed protective gas. After the pure Mg has completely melted, place pure Zn, Mg-Y and Mg-Nd intermediate alloys into the pure Mg melt respectively, continue heating to 720°C, stir for 10 minutes, then refine and let stand for 15 minutes. When the temperature drops to 710°C, pour the mixture to obtain the cast Mg-Zn-Y-Nd alloy.

[0069] B. Anneal the as-cast Mg-Zn-Y-Nd alloy prepared in step A at 400℃ for 12 hours, and then cool it in the furnace.

[0070] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 320℃ for 4 hours, it is then hot extruded at an extrusion temperature of 320℃ and an extrusion ratio of 18:1.

[0071] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 540℃, hold it for 5 minutes, and then quench it with water at 50℃ under an additional stress of 5 MPa.

[0072] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 320℃ for 4 hours, a second hot extrusion is performed. The specific operation of the second hot extrusion is as follows: the second hot extrusion temperature is 320℃ and the extrusion ratio is 9:1.

[0073] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 175℃ for 24 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0074] The Mg-Zn-Y alloy prepared in this example has a tensile strength of 410 MPa, a yield strength of 345 MPa, and an elongation of 21%.

[0075] Example 5

[0076] A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, comprising the following steps:

[0077] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 11% Zn, 2.5% Y, 0.05% Nd, and the remainder is Mg; the specific operation for preparing the cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, place pure Mg in a crucible and heat it. When the temperature reaches 340°C, introduce a CO2 + SF6 mixed protective gas. After the pure Mg has completely melted, place pure Zn, Mg-Y and Mg-Nd intermediate alloys into the pure Mg melt respectively, continue heating to 720°C, stir for 10 minutes, then refine and let stand for 15 minutes. When the temperature drops to 710°C, pour the mixture to obtain the cast Mg-Zn-Y-Nd alloy.

[0078] B. Anneal the as-cast Mg-Zn-Y-Nd alloy prepared in step A at 400℃ for 12 hours, and then cool it in the furnace.

[0079] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 320℃ for 4 hours, it is then hot extruded at an extrusion temperature of 320℃ and an extrusion ratio of 18:1.

[0080] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 540℃, hold it for 5 minutes, and then quench it with water at 50℃ under an additional stress of 5 MPa.

[0081] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 320℃ for 4 hours, a second hot extrusion is performed. The specific operation of the second hot extrusion is as follows: the second hot extrusion temperature is 320℃ and the extrusion ratio is 9:1.

[0082] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 175℃ for 24 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0083] The Mg-Zn-Y alloy prepared in this example has a tensile strength of 432 MPa, a yield strength of 370 MPa, and an elongation of 18%.

[0084] Example 6

[0085] A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, comprising the following steps:

[0086] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 5.2% Zn, 1.5% Y, 0.5% Nd, and the remainder is Mg; the specific operation for preparing the cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, place pure Mg in a crucible and heat it. When the temperature reaches 340°C, introduce a CO2 + SF6 mixed protective gas. After the pure Mg has completely melted, place pure Zn, Mg-Y and Mg-Nd intermediate alloys into the pure Mg melt respectively, continue heating to 720°C, stir for 10 minutes, then refine and let stand for 15 minutes. When the temperature drops to 710°C, pour the mixture to obtain the cast Mg-Zn-Y-Nd alloy.

[0087] B. Anneal the as-cast Mg-Zn-Y-Nd alloy prepared in step A at 360℃ for 20 hours, and then cool it in the furnace.

[0088] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 300℃ for 4 hours, it is then hot extruded at an extrusion temperature of 300℃ and an extrusion ratio of 9:1.

[0089] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 560°C, and then immediately quench it with water at 80°C under an additional stress of 2 MPa.

[0090] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 300℃ for 4 hours, a second hot extrusion is performed. The specific operation of the second hot extrusion is as follows: the second hot extrusion temperature is 300℃ and the extrusion ratio is 9:1.

[0091] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 160℃ for 40 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0092] The Mg-Zn-Y alloy prepared in this example has a tensile strength of 407 MPa, a yield strength of 336 MPa, and an elongation of 18%.

[0093] Example 7

[0094] A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, comprising the following steps:

[0095] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 5.2% Zn, 1.5% Y, 0.5% Nd, and the remainder is Mg; the specific operation for preparing the cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, place pure Mg in a crucible and heat it. When the temperature reaches 340°C, introduce a CO2 + SF6 mixed protective gas. After the pure Mg has completely melted, place pure Zn, Mg-Y and Mg-Nd intermediate alloys into the pure Mg melt respectively, continue heating to 720°C, stir for 10 minutes, then refine and let stand for 15 minutes. When the temperature drops to 710°C, pour the mixture to obtain the cast Mg-Zn-Y-Nd alloy.

[0096] B. Anneal the as-cast Mg-Zn-Y-Nd alloy prepared in step A at 430℃ for 10 hours, and then cool it in the furnace.

[0097] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 380℃ for 2 hours, it is hot extruded at an extrusion temperature of 380℃ and an extrusion ratio of 80:1.

[0098] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 500℃, hold it for 20 minutes, and then quench it with water at 20℃ under an additional stress of 50 MPa.

[0099] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 380℃ for 2 hours, a second hot extrusion is performed. The specific operation of the second hot extrusion is as follows: the second hot extrusion temperature is 380℃ and the extrusion ratio is 80:1.

[0100] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 220℃ for 10 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0101] The Mg-Zn-Y alloy prepared in this example has a tensile strength of 395 MPa, a yield strength of 328 MPa, and an elongation of 18%.

[0102] Example 8

[0103] A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, comprising the following steps:

[0104] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 5.2% Zn, 1.5% Y, 0.5% Nd, and the remainder is Mg; the specific operation for preparing the cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, place pure Mg in a crucible and heat it. When the temperature reaches 340°C, introduce a CO2 + SF6 mixed protective gas. After the pure Mg has completely melted, place pure Zn, Mg-Y and Mg-Nd intermediate alloys into the pure Mg melt respectively, continue heating to 720°C, stir for 10 minutes, then refine and let stand for 15 minutes. When the temperature drops to 710°C, pour the mixture to obtain the cast Mg-Zn-Y-Nd alloy.

[0105] B. Anneal the as-cast Mg-Zn-Y-Nd alloy prepared in step A at 395℃ for 15 hours, and then cool it in the furnace.

[0106] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 340℃ for 3 hours, it is then hot extruded at an extrusion temperature of 340℃ and an extrusion ratio of 44.5:1.

[0107] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 530℃, hold it for 10 minutes, and then quench it with water at 50℃ under an additional stress of 25 MPa.

[0108] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 340℃ for 3 hours, it is then subjected to a second hot extrusion. The specific operation of the second hot extrusion is as follows: the second hot extrusion temperature is 340℃ and the extrusion ratio is 44.5:1.

[0109] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 190℃ for 25 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0110] The Mg-Zn-Y alloy prepared in this example has a tensile strength of 392 MPa, a yield strength of 325 MPa, and an elongation of 18%.

[0111] Example 9

[0112] A method for preparing nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy by a combination of semi-solid stress quenching and hot deformation, comprising the following steps:

[0113] A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 5.2% Zn, 1.5% Y, 0.5% Nd, and the remainder is Mg; the specific operation for preparing the cast Mg-Zn-Y-Nd alloy is as follows: according to the set mass percentage ratio of each component element, place pure Mg in a crucible and heat it. When the temperature reaches 340°C, introduce a CO2 + SF6 mixed protective gas. After the pure Mg has completely melted, place pure Zn, Mg-Y and Mg-Nd intermediate alloys into the pure Mg melt respectively, continue heating to 720°C, stir for 10 minutes, then refine and let stand for 15 minutes. When the temperature drops to 710°C, pour the mixture to obtain the cast Mg-Zn-Y-Nd alloy.

[0114] B. Anneal the as-cast Mg-Zn-Y-Nd alloy prepared in step A at 400℃ for 12 hours, and then cool it in the furnace.

[0115] C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 320℃ for 4 hours, it is then hot extruded at an extrusion temperature of 320℃ and an extrusion ratio of 18:1.

[0116] D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 540℃, hold it for 5 minutes, and then quench it with water at 50℃ under an additional stress of 5 MPa.

[0117] E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 320℃ for 4 hours, a second forging is performed; the specific operation of the second forging is: the second forging temperature is 320℃.

[0118] F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 175℃ for 24 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

[0119] The Mg-Zn-Y alloy prepared in this example has a tensile strength of 405 MPa, a yield strength of 347 MPa, and an elongation of 21%.

Claims

1. A method for producing a nanocrystalline-quasicrystal reinforced Mg-Zn-Y-Nd alloy by semi-solid stress quenching and hot deformation, characterized in that, The steps are as follows: A. Prepare a cast Mg-Zn-Y-Nd alloy according to the set mass percentage ratio of each component element; the set mass percentage ratio of each component element is: 2.5-11%Zn, 0.5-2.5%Y, 0.05-1%Nd, and the remainder is Mg; B. Anneal the as-cast Mg-Zn-Y alloy prepared in step A at 360-430℃ for 10-20h, and then cool it in the furnace. C. After the annealed Mg-Zn-Y-Nd alloy obtained in step B is held at 300-380℃ for 2-4 hours, it is hot extruded at an extrusion temperature of 300-380℃ and an extrusion ratio of 9-80:

1. D. Place the hot-extruded Mg-Zn-Y-Nd alloy obtained in step C into an electromagnetic induction heating furnace, heat it to 500-560℃, hold it for 0-20 minutes, and then perform stress quenching treatment; the quenching medium for stress quenching treatment is water at 20-80℃, and the additional stress value is 2-50 MPa. E. After holding the Mg-Zn-Y-Nd alloy obtained in step D at 300-380℃ for 2-4 hours, a second hot deformation is performed. The specific operation of the second hot deformation is as follows: the second hot deformation temperature is 300-380℃ and the extrusion ratio is 9-80:

1. F. The Mg-Zn-Y-Nd alloy obtained in step E is aged at 160-220℃ for 10-40 hours to obtain a nano-quasi-crystalline reinforced Mg-Zn-Y-Nd alloy.

2. The method for preparing nanocrystalline reinforced Mg-Zn-Y-Nd alloy by semi-solid stress quenching and hot deformation according to claim 1, characterized in that: The mass percentages of each constituent element in step A of the preparation of the as-cast Mg-Zn-Y-Nd alloy are set as follows: 3.8-6.5% Zn, 0.9-1.8% Y, 0.3-0.6% Nd, with the remainder being Mg, and the mass percentage ratio of Zn to Y is 4-5:

1.

3. The method for preparing nanocrystalline reinforced Mg-Zn-Y-Nd alloy by semi-solid stress quenching and hot deformation according to claim 2, characterized in that: In step D, the Mg-Zn-Y-Nd alloy obtained in step C after hot extrusion is placed in an electromagnetic induction heating furnace, heated to 510-540℃, held for 2-10 minutes, and then subjected to stress quenching treatment.

4. The method for preparing nanocrystalline-quasicrystal reinforced Mg-Zn-Y-Nd alloy by semi-solid stress quenching and hot deformation according to any one of claims 1-3, characterized in that: The specific operation for preparing the as-cast Mg-Zn-Y-Nd alloy in step A is as follows: According to the set mass percentage ratio of each component element, pure Mg is placed in a crucible and heated. When heated to 340-360℃, a mixed protective gas of CO2 + SF6 is introduced. After the pure Mg has completely melted, pure Zn, Mg-Y and Mg-Nd intermediate alloys are placed in the pure Mg melt, and the mixture is heated to 720-780℃ and stirred for 10-30 minutes. Then, it is refined and allowed to stand for 10-20 minutes. When the temperature drops to 710-740℃, it is poured to obtain the as-cast Mg-Zn-Y-Nd alloy.

5. The method for preparing nanocrystalline reinforced Mg-Zn-Y-Nd alloy by semi-solid stress quenching and hot deformation according to claim 1, characterized in that: In step C, the hot extrusion ratio of the annealed Mg-Zn-Y-Nd alloy obtained in step B is 9-30:

1.

6. The method for preparing nanocrystalline reinforced Mg-Zn-Y-Nd alloy by semi-solid stress quenching and hot deformation according to claim 1, characterized in that: The specific operation of the secondary hot deformation in step E is as follows: the secondary hot extrusion deformation temperature is 320-350℃, and the extrusion ratio is 9-30:

1.

7. The method for preparing nanocrystalline reinforced Mg-Zn-Y-Nd alloy by semi-solid stress quenching and hot deformation according to claim 1, characterized in that: The specific operation of the secondary hot deformation in step E is as follows: the secondary forging temperature is 320-350℃.

8. The method for preparing nanocrystalline reinforced Mg-Zn-Y-Nd alloy by semi-solid stress quenching and hot deformation according to claim 1, characterized in that: The aging temperature in step F is 170-200 °C, and the aging time is 10-25 h.

Images