Preparation method of double-phase magnesium-lithium alloy and rolling heat treatment process of double-phase magnesium-lithium alloy
By adding carboxylated graphene to support titanium powder to generate a TiC reinforcing phase and optimizing the rolling and heat treatment processes, the problems of poor plasticity and insufficient strength of magnesium-lithium alloys were solved, achieving a balance between high strength and high elongation of the material.
Patent Information
- Application Number
- CN202510915199.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-03
- Publication Date
- 2025-11-04
AI Technical Summary
The close-packed hexagonal crystal structure of traditional magnesium alloys limits their room temperature plastic deformation capacity, resulting in low processing efficiency, poor adaptability to rolling processes, and insufficient heat treatment efficiency. This affects the balance of mechanical properties, making it difficult to simultaneously improve the contradiction between elongation and strength.
Carboxylated graphene-supported titanium powder was blended and smelted with magnesium-lithium alloy to generate a TiC reinforcing phase. Combined with optimized rolling and heat treatment processes, the distribution and grain size of the α/β phases were controlled. Through multi-pass rolling and annealing, the ratio of the α/β magnesium-lithium dual phases was adjusted to improve the strength and plasticity of the material.
It significantly improves the yield strength, tensile strength and elongation of magnesium-lithium alloys, solves the problems of uneven α/β phase distribution and grain coarsening in magnesium-lithium alloys during rolling, and achieves a balance between strength and elongation.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of magnesium-lithium alloy technology, specifically to a method for preparing a dual-phase magnesium-lithium alloy and its rolling heat treatment process. Background Technology
[0002] Magnesium alloys are considered ideal lightweight materials due to their low density, high specific strength / stiffness, and excellent electromagnetic shielding, thermal conductivity, and damping properties, and are widely used in aerospace, automotive, and 3C fields. However, the close-packed hexagonal crystal structure of traditional magnesium alloys limits their room-temperature plastic deformation capabilities, with only basal slip systems activated and an insufficient number of independent slip systems, resulting in a tendency for brittle fracture and low processing efficiency.
[0003] To address the aforementioned issues, existing technologies induce a transformation of the magnesium matrix from an HCP structure to a body-centered cubic structure by adding lithium, increasing the number of slip systems and thus significantly improving plasticity. However, existing processes suffer from the following problems: poor adaptability of rolling processes, as traditional rolling parameters are not optimized for the phase transformation characteristics of dual-phase magnesium-lithium alloys, easily leading to uneven α / β phase distribution and affecting the balance of mechanical properties; insufficient heat treatment efficiency, as the annealing and homogenization processes are not precisely matched to changes in lithium content, resulting in grain coarsening or β-Li phase aggregation, reducing the material's corrosion resistance; and a contradiction between elongation and strength, as existing processes struggle to simultaneously improve elongation.
[0004] Graphene is one of the strongest known materials with an extremely high modulus. When uniformly dispersed in an alloy matrix, it effectively hinders dislocation movement, bears and transfers loads, and acts as a heterogeneous nucleation site, promoting grain refinement during alloy solidification and enhancing material strength. It significantly improves the strength, hardness, and elastic modulus of the alloy, achieving remarkable reinforcement even at very low concentrations, with efficiency far exceeding that of traditional reinforcements. It is frequently added to alloy materials to improve their properties. TiC is a common and readily available additive that can effectively enhance material strength. Rolling technology is also a crucial factor affecting alloy strength, but current research has not effectively utilized the synergistic effect of combining TiC's properties with the rolling process to improve the strength of magnesium-lithium alloys. Summary of the Invention
[0005] (a) Technical problems to be solved:
[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing a dual-phase magnesium-lithium alloy and its rolling heat treatment process, which solves the problems of insufficient yield strength, tensile strength, and elongation of traditional dual-phase magnesium-lithium alloys.
[0007] (II) Technical Solution: The preparation method of dual-phase magnesium-lithium alloy includes:
[0008] (1) Add carboxylated graphene and titanium powder to water, disperse by ultrasonication and stir, then filter and dry to obtain graphene-supported titanium.
[0009] (2) Elemental magnesium, graphene-supported titanium and elemental zinc are placed in a planetary ball mill and mixed in an argon atmosphere. The mixture is then placed in a melting furnace, covered with flux, and argon is introduced for a first melting. Elemental lithium is then added for a second melting. After melting, the mixture is cast into a mold and cooled to form a dual-phase magnesium-lithium alloy.
[0010] Furthermore, in (1), the ultrasonic time is 20-40 min and the stirring time is 2-3 h.
[0011] Furthermore, in (1), the mass ratio of carboxylated graphene to titanium powder is 100:(5-20).
[0012] Furthermore, in (2), the ball milling speed is 300-600 r / min and the ball milling time is 2-3 h.
[0013] Furthermore, in (2), the mass ratio of elemental magnesium, graphene-supported titanium, elemental zinc, and elemental lithium is (87.7-93):(0.4-1.2):(0.5-1.1):(5.5-10.6).
[0014] Furthermore, in (2), the temperature of the first melting is 720-750℃; the temperature of the second melting is 670-690℃.
[0015] Furthermore, in (2), the flux is lithium fluoride and lithium chloride in a mass ratio of 1:(2.8-3.3).
[0016] Furthermore, the rolling heat treatment process for the dual-phase magnesium-lithium alloy is as follows: the dual-phase magnesium-lithium alloy is rolled in a twin-roll mill in multiple passes, with the homogenization temperature controlled at 280-300℃ and the time at 18-30h to eliminate compositional segregation; the annealing temperature is controlled at 150-280℃ to promote dynamic recrystallization and uniform distribution of the β-Li phase; the hot working temperature is controlled at 180-320℃, the roll preheating temperature is controlled at 170-350℃, and the reduction in each rolling pass is controlled at 30-90%, with the reduction in the first pass being 40-80%, to obtain the rolled dual-phase magnesium-lithium alloy material.
[0017] (III) Beneficial technical effects: The carboxylated graphene of the present invention contains a large number of carboxyl groups, which form coordination interactions with the surface of titanium powder, so that the titanium powder is uniformly loaded onto the graphene surface to obtain graphene-loaded titanium. Then, it is blended and smelted with magnesium, lithium, etc. During the ball milling process, the graphene and titanium are not easily separated through coordination. Thus, during the high-temperature smelting process, titanium generates TiC ceramic phase in situ on the graphene surface, which combines with graphene to form a reinforcing phase, significantly improving the mechanical properties of magnesium-lithium alloy, exhibiting higher yield strength, tensile strength, elongation, etc.
[0018] In the magnesium-lithium alloy rolling production process described in this invention, by optimizing the homogenization temperature, compositional segregation is eliminated; by controlling the annealing temperature, dynamic recrystallization and uniform distribution of the β-Li phase are promoted; by controlling the hot working temperature, roll preheating temperature, and the reduction amount in each rolling pass, stress concentration is avoided, effectively improving the elongation of the magnesium-lithium alloy; and by adjusting the α / β magnesium-lithium dual-phase ratio to regulate mechanical properties, the rolling deformation strengthening has universality. This solves the problems of poor room-temperature plasticity and insufficient processing performance caused by the HCP structure of magnesium alloys, uneven α / β phase distribution, and grain coarsening during the rolling process of dual-phase magnesium-lithium alloys; and achieves a balance between elongation and strength. Detailed Implementation
[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] The graphene product number 135644 and the carboxylated graphene product number 115035 mentioned below are both from Shanghai Ziyi Reagent Factory.
[0021] Example 1:
[0022] (1) Add 10g of carboxylated graphene and 2g of titanium powder to 5L of water, ultrasonically disperse for 20min, stir for 2h, filter and dry to obtain graphene-supported titanium.
[0023] (2) 9.3 kg of elemental magnesium, 40 g of graphene-supported titanium and 110 g of elemental zinc were placed in a planetary ball mill and ball milled at 300 r / min for 3 h in an argon atmosphere. The mixture was then placed in a melting furnace and covered with flux, which consisted of lithium fluoride and lithium chloride in a mass ratio of 1:2.8. The mixture was melted at 720 °C in an argon atmosphere. Then 550 g of elemental lithium was added and the mixture was melted at 690 °C. After melting, the mixture was cast into a mold and cooled to form a dual-phase magnesium-lithium alloy.
[0024] (3) The dual-phase magnesium-lithium alloy is rolled in a twin-roll mill in multiple passes, with the homogenization temperature controlled at 280°C and the time at 30h; the annealing temperature controlled at 150°C; the hot working temperature controlled at 180°C; the roll preheating temperature controlled at 350°C; and the reduction of each rolling pass controlled at 90%, with the reduction of the first pass being 40%, to obtain the dual-phase magnesium-lithium alloy rolled material.
[0025] Example 2:
[0026] (1) Add 10g of carboxylated graphene and 0.5g of titanium powder to 3L of water, ultrasonically disperse for 40min, stir for 3h, filter and dry to obtain graphene-supported titanium.
[0027] (2) 8.97 kg of elemental magnesium, 80 g of graphene-supported titanium and 70 g of elemental zinc were placed in a planetary ball mill and ball milled at 480 r / min for 2 h in an argon atmosphere. The mixture was then placed in a melting furnace and covered with flux, which consisted of lithium fluoride and lithium chloride in a mass ratio of 1:3. The mixture was then melted at 735 °C in an argon atmosphere. Then 880 g of elemental lithium was added and the mixture was melted at 685 °C. After melting, the mixture was cast into a mold and cooled to form a dual-phase magnesium-lithium alloy.
[0028] (3) The dual-phase magnesium-lithium alloy is rolled in a twin-roll mill in multiple passes, with the homogenization temperature controlled at 290°C and the time at 24h; the annealing temperature controlled at 180°C; the hot working temperature controlled at 260°C; the roll preheating temperature controlled at 240°C; and the reduction of each rolling pass controlled at 70%, with the reduction of the first pass being 50%, to obtain the dual-phase magnesium-lithium alloy rolled material.
[0029] Example 3:
[0030] (1) Add 10g of carboxylated graphene and 1.25g of titanium powder to 5L of water, ultrasonically disperse for 30min, stir for 3h, filter and dry to obtain graphene-supported titanium.
[0031] (2) 9.14 kg of elemental magnesium, 110 g of graphene-supported titanium and 70 g of elemental zinc were placed in a planetary ball mill and ball-milled at 300 r / min for 3 h in an argon atmosphere. The mixture was then placed in a melting furnace and covered with flux, which consisted of lithium fluoride and lithium chloride in a mass ratio of 1:3.2. The mixture was then melted at 720 °C in an argon atmosphere. Then 680 g of elemental lithium was added and the mixture was melted at 670 °C. After melting, the mixture was cast into a mold and cooled to form a dual-phase magnesium-lithium alloy.
[0032] (3) The dual-phase magnesium-lithium alloy is rolled in a twin-roll mill in multiple passes, with the homogenization temperature controlled at 295°C and the time at 25h; the annealing temperature controlled at 230°C; the hot working temperature controlled at 260°C; the roll preheating temperature controlled at 280°C; and the reduction of each rolling pass controlled at 60%, with the reduction of the first pass being 80%, to obtain the dual-phase magnesium-lithium alloy rolled material.
[0033] Example 4:
[0034] (1) Add 10g of carboxylated graphene and 0.85g of titanium powder to 3L of water, disperse ultrasonically for 35min, stir for 2h, filter and dry to obtain graphene-supported titanium.
[0035] (2) 8.77 kg of elemental magnesium, 120 g of graphene-supported titanium and 50 g of elemental zinc were placed in a planetary ball mill and ball-milled at 600 r / min for 2 h in an argon atmosphere. The mixture was then placed in a melting furnace and covered with flux, which consisted of lithium fluoride and lithium chloride in a mass ratio of 1:3.3. The mixture was melted at 750 °C in an argon atmosphere. Then 1060 g of elemental lithium was added and the mixture was melted at 690 °C. After melting, the mixture was cast into a mold and cooled to form a dual-phase magnesium-lithium alloy.
[0036] (3) The dual-phase magnesium-lithium alloy is rolled in a twin-roll mill in multiple passes, with the homogenization temperature controlled at 300℃ and the time at 18h; the annealing temperature controlled at 280℃; the hot working temperature controlled at 320℃; the roll preheating temperature controlled at 170℃; and the reduction of each rolling pass controlled at 30%, with the reduction of the first pass being 40%, to obtain the dual-phase magnesium-lithium alloy rolled material.
[0037] Comparative Example 1:
[0038] (1) 9.3 kg of elemental magnesium and 110 g of elemental zinc were placed in a planetary ball mill and ball-milled at 300 r / min for 3 h in an argon atmosphere. The mixture was then placed in a melting furnace and covered with flux, which consisted of lithium fluoride and lithium chloride in a mass ratio of 1:2.8. The mixture was then melted at 720 °C in an argon atmosphere. Then, 550 g of elemental lithium was added and the mixture was melted at 690 °C. After melting, the mixture was cast into a mold and cooled to form a dual-phase magnesium-lithium alloy.
[0039] (2) The dual-phase magnesium-lithium alloy was rolled in a twin-roll mill in multiple passes, with the homogenization temperature controlled at 280°C and the time at 30h; the annealing temperature controlled at 150°C; the hot working temperature controlled at 180°C; the roll preheating temperature controlled at 350°C; and the reduction of each rolling pass controlled at 90%, with the reduction of the first pass being 40%, to obtain the dual-phase magnesium-lithium alloy rolled material.
[0040] Comparative Example 2:
[0041] (1) 9.3 kg of elemental magnesium, 40 g of carboxylated graphene and 110 g of elemental zinc were placed in a planetary ball mill and ball milled at 300 r / min for 3 h in an argon atmosphere. The mixture was then placed in a melting furnace and covered with flux, which consisted of lithium fluoride and lithium chloride in a mass ratio of 1:2.8. The mixture was then smelted at 720 °C in an argon atmosphere. Then 550 g of elemental lithium was added and the mixture was smelted at 690 °C. After melting, the mixture was cast into a mold and cooled to form a dual-phase magnesium-lithium alloy.
[0042] (2) The dual-phase magnesium-lithium alloy was rolled in a twin-roll mill in multiple passes, with the homogenization temperature controlled at 280°C and the time at 30h; the annealing temperature controlled at 150°C; the hot working temperature controlled at 180°C; the roll preheating temperature controlled at 350°C; and the reduction of each rolling pass controlled at 90%, with the reduction of the first pass being 40%, to obtain the dual-phase magnesium-lithium alloy rolled material.
[0043] Comparative Example 3:
[0044] (1) Add 10g of graphene and 2g of titanium powder to 5L of water, ultrasonically disperse for 20min, stir for 2h, filter and dry to obtain graphene-supported titanium.
[0045] (2) 9.3 kg of elemental magnesium, 40 g of graphene-supported titanium and 110 g of elemental zinc were placed in a planetary ball mill and ball milled at 300 r / min for 3 h in an argon atmosphere. The mixture was then placed in a melting furnace and covered with flux, which consisted of lithium fluoride and lithium chloride in a mass ratio of 1:2.8. The mixture was then smelted at 720 °C in an argon atmosphere. Then 550 g of elemental lithium was added and the mixture was smelted at 690 °C. After melting, the mixture was cast into a mold and cooled to form a dual-phase magnesium-lithium alloy.
[0046] (3) The dual-phase magnesium-lithium alloy is rolled in a twin-roll mill in multiple passes, with the homogenization temperature controlled at 280°C and the time at 30h; the annealing temperature controlled at 150°C; the hot working temperature controlled at 180°C; the roll preheating temperature controlled at 350°C; and the reduction of each rolling pass controlled at 90%, with the reduction of the first pass being 40%, to obtain the dual-phase magnesium-lithium alloy rolled material.
[0047] Referring to GB / T 228.1-2021 standard, the yield strength, tensile strength and elongation of duplex magnesium-lithium alloy rolled materials were tested using an electronic universal tensile testing machine, with the tensile speed set at 2 mm / min.
[0048] Table 1 Properties of magnesium-lithium alloys
[0049]
[0050] In Examples 1-4, graphene-supported titanium, formed by combining carboxyl graphene and titanium powder, was added. This titanium was not easily separated from the raw materials during ball milling and readily formed a TiC reinforcing phase at high temperatures, improving the yield strength, tensile strength, and elongation of the magnesium-lithium alloy. In Comparative Example 1, no graphene-supported titanium was added, resulting in a magnesium-lithium alloy with insufficient strength, making large-scale application difficult. Comparative Example 2, which only added carboxyl graphene, showed a weaker reinforcing effect compared to the reinforcing phase formed by combining it with titanium powder, and its ability to improve the performance of the magnesium-lithium alloy was insufficient. Comparative Example 3 added graphene-supported titanium, formed by combining ordinary graphene and titanium powder. However, due to the lower carboxyl groups on ordinary graphene, the bonding ability with titanium powder was poor, leading to easy separation during ball milling. Therefore, less TiC reinforcing phase was formed, resulting in a decreased reinforcing effect on the magnesium-lithium alloy.
[0051] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. 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 be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.
Claims
1. A method for preparing a dual-phase magnesium-lithium alloy, characterized in that, The preparation method includes: (1) Add carboxylated graphene and titanium powder to water, disperse by ultrasonication and stir, then filter and dry to obtain graphene-supported titanium. (2) Elemental magnesium, graphene-supported titanium and elemental zinc are placed in a planetary ball mill and mixed in an argon atmosphere. The mixture is then placed in a melting furnace, covered with flux, and argon is introduced for a first melting. Elemental lithium is then added for a second melting. After melting, the mixture is cast into a mold and cooled to form a dual-phase magnesium-lithium alloy.
2. The method for preparing the dual-phase magnesium-lithium alloy according to claim 1, characterized in that, The ultrasonic time in (1) is 20-40 min, and the stirring time is 2-3 h.
3. The method for preparing the dual-phase magnesium-lithium alloy according to claim 1, characterized in that, The mass ratio of carboxylated graphene to titanium powder in (1) is 100:(5-20).
4. The method for preparing the dual-phase magnesium-lithium alloy according to claim 1, characterized in that, In (2), the ball milling speed is 300-600 r / min and the ball milling time is 2-3 h.
5. The method for preparing the dual-phase magnesium-lithium alloy according to claim 1, characterized in that, In (2), the mass ratio of elemental magnesium, graphene-supported titanium, elemental zinc, and elemental lithium is (87.7-93):(0.4-1.2):(0.5-1.1):(5.5-10.6).
6. The method for preparing the dual-phase magnesium-lithium alloy according to claim 1, characterized in that, The temperature of the first melting in (2) is 720-750℃; the temperature of the second melting is 670-690℃.
7. The method for preparing the dual-phase magnesium-lithium alloy according to claim 1, characterized in that, The flux in (2) is lithium fluoride and lithium chloride in a mass ratio of 1:(2.8-3.3).
8. A rolling heat treatment process for a dual-phase magnesium-lithium alloy obtained by the preparation method according to any one of claims 1-7, characterized in that, The rolling heat treatment process is as follows: the dual-phase magnesium-lithium alloy is rolled in a twin-roll mill in multiple passes, with the homogenization temperature controlled at 280-300℃ and the time at 18-30h; the annealing temperature controlled at 150-280℃; the hot working temperature controlled at 180-320℃; the roll preheating temperature controlled at 170-350℃; and the reduction in each rolling pass controlled at 30-90%, with the reduction in the first pass being 40-80%, to obtain the dual-phase magnesium-lithium alloy rolled material.