CN114540686A - Multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy and preparation method thereof - Google Patents
Multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy and preparation method thereof Download PDFInfo
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- 239000001989 lithium alloy Substances 0.000 title claims abstract description 116
- GCICAPWZNUIIDV-UHFFFAOYSA-N lithium magnesium Chemical compound [Li].[Mg] GCICAPWZNUIIDV-UHFFFAOYSA-N 0.000 title claims abstract description 111
- 229910000733 Li alloy Inorganic materials 0.000 title claims abstract description 110
- 238000002360 preparation method Methods 0.000 title abstract description 20
- 239000000956 alloy Substances 0.000 claims abstract description 107
- 239000002994 raw material Substances 0.000 claims abstract description 97
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 39
- 238000000034 method Methods 0.000 claims abstract description 37
- 229910052777 Praseodymium Inorganic materials 0.000 claims abstract description 33
- 229910052688 Gadolinium Inorganic materials 0.000 claims abstract description 28
- 230000008569 process Effects 0.000 claims abstract description 26
- 229910052779 Neodymium Inorganic materials 0.000 claims abstract description 23
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 23
- 239000012535 impurity Substances 0.000 claims abstract description 22
- 229910052718 tin Inorganic materials 0.000 claims abstract description 16
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 13
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 9
- 229910045601 alloy Inorganic materials 0.000 claims description 101
- 238000010438 heat treatment Methods 0.000 claims description 74
- 238000009750 centrifugal casting Methods 0.000 claims description 38
- 239000006104 solid solution Substances 0.000 claims description 33
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 32
- 230000032683 aging Effects 0.000 claims description 27
- 239000007789 gas Substances 0.000 claims description 24
- 229910052751 metal Inorganic materials 0.000 claims description 19
- 239000002184 metal Substances 0.000 claims description 19
- 229910019400 Mg—Li Inorganic materials 0.000 claims description 18
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 16
- 229910052786 argon Inorganic materials 0.000 claims description 16
- 229910052802 copper Inorganic materials 0.000 claims description 16
- 239000010949 copper Substances 0.000 claims description 16
- 230000001681 protective effect Effects 0.000 claims description 16
- 238000003723 Smelting Methods 0.000 claims description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 12
- 238000000227 grinding Methods 0.000 claims description 12
- 229910017073 AlLi Inorganic materials 0.000 claims description 10
- AHLBNYSZXLDEJQ-FWEHEUNISA-N orlistat Chemical compound CCCCCCCCCCC[C@H](OC(=O)[C@H](CC(C)C)NC=O)C[C@@H]1OC(=O)[C@H]1CCCCCC AHLBNYSZXLDEJQ-FWEHEUNISA-N 0.000 claims description 10
- 238000002844 melting Methods 0.000 claims description 9
- 230000008018 melting Effects 0.000 claims description 9
- 238000004321 preservation Methods 0.000 claims description 9
- 229910017706 MgZn Inorganic materials 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 8
- 230000008859 change Effects 0.000 claims description 8
- 238000011049 filling Methods 0.000 claims description 8
- 239000011888 foil Substances 0.000 claims description 8
- 239000002932 luster Substances 0.000 claims description 8
- 238000012544 monitoring process Methods 0.000 claims description 8
- 230000003647 oxidation Effects 0.000 claims description 8
- 238000007254 oxidation reaction Methods 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 229910002804 graphite Inorganic materials 0.000 claims description 2
- 239000010439 graphite Substances 0.000 claims description 2
- 239000010935 stainless steel Substances 0.000 claims description 2
- 229910001220 stainless steel Inorganic materials 0.000 claims description 2
- 239000012467 final product Substances 0.000 claims 1
- 239000011777 magnesium Substances 0.000 abstract description 48
- 229910000861 Mg alloy Inorganic materials 0.000 abstract description 6
- 238000005728 strengthening Methods 0.000 description 23
- 238000005275 alloying Methods 0.000 description 13
- 239000011159 matrix material Substances 0.000 description 9
- 238000005303 weighing Methods 0.000 description 7
- 239000013078 crystal Substances 0.000 description 6
- 229910052761 rare earth metal Inorganic materials 0.000 description 6
- 239000006185 dispersion Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000001125 extrusion Methods 0.000 description 4
- 238000005498 polishing Methods 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 229910017708 MgZn2 Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000013079 quasicrystal Substances 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C23/00—Alloys based on magnesium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D13/00—Centrifugal casting; Casting by using centrifugal force
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/02—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working in inert or controlled atmosphere or vacuum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon
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Abstract
The invention discloses a multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy and a preparation method thereof, wherein the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following elements in percentage by mass: al: 1-5wt.%, Gd: 0.1-2wt.%, Y: 0.5-3wt.%, Li: 5-12wt.%, Zn: 0.2-3wt.%, Mn: 0.1-0.8wt.%, Sn: 0.1-1.5wt.%, Pr: 0.1-1.5wt.%, Nd: 0.1-1.5wt.%, the balance Mg and impurities; the content of the impurities
0.03 wt%. The method has the advantages of low price, high efficiency, advanced and simple process, high raw material yield, wide application range and the like, can ensure the low density and light weight of the magnesium-lithium alloy, and simultaneously obviously improves the mechanical properties of the multielement microalloying biphase magnesium-lithium alloy, such as strength, elongation, elastic modulus, plasticity and the like. The invention is suitable for the field of magnesium alloy materials.
Description
Technical Field
The invention belongs to the field of magnesium alloy materials, and particularly relates to a multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy and a preparation method thereof.
Background
With the increasing requirements for light weight and environmental protection of weaponry, alloy materials with ultra-high strength are receiving attention. Among them, the Mg-Li alloy is the lightest of the structural materials and has the density of 1.25-1.65g/cm3) Only half of the aluminum alloy material. Compared with other metal materials, the Mg-Li alloy has high specific strength and specific stiffness, good damping property, machinability and electromagnetic shielding property, has huge market application prospect in the high and new technical fields of aerospace, 3C industry, military, communication and the like, and particularly, the Mg-Li alloy can rise rapidly under the conditions that the current natural resources are increasingly deficient and the magnesium resource reserves are rich.
At present, many research reports on magnesium-lithium alloys are reported, specifically as follows:
chinese patent CN 107541626A discloses a multi-element microalloy grain refinement type magnesium-lithium alloy and a preparation method thereof, wherein a small amount of composite blocks are added into LA141 magnesium-lithium alloy, so that the material is subjected to multi-element microalloying, although the magnesium-lithium alloy can be microalloyed, the addition of the composite blocks can cause brittle fracture of the alloy, and the alloy is not suitable for engineering application with high requirement on plasticity because the interface bonding strength of the alloy and a magnesium-lithium alloy matrix is not high.
Chinese patent CN 112746210B discloses a multi-element microalloyed magnesium alloy, a preparation method thereof and a plate extrusion molding process, wherein alloying is carried out by adding alloy elements and the mechanical property of Mg-6Zn-1Gd-0.12Y-0.21Nd-0.03Ca alloy is improved by the extrusion process, but the synergistic improvement of alloy strength, elastic modulus and density is not considered, the density of the magnesium alloy is obviously improved and a second phase with low modulus is formed by adding a large amount of Zn, so that the magnesium alloy is not beneficial to industrial lightweight application and material application of high-modulus structural members, and the use working conditions of actual complex industrial structural members cannot be met.
Chinese patent CN 110029254B discloses a multi-element microalloyed two-phase magnesium-lithium alloy and a preparation method thereof, the strength of the alloy is improved by the methods of microalloying, extrusion forming and the like of various alloy elements, and the complex working condition that the strength of the magnesium-lithium alloy is 220-plus-250 MPa, is lower than 300MPa, the yield strength is 140-plus-190 MPa, is lower than 200MPa and still cannot meet the industrial application is obtained. Meanwhile, the preparation method is complex, complicated hot processing needs to be carried out on the cast ingot, and the plate obtained by extrusion deformation and hot rolling is simple in structure and is not suitable for application requiring high-strength high-modulus low-density materials.
Aiming at the defects of low strength, low elastic modulus, large preparation difficulty and the like of the existing Mg-Li alloy, how to improve the mechanical properties of the Mg-Li alloy such as strength, modulus and the like is particularly important.
Disclosure of Invention
In order to solve the defects and shortcomings, the invention provides a multi-microalloyed high-strength high-modulus biphase magnesium-lithium alloy and a preparation method thereof, wherein the mechanical properties of the magnesium-lithium alloy are improved by regulating and controlling the Li element content and proportion in the magnesium-lithium alloy, multi-alloying, vacuum centrifugal smelting, heat treatment and other processes and utilizing strengthening mechanisms such as solid solution strengthening, aging strengthening, dispersion strengthening, fine grain strengthening and the like, so that the multi-alloying high-strength high-modulus biphase magnesium-lithium alloy with the requirements of low density, high strength, high elongation and high modulus is prepared, and the large-scale application of Mg-Li alloy materials in the fields of aerospace, precision instruments, missiles and the like is met.
In order to achieve the above object, the first aspect of the present invention provides the following solutions:
a multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following elements in percentage by mass: al: 1-5wt.%, Gd: 0.1-2wt.%, Y: 0.5-3wt.%, Li: 5-12wt.%, Zn: 0.2-3wt.%, Mn: 0.1-0.8wt.%, Sn: 0.1-1.5wt.%, Pr: 0.1-1.5wt.%, Nd: 0.1-1.5wt.%, the balance Mg and impurities;
the content of the impurities
0.03wt%。
As an embodiment of the invention, the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy mainly has a structure
-Mg，
-Li，Al2RE(Nd，Gd，Y，Pr)，Mg3(Nd, Pr, Sn)，Al8Mn5，AlLi，Mg24Y5，MgZn(Gd，Y)，Li17Sn4，MgLi2Al and MgLi2Zn；
Wherein,
-Mg in a proportion of 30-80%,
-a Li proportion of 30-70%,
phase C
The total proportion of phases does not exceed 95%.
As an embodiment of the invention, the properties of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy are as follows: the density is 1.3-1.9g/cm3The tensile strength is 280-430MPa, the yield strength is 240-360MPa, the elongation is 15-35 percent, and the elastic modulus is 60-75 GPa.
A method for preparing the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy of the first aspect of the invention, which comprises the following steps:
s1: raw material selection
According to the composition and the mass percentage of each element in the multi-element microalloyed high-strength high-modulus biphase magnesium-lithium alloy, pure Mg, pure Al, pure Zn, pure Sn, Mg-Li intermediate alloy, Mg-Gd intermediate alloy, Mg-Y intermediate alloy, Mg-Mn intermediate alloy, Mg-Pr intermediate alloy and Mg-Nd intermediate alloy are used as raw materials for weighing, and a grinding machine is used for grinding surface oxides to keep the metal luster for the later use;
s2: stage of preheating raw materials
Wrapping the raw materials weighed in the step S1 with aluminum foil, putting the raw materials, the crucible and the metal copper mold into a heat treatment furnace for preheating, and reserving for later use;
s3: charging phase
Firstly, placing the preheated crucible and the metal copper mold in the step S2 into a vacuum centrifugal casting furnace with argon protection, then placing the preheated raw materials into different positions of the crucible in the centrifugal casting furnace, then opening a cold water circulator and covering a furnace cover, and starting to vacuumize the atmosphere in the furnace to 10 DEG C-3Below Pa, then filling protective gas argon into the furnace;
s4: vacuum centrifugal smelting stage
After the step S3, adjusting the heating current and power of the centrifugal casting furnace, starting to heat and melt the raw material, firstly heating at low power until the crucible is red hot, then heating at high power until the raw material is melted, starting to preserve heat, then setting the centrifugal casting speed and starting to cast to obtain a magnesium-lithium alloy ingot, and monitoring the temperature change in the furnace by an infrared thermometer in the whole process;
s5: stage of heat treatment
Putting the magnesium-lithium alloy cast ingot obtained in the step S4 into a vacuum tube furnace, and vacuumizing the furnace atmosphere to 10 DEG-3Introducing protective gas into the furnace until the gas pressure reaches the atmospheric pressure; setting heat treatment temperature, and then carrying out solid solution aging heat treatment process to finally obtain the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy.
In step S1, the mass purities of pure Mg, pure Al, pure Sn, and pure Zn are all 99.90-99.999%;
in step S1, the raw materials include Li, Gd, Y, Mn, Pr and Nd in the mass content of 10-50wt.% in the Mg-Li intermediate alloy, the Mg-Gd intermediate alloy, the Mg-Y intermediate alloy, the Mg-Mn intermediate alloy, the Mg-Pr intermediate alloy and the Mg-Nd intermediate alloy.
In step S2, the preheating temperature is 80-250 ℃ and the preheating time is 0.5-2 h;
in step S2, the crucible is: graphite crucibles, BN crucibles or stainless steel crucibles.
As an embodiment of the present invention, in step S3, the crucible in the centrifugal casting furnace is placed at different positions according to the melting point, the degree of easy oxidation, the density, the amount of addition, the degree of easy volatilization, and other factors of the raw material; in consideration of the fact that Li is active and flammable and the upper temperature is relatively low in the crucible heating process, small pure Mg blocks are placed at the bottom, then Mg-Gd, Mg-Y, Mg-Mn, Mg-Pr and Mg-Nd intermediate alloys are placed, pure Zn and pure Al are placed, and finally the Mg-Li intermediate alloy is placed.
As an embodiment of the present invention, the vacuum centrifugal melting stage in step S4 includes:
s401: the heating current is 1.0-5.0A, and the heating power is 50-100%;
s402: the raw materials are heated and melted by adopting a gradient heating mode, the raw materials are firstly heated to be red hot in a crucible at low power, and the power is as follows: 50% -70%; heating to melt by adopting high power, wherein the high power is as follows: 70% -100%;
s403: the heat preservation temperature is as follows: 730 ℃ and 780 ℃, and the heat preservation time is as follows: 15-30 min;
s404: the centrifugal casting speed is as follows: 300-.
As an embodiment of the present invention, the heat treatment stage in step S5 includes:
s501: the solid solution treatment adopts two-stage solid solution treatment. The solid solution temperature is 300-;
s502: the aging temperature is as follows: 80-250 ℃ and aging time of 1-24h, and then obtaining the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy.
The technical scheme provided by the invention at least brings the following beneficial effects:
in the scheme, the multielement microalloying high-strength steel provided by the inventionThe die biphase magnesium-lithium alloy has specific micro metallographic structure appearance, as-cast structure grain refinement, Mg3Nd，Mg5Gd、Al8Mn5The phase is distributed in the grain boundary, and obviously, the grains are refined and dispersed.
The invention controls the content and the proportion of the Li element and the multi-element alloying element to ensure that the Li element and the multi-element alloying element exist in the matrix at the same time
Two-phase matrix phase, BCC with darker color in metallographic picture
Improves the elongation and plasticity of the alloy, and simultaneously improves the HCP-
The phase improves the strength of the alloy. Meanwhile, under the condition of ensuring the low density of the alloy, alloying elements such as Al, Zn, Mn, Gd, Y, Nd, Sn, Pr and the like are added, so that the effect of solid solution strengthening can be achieved, high-modulus precipitation strengthening phases can be generated in the matrix, and the phases are in crystal boundary and BCC-
The phase formation can block dislocation movement and slippage, and the strength and plasticity of the magnesium-lithium alloy can be greatly improved by combining various modes such as solution treatment, aging heat treatment and the like, and the elastic modulus of the magnesium-lithium alloy is also greatly improved by the high-modulus second phases. The multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy and the preparation method thereof provided by the invention can obtain the high-strength high-modulus two-phase magnesium-lithium alloy by adding multi-element alloying elements under the condition of ensuring the low density of the magnesium-lithium alloy, and are suitable for meeting the industrial requirements of light-weight, high-strength and high-toughness lithium-magnesium alloys.
By simultaneously adding rare earth elements Gd, Y, Nd and Pr, the invention not only can refine crystal grains and avoid partial aggregation of alloy components, but also can form Al with fine dispersion distribution and high modulus2Y（Gd，Pr）、MgZn2Gd（Y）、Mg3Nd、Al3Pr and the like to obviously improve the elastic modulus of the alloy. Simultaneous collaboration
-Mg and
the Li matrix phase improves the mechanical properties of the magnesium-lithium alloy, such as strength, plasticity, modulus and the like. And rare earth elements are added, so that the texture formed in the plastic deformation process can be weakened, and a fine grain structure is formed. Moreover, the rare earth elements are added, so that impurity elements in the melt can be purified, and the corrosion resistance of the alloy is improved.
The invention can form MgLi by adding Al and Zn simultaneously2Al and MgLi2The Zn phase improves the strength of the alloy, and can also generate a stable phase and a quasicrystal phase to further improve the mechanical property and the elongation of the magnesium-lithium alloy. Simultaneously, Mn and Sn elements are added to improve the yield strength of the magnesium-lithium alloy, remove harmful metal impurities, refine crystal grains and form a high-modulus strengthening phase Al with Al8Mn5With Li to form Li17Sn4High modulus phase.
In addition, the added Al may form Al with Li3The high modulus phase of Li and AlLi is cooperated with the multiple alloying elements through fine grain strengthening, solid solution strengthening, dispersion strengthening, second phase strengthening and the like to obtain the multiple microalloying high-strength high-modulus two-phase magnesium-lithium alloy.
The preparation method of the multi-element microalloyed high-strength high-modulus biphase magnesium-lithium alloy provided by the invention adopts the vacuum centrifugal smelting, multi-element microalloying and heat treatment processes to form a precipitated phase with high modulus, solid solution strengthening, fine grain strengthening and other coupling modes to improve the mechanical properties of the alloy, such as strength and the like.
The properties of the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy are as follows: the density is 1.3-1.9g/cm3Tensile strengthIs 280-430MPa, the yield strength is 240-360MPa, the elongation is 15-35 percent and the elastic modulus is 60-75 GPa.
In a word, the method adopts a mode of combining centrifugal casting, multi-element microalloying and heat treatment, has the advantages of low price, high efficiency, advanced and simple process, high raw material yield, wide application range and the like, can ensure the low density and light weight of the magnesium-lithium alloy, obviously improves the mechanical properties of strength, elongation, elastic modulus, plasticity and the like of the multi-element microalloyed dual-phase magnesium-lithium alloy, and can meet the requirements of the fields of military affairs, medical treatment, aviation and the like on light-weight high-strength high-modulus alloy materials.
Drawings
FIG. 1 is an as-cast microstructure of a multi-component microalloyed high strength high modulus two-phase magnesium lithium alloy of example 1 of the invention;
FIG. 2 is an as-cast microstructure of the multi-component microalloyed high strength high modulus two-phase magnesium lithium alloy of example 2 of the invention;
FIG. 3 is an as-cast microstructure of the multi-component microalloyed high strength high modulus two-phase magnesium lithium alloy of example 3 of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in further detail below.
Example 1
The multielement microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following elements in percentage by mass: al: 2wt.%, Gd: 0.9wt.%, Y: 3wt.%, Li: 6.5wt.%, Zn: 2wt.%, Mn: 0.5wt.%, Sn: 0.2wt.%, Pr: 0.2wt.%, Nd: 1wt.%, the balance Mg and unavoidable impurities; wherein: the inevitable impurity content
0.03wt%。
The preparation method of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following steps:
s1, selecting raw materials
Weighing 2wt.% of pure Al, 2wt.% of pure Zn, 0.2wt.% of pure Sn, 6.5wt.% of Li-containing Mg-20wt.% of Li intermediate alloy, 0.9wt.% of Gd-containing Mg-30wt.% of Gd intermediate alloy, 3wt.% of Y-containing Mg-30wt.% of Y intermediate alloy, 0.5wt.% of Mn-8 wt.% of Mn intermediate alloy, 0.2wt.% of Pr-25 wt.% of Pr intermediate alloy and 1wt.% of Nd-containing Mg-25wt.% of Nd intermediate alloy as raw materials according to the component and the mass percentage of the components in the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy, and polishing surface oxides by using a grinding machine to keep metallic luster for later use;
s2, stage of preheating raw material
Wrapping the raw materials weighed in the step S1 with aluminum foil, putting the raw materials, a crucible and a metal copper mold into a heat treatment furnace for preheating at 200 ℃ for 2 hours for later use;
s3, charging stage
Firstly, putting the crucible and the metal copper mold preheated in the step S2 into a vacuum centrifugal casting furnace protected by argon, then putting the preheated raw materials into the furnace, and putting the raw materials into different positions of the crucible in the centrifugal casting furnace according to factors such as the melting point, the easy oxidation degree, the density, the adding amount, the volatile degree and the like of the raw materials; considering that Li is relatively active and inflammable, and the upper part temperature is relatively low in the crucible heating process, small pure Mg blocks are placed at the bottom, then Mg-Gd, Mg-Y, Mg-Mn, Mg-Pr and Mg-Nd intermediate alloys are placed, pure Zn and pure Al are placed, and finally the Mg-Li intermediate alloy is placed; then the cold water circulator is opened and the furnace cover is closed, and the furnace atmosphere is vacuumized to 10 DEG-3Below Pa, then filling protective gas argon into the furnace;
s4 vacuum centrifugal smelting stage
After step S3, adjusting the heating current of the centrifugal casting furnace to 2.0A and the power to 50%, starting to heat and melt the raw material, heating to the red heat of the crucible at low power (50%), then heating to the raw material at high power (90%), starting to preserve heat, wherein the heat preservation temperature is 780 ℃, the heat preservation time is 15min, then setting the centrifugal casting speed to 350 r/min, and starting to cast to obtain the magnesium-lithium alloy ingot. Monitoring the temperature change in the furnace by adopting an infrared thermometer in the whole process;
s5, heat treatment stage
Putting the magnesium-lithium alloy cast ingot obtained in the step S4 into a vacuum tube furnace, and vacuumizing the furnace atmosphere to 10 DEG-3Introducing protective gas into the furnace until the gas pressure reaches the atmospheric pressure; carrying out a solid solution aging heat treatment process, wherein the solid solution temperature is as follows: the solid solution time is 5h at 350 ℃; the aging temperature is as follows: 100 ℃, and the aging time is as follows: and 5h, finally obtaining the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy.
The as-cast microstructure of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy is shown in figure 1, and the microstructure mainly comprises
-Mg，
-Li，Al2RE(Nd，Gd，Y，Pr)，Mg3(Nd, Pr, Sn)，Al8Mn5，AlLi，Mg24Y5，MgZn(Gd，Y)，Li17Sn4，MgLi2Al and MgLi2Zn, of which
The proportion of the phases is 60 percent,
the proportion of the phases is 30 percent; the comprehensive properties are as follows: the density was 1.65g/cm3The tensile strength was 351MPa, the yield strength was 283MPa, the elongation was 21.2%, and the elastic modulus was 65.8 GPa.
Example 2
The multielement microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following elements in percentage by mass: al: 4wt.%, Gd: 0.5wt.%, Y: 3wt.%, Li: 5wt.%, Zn: 2wt.%, Mn: 0.8wt.%, Sn: 0.9wt.%, Pr: 0.2wt.%, Nd: 0.5wt.%, the balance Mg and inevitable impurities; wherein: the inevitable impurity content
0.03wt%。
The preparation method of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following steps:
s1, selecting raw materials
Weighing 4wt.% of pure Al, 2wt.% of pure Zn, 0.9wt.% of pure Sn, 5wt.% of Li-containing Mg-30wt.% of Li intermediate alloy, 0.5wt.% of Gd-containing Mg-30wt.% of Gd intermediate alloy, 3wt.% of Y-containing Mg-30wt.% of Y intermediate alloy, 0.8wt.% of Mn-10 wt.% of Mn intermediate alloy, 0.2wt.% of Pr-25 wt.% of Pr intermediate alloy and 0.5wt.% of Nd-30 wt.% of Nd intermediate alloy as raw materials according to the component compositions and the mass percentages thereof in the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy, and grinding the surface oxide by using a grinding machine to keep the metallic luster for the later use;
s2 stage of preheating raw materials
Wrapping the raw materials weighed in the step S1 with aluminum foil, putting the raw materials, a crucible and a metal copper mold into a heat treatment furnace for preheating at 150 ℃ for 2 hours for later use;
s3, charging stage
Firstly, putting the crucible and the metal copper mold preheated in the step S2 into a vacuum centrifugal casting furnace protected by argon, then putting the preheated raw materials into the furnace, and putting the raw materials into different positions of the crucible in the centrifugal casting furnace according to factors such as the melting point, the easy oxidation degree, the density, the adding amount, the volatile degree and the like of the raw materials; considering that Li is more active and flammable and the upper temperature is relatively low in the crucible heating process, small pure Mg blocks are placed at the bottom, then Mg-Gd, Mg-Y, Mg-Mn, Mg-Pr and Mg-Nd intermediate alloys are placed, pure Zn and pure Al are placed, and finally the Mg-Li intermediate alloy is placed; then the cold water circulator is opened and the furnace cover is closed, and the furnace atmosphere is vacuumized to 10 DEG-3Below Pa, then filling protective gas argon into the furnace;
s4 vacuum centrifugal smelting stage
After step S3, adjusting the heating current of the centrifugal casting furnace to 2.5A and the power to 60%, starting to heat and melt the raw material, heating the raw material at low power (60%) until the crucible is red hot, heating the raw material at high power (95%) until the raw material is melted, starting to preserve heat, keeping the temperature at 730 ℃ for 30min, setting the centrifugal casting speed at 400 rpm, and starting to pour to obtain the magnesium-lithium alloy ingot. Monitoring the temperature change in the furnace by adopting an infrared thermometer in the whole process;
s5, heat treatment stage
Putting the magnesium-lithium alloy cast ingot obtained in the step S4 into a vacuum tube furnace, and vacuumizing the furnace atmosphere to 10 DEG-3Introducing protective gas into the furnace until the gas pressure reaches the atmospheric pressure; carrying out a solid solution aging heat treatment process, wherein the solid solution temperature is as follows: the solid solution time is 6h at 360 ℃; the aging temperature is as follows: at 120 ℃, the aging time is as follows: and 3h, finally obtaining the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy.
The as-cast microstructure of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy is shown in figure 2, and the microstructure mainly comprises
-Mg，
-Li，Al2RE(Gd，Y，Pr)，Mg3(Nd, Pr, Sn)，Al8Mn5，AlLi，Mg24Y5，MgZn(Gd，Y，Sn)， Li17Sn4，MgLi2Al and MgLi2Zn, of which
The proportion of the phases is 74 percent,
the proportion of the phases is 20 percent; the comprehensive properties are as follows: the density was 1.55g/cm3The tensile strength was 300MPa, the yield strength was 260MPa, the elongation was 21.2%, and the elastic modulus was 68 GPa.
Example 3
The multielement microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following elements in percentage by mass: al: 4wt.%, Gd: 1wt.%, Y: 1.5wt.%, Li: 6wt.%, Zn: 2.5wt.%, Mn: 0.6wt.%, Sn: 0.2wt.%, Pr: 1wt.%, Nd: 0.5wt.%, balance Mg and unavoidable impuritiesFree impurities; wherein: the inevitable impurity content
0.03wt%。
The preparation method of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following steps:
s1, selecting raw materials
Weighing 4wt.% of pure Al, 2.5wt.% of pure Zn, 0.2wt.% of pure Sn, 6wt.% of Li-containing Mg-20wt.% of Li intermediate alloy, 1wt.% of Gd-containing Mg-30wt.% of Gd intermediate alloy, 1.5wt.% of Y-containing Mg-30wt.% of Y intermediate alloy, 0.6wt.% of Mn-10 wt.% of Mn intermediate alloy, 1wt.% of Pr-25 wt.% of Pr intermediate alloy and 0.5wt.% of Nd intermediate alloy as raw materials according to the component compositions and the mass percentages thereof in the multi-component microalloyed high-strength high-modulus two-phase magnesium-lithium alloy, and polishing surface oxides by using a grinding machine to keep metallic luster for later use;
s2, stage of preheating raw material
Wrapping the raw materials weighed in the step S1 with aluminum foil, putting the raw materials, a crucible and a metal copper mold into a heat treatment furnace for preheating at 200 ℃ for 1h, and keeping the raw materials for later use;
s3, charging stage
Firstly, putting the crucible and the metal copper mold preheated in the step S2 into a vacuum centrifugal casting furnace protected by argon, then putting the preheated raw materials into the furnace, and putting the raw materials into different positions of the crucible in the centrifugal casting furnace according to factors such as the melting point, the easy oxidation degree, the density, the adding amount, the volatile degree and the like of the raw materials; considering that Li is more active and flammable and the upper temperature is relatively low in the crucible heating process, small pure Mg blocks are placed at the bottom, then Mg-Gd, Mg-Y, Mg-Mn, Mg-Pr and Mg-Nd intermediate alloys are placed, pure Zn and pure Al are placed, and finally the Mg-Li intermediate alloy is placed; then the cold water circulator is opened and the furnace cover is closed, and the furnace atmosphere is vacuumized to 10 DEG-3Below Pa, then filling protective gas argon into the furnace;
s4 vacuum centrifugal smelting stage
After step S3, adjusting the heating current of the centrifugal casting furnace to be 3A and the power to be 50%, starting to heat and melt the raw material, firstly heating the raw material at low power (50%) until the crucible is red hot, then heating the raw material at high power (95%) until the raw material is melted, starting to preserve heat, setting the heat preservation temperature to be 780 ℃, preserving the heat for 30min, then setting the centrifugal casting speed to be 400 r/min, and starting to pour to obtain the magnesium-lithium alloy ingot. Monitoring the temperature change in the furnace by adopting an infrared thermometer in the whole process;
s5, heat treatment stage
Putting the magnesium-lithium alloy cast ingot obtained in the step S4 into a vacuum tube furnace, and vacuumizing the furnace atmosphere to 10 DEG-3Introducing protective gas into the furnace until the gas pressure reaches the atmospheric pressure; carrying out a solid solution aging heat treatment process, wherein the solid solution temperature is as follows: the solid solution time is 8h at 350 ℃; the aging temperature is as follows: at 80 ℃, the aging time is as follows: and 5h, finally obtaining the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy.
The as-cast microstructure of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy is shown in FIG. 3, and the microstructure mainly comprises
-Mg，
-Li，Al2RE(Nd，Gd，Y，Pr)，Mg3(Nd, Pr, Sn)，Al8Mn5，AlLi，Mg24Y5，MgZn(Gd，Y)，Li17Sn4，MgLi2Al and MgLi2Zn, of which
The proportion of the phases is 55 percent,
the proportion of the phases is 41 percent; the comprehensive properties are as follows: the density was 1.69g/cm3The tensile strength was 330MPa, the yield strength was 283MPa, the elongation was 23%, and the elastic modulus was 65 GPa.
Example 4
Multi-element microalloying high-strength steelThe high-modulus two-phase magnesium-lithium alloy comprises the following elements in percentage by mass: al: 3wt.%, Gd: 1.5wt.%, Y: 3wt.%, Li: 10wt.%, Zn: 2.5wt.%, Mn: 0.8wt.%, Sn: 0.5wt.%, Pr: 1wt.%, Nd: 0.4wt.%, the balance Mg and inevitable impurities; wherein: the inevitable impurity content
0.03wt%。
The preparation method of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following steps:
s1, selecting raw materials
Weighing 3wt.% of Al pure Al, 2.5wt.% of Zn pure Zn, 0.5wt.% of Sn pure Sn, 10wt.% of Li-containing Mg-20wt.% of Li intermediate alloy, 1.5wt.% of Gd-containing Mg-30wt.% of Gd intermediate alloy, 3wt.% of Y-containing Mg-30wt.% of Y intermediate alloy, 0.8wt.% of Mn-10 wt.% of Mn intermediate alloy, 1wt.% of Pr-25 wt.% of Pr intermediate alloy, and 0.4wt.% of Nd-25 wt.% of Nd intermediate alloy as raw materials, grinding surface oxides by using a grinding machine, keeping metallic luster, and keeping the use in the later step;
s2 stage of preheating raw materials
Wrapping the raw materials weighed in the step S1 with aluminum foil, putting the raw materials, a crucible and a metal copper mold into a heat treatment furnace for preheating at 180 ℃ for 1h, and keeping the raw materials for later use;
s3, charging stage
Firstly, putting the crucible and the metal copper mold preheated in the step S2 into a vacuum centrifugal casting furnace protected by argon, then putting the preheated raw materials into the furnace, and putting the raw materials into different positions of the crucible in the centrifugal casting furnace according to factors such as the melting point, the easy oxidation degree, the density, the adding amount, the volatile degree and the like of the raw materials; considering that Li is more active and flammable and the upper temperature is relatively low in the crucible heating process, small pure Mg blocks are placed at the bottom, then Mg-Gd, Mg-Y, Mg-Mn, Mg-Pr and Mg-Nd intermediate alloys are placed, pure Zn and pure Al are placed, and finally the Mg-Li intermediate alloy is placed; then opening the cold water circulator, covering the furnace cover, and openingThe furnace atmosphere is vacuumized to 10-3Below Pa, then filling protective gas argon into the furnace;
s4 vacuum centrifugal smelting stage
After step S3, adjusting the heating current of the centrifugal casting furnace to 2.5A and the power to 60%, starting to heat and melt the raw material, heating the raw material at low power (60%) until the crucible is red hot, heating the raw material at high power (90%) until the raw material is melted, starting to preserve heat, keeping the temperature at 750 ℃ for 20min, setting the centrifugal casting speed at 450 rpm, and starting to pour to obtain the magnesium-lithium alloy ingot. Monitoring the temperature change in the furnace by adopting an infrared thermometer in the whole process;
s5, heat treatment stage
Putting the magnesium-lithium alloy cast ingot obtained in the step S4 into a vacuum tube furnace, and vacuumizing the furnace atmosphere to 10 DEG-3Introducing protective gas into the furnace until the gas pressure reaches the atmospheric pressure; carrying out a solid solution aging heat treatment process, wherein the solid solution temperature is as follows: the solid solution time is 8h at 350 ℃; the aging temperature is as follows: at 80 ℃, the aging time is as follows: and 5h, finally obtaining the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy.
The as-cast microstructure of the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy is mainly
-Mg，
-Li，Al2RE(Nd，Gd，Y，Pr)，Mg3(Nd, Pr, Sn)，Al8Mn5，AlLi，Mg24Y5，MgZn(Gd，Y)，Li17Sn4，MgLi2Al and MgLi2Zn, of which
The proportion of the phases is 40 percent,
the proportion of the phases is 55 percent; the overall performance is shown in fig. 2: the density was 1.75g/cm3The tensile strength was 351MPa, the yield strength was 270MPa, the elongation was 26%, and the elastic modulus was 66 GPa.
Example 5
The multielement microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following elements in percentage by mass: al: 3.5wt.%, Gd: 0.5wt.%, Y: 2.5wt.%, Li: 8wt.%, Zn: 1.5wt.%, Mn: 0.9wt.%, Sn: 0.5wt.%, Pr: 0.5wt.%, Nd: 0.6wt.%, the balance Mg and inevitable impurities; wherein: the inevitable impurity content
0.03wt%。
The preparation method of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following steps:
s1, selecting raw materials
Weighing 3.5wt.% of pure Al, 1.5wt.% of pure Zn, 0.5wt.% of pure Sn, 8wt.% of Li-containing Mg-20wt.% of Li intermediate alloy, 0.5wt.% of Gd-containing Mg-30wt.% of Gd intermediate alloy, 2.5wt.% of Y-containing Mg-30wt.% of Y intermediate alloy, 0.9wt.% of Mn-10 wt.% of Mn intermediate alloy, 0.5wt.% of Pr-25 wt.% of Pr intermediate alloy, and 0.6wt.% of Nd-containing Mg-25wt.% of Nd intermediate alloy as raw materials according to the component and the mass percentage of the component in the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy, and polishing surface oxides by using a grinding machine to keep metallic luster for later use;
s2 stage of preheating raw materials
Wrapping the raw materials weighed in the step S1 with aluminum foil, putting the raw materials, a crucible and a metal copper mold into a heat treatment furnace for preheating at 200 ℃ for 2 hours for later use;
s3, charging stage
Firstly, putting the crucible and the metal copper mold preheated in the step S2 into a vacuum centrifugal casting furnace protected by argon, then putting the preheated raw materials into the furnace, and putting the raw materials into different positions of the crucible in the centrifugal casting furnace according to factors such as the melting point, the easy oxidation degree, the density, the adding amount, the volatile degree and the like of the raw materials; wherein Li is considered to be more active and inflammable, and the upper part of the crucible is heatedThe temperature is relatively low, so small pure Mg blocks are placed at the bottom, then intermediate alloys of Mg-Gd, Mg-Y, Mg-Mn, Mg-Pr and Mg-Nd are placed, pure Zn and pure Al are placed, and finally the intermediate alloy of Mg-Li is placed; then the cold water circulator is opened and the furnace cover is closed, and the furnace atmosphere is vacuumized to 10 DEG-3Below Pa, then filling protective gas argon into the furnace;
s4 vacuum centrifugal smelting stage
After step S3, adjusting the heating current of the centrifugal casting furnace to 4.5A and the power to 50%, starting to heat and melt the raw material, heating to the red heat of the crucible at low power (50%), then heating to the raw material at high power (99%), starting to preserve heat, preserving the heat at 730 ℃ for 30min, setting the centrifugal casting speed at 450 rpm, and starting to cast to obtain the magnesium-lithium alloy ingot. Monitoring the temperature change in the furnace by adopting an infrared thermometer in the whole process;
s5, heat treatment stage
Putting the magnesium-lithium alloy cast ingot obtained in the step S4 into a vacuum tube furnace, and vacuumizing the furnace atmosphere to 10 DEG-3Below Pa, introducing protective gas into the furnace until the gas pressure reaches the atmospheric pressure; carrying out a solid solution aging heat treatment process, wherein the solid solution temperature is as follows: the solid solution time is 5h at 340 ℃; the aging temperature is as follows: at 150 ℃, the aging time is as follows: and 3h, finally obtaining the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy.
The as-cast microstructure of the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy is mainly
-Mg，
-Li，Al2RE(Nd，Gd，Y，Pr)，Mg3(Nd, Pr, Sn)，Al8Mn5，AlLi，Mg24Y5，MgZn(Gd，Y)，Li17Sn4，MgLi2Al and MgLi2Zn, of which
The proportion of the phases is 48 percent,
the proportion of the phases is 44%; the comprehensive performance is shown in figure 2: the density was 1.78g/cm3The tensile strength was 345MPa, the yield strength was 280MPa, the elongation was 23%, and the elastic modulus was 70 GPa.
Example 6
The multielement microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following elements in percentage by mass: al: 2.5wt.%, Gd: 1wt.%, Y: 1.5wt.%, Li: 12wt.%, Zn: 2wt.%, Mn: 0.5wt.%, Sn: 0.5wt.%, Pr: 0.9wt.%, Nd: 1wt.%, the balance Mg and unavoidable impurities; wherein: the inevitable impurity content
0.03wt%。
The preparation method of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following steps:
s1, selecting raw materials
Weighing 2.5wt.% of pure Al, 2.5wt.% of pure Zn, 0.5wt.% of pure Sn, 12wt.% of Li-containing Mg-20wt.% of Li intermediate alloy, 1wt.% of Gd-containing Mg-30wt.% of Gd intermediate alloy, 1.5wt.% of Y-containing Mg-30wt.% of Y intermediate alloy, 0.5wt.% of Mn-10 wt.% of Mn intermediate alloy, 0.9wt.% of Pr-20 wt.% of Pr intermediate alloy and 1wt.% of Nd-containing Mg-30wt.% of Nd intermediate alloy as raw materials according to the component and the mass percentage of the components in the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy, and polishing surface oxides by using a grinding machine to keep metallic luster for later use;
s2 stage of preheating raw materials
Wrapping the raw materials weighed in the step S1 with aluminum foil, putting the raw materials, a crucible and a metal copper mold into a heat treatment furnace for preheating at 150 ℃ for 2 hours for later use;
s3, charging stage
The crucible and the metal copper mold preheated in the step S2 are firstly put into a vacuum centrifugal casting furnace with argon protection, and then the preheated raw materials are put into the furnacePutting the raw materials into different positions of a crucible in a centrifugal casting furnace according to factors such as melting point, easy oxidation degree, density, adding amount, easy volatilization degree and the like of the raw materials; considering that Li is more active and flammable and the upper temperature is relatively low in the crucible heating process, small pure Mg blocks are placed at the bottom, then Mg-Gd, Mg-Y, Mg-Mn, Mg-Pr and Mg-Nd intermediate alloys are placed, pure Zn and pure Al are placed, and finally the Mg-Li intermediate alloy is placed; then the cold water circulator is opened and the furnace cover is closed, and the furnace atmosphere is vacuumized to 10 DEG-3Below Pa, then filling protective gas argon into the furnace;
s4 vacuum centrifugal smelting stage
After step S3, adjusting the heating current of the centrifugal casting furnace to be 4A and the power to be 60%, starting to heat and melt the raw material, firstly heating the raw material at low power (60%) until the crucible is red hot, then heating the raw material at high power (100%) until the raw material is melted, starting to preserve heat, setting the heat preservation temperature to be 780 ℃, the heat preservation time to be 20min, then setting the centrifugal casting speed to be 500 r/min, and starting to pour to obtain the magnesium-lithium alloy ingot. Monitoring the temperature change in the furnace by adopting an infrared thermometer in the whole process;
s5, heat treatment stage
Putting the magnesium-lithium alloy cast ingot obtained in the step S4 into a vacuum tube furnace, and vacuumizing the furnace atmosphere to 10 DEG-3Introducing protective gas into the furnace until the gas pressure reaches the atmospheric pressure; carrying out a solid solution aging heat treatment process, wherein the solid solution temperature is as follows: the solid solution time is 24 hours at 400 ℃; the aging temperature is as follows: at 120 ℃, the aging time is as follows: and 5h, finally obtaining the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy.
The as-cast microstructure of the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy is mainly
-Mg，
-Li，Al2RE(Nd，Gd，Y，Pr)，Mg3(Nd, Pr, Sn)，Al8Mn5，AlLi，Mg24Y5，MgZn(Gd，Y)，Li17Sn4，MgLi2Al and MgLi2Zn, of which
The proportion of the phases is 35 percent,
the proportion of the phases is 55 percent; the overall performance is shown in fig. 2: the density was 1.63g/cm3The tensile strength was 343MPa, the yield strength was 290MPa, the elongation was 25%, and the elastic modulus was 68 GPa.
In the scheme, the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy provided by the invention has the advantages of specific micro metallographic structure morphology, refined as-cast structure grains and Mg3Nd，Mg5Gd、Al8Mn5The phase is distributed in the grain boundary, and obviously, the grains are refined and dispersed.
The invention controls the content and the proportion of the Li element and the multi-element alloying element to ensure that the Li element and the multi-element alloying element exist in the matrix at the same time
Two-phase matrix phase, BCC-
The elongation and plasticity of the alloy are improved, and HCP-
The phase improves the strength of the alloy. Meanwhile, under the condition of ensuring the low density of the alloy, alloying elements such as Al, Zn, Mn, Gd Y, Nd, Sn, Pr and the like are added, so that the effect of solid solution strengthening can be achieved, high-modulus precipitation strengthening phases can be generated in the matrix, and the phases are in the crystal boundary and BCC-
The phase formation can block dislocation movement and slippage, and the combination of solution treatment, aging heat treatment and other ways can greatly improve the strength and plasticity of the magnesium-lithium alloy, and the second phase with high modulus is also greatly improvedThe modulus of elasticity of the magnesium-lithium alloy. The multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy and the preparation method thereof provided by the invention can obtain the high-strength high-modulus two-phase magnesium-lithium alloy by adding multi-element alloying elements under the condition of ensuring the low density of the magnesium-lithium alloy, and are suitable for meeting the industrial requirements of light weight, high strength and high toughness.
The invention can refine crystal grains, avoid the segregation of alloy components and form Al with fine dispersion distribution and high modulus by simultaneously adding rare earth elements (Gd, Y, Nd and Pr)2Y（Gd，Pr）、MgZn2Gd（Y）、Mg3Nd、Al3Pr and the like to obviously improve the elastic modulus of the alloy. Meanwhile, the alloy is cooperated with a-Mg and b-Li matrix phases to improve the mechanical properties of the magnesium-lithium alloy, such as strength, plasticity, modulus and the like. And rare earth elements are added, so that the texture formed in the plastic deformation process can be weakened, and a fine grain structure is formed. Moreover, the rare earth elements are added, so that impurity elements in the melt can be purified, and the corrosion resistance of the alloy is improved.
The invention can form MgLi by adding Al and Zn simultaneously2Al and MgLi2The Zn phase improves the strength of the alloy, and can also generate a stable phase and a quasicrystal phase to further improve the mechanical property and the elongation of the magnesium-lithium alloy. Simultaneously, Mn and Sn elements are added to improve the yield strength of the magnesium-lithium alloy, remove harmful metal impurities, refine crystal grains and form a high-modulus strengthening phase Al with Al8Mn5With Li to form Li17Sn4High modulus phase.
In addition, the added Al may form Al with Li3The high modulus phase of Li and AlLi is cooperated with the multiple alloying elements through fine grain strengthening, solid solution strengthening, dispersion strengthening, second phase strengthening and the like to obtain the multiple microalloying high-strength high-modulus two-phase magnesium-lithium alloy.
The preparation method of the multi-element microalloying high-strength high-modulus two-phase magnesium-lithium alloy provided by the invention adopts the vacuum centrifugal smelting, the multi-element microalloying and the heat treatment process to form the precipitated phase with high modulus, solid solution strengthening, fine grain strengthening and other coupling modes to improve the mechanical properties of the alloy, such as strength and the like.
The properties of the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy are as follows: the density is 1.3-1.9g/cm3The tensile strength is 280-430MPa, the yield strength is 240-360MPa, the elongation is 15-35 percent, and the elastic modulus is 60-75 GPa.
In a word, the method adopts a mode of combining centrifugal casting, multi-element microalloying and heat treatment, has the advantages of low price, high efficiency, advanced and simple process, high raw material yield, wide application range and the like, can ensure the low density and light weight of the magnesium-lithium alloy, obviously improves the mechanical properties of strength, elongation, elastic modulus, plasticity and the like of the multi-element microalloyed dual-phase magnesium-lithium alloy, and can meet the requirements of the fields of military affairs, medical treatment, aviation and the like on light-weight high-strength high-modulus alloy materials.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. The multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy is characterized in that the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy comprises the following elements in percentage by mass: al: 1-5wt.%, Gd: 0.1-2wt.%, Y: 0.5-3wt.%, Li: 5-12wt.%, Zn: 0.2-3wt.%, Mn: 0.1-0.8wt.%, Sn: 0.1-1.5wt.%, Pr: 0.1-1.5wt.%, Nd: 0.1-1.5wt.%, the balance Mg and impurities;
the content of the impurities
0.03wt%。
2. The multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy as claimed in claim 1, wherein the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy mainly has a structureIs composed of
-Mg，
-Li，Al2RE(Nd，Gd，Y，Pr)，Mg3(Nd, Pr, Sn)，Al8Mn5，AlLi，Mg24Y5，MgZn(Gd，Y)，Li17Sn4，MgLi2Al and MgLi2Zn；
Wherein,
-Mg in a proportion of 30-80%,
-a Li proportion of 30-70%,
phase C
The total proportion of phases does not exceed 95%.
3. The multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy as claimed in claim 1, wherein the properties of the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy are as follows: the density is 1.3-1.9g/cm3The tensile strength is 280-430MPa, the yield strength is 240-360MPa, the elongation is 15-35 percent, and the elastic modulus is 60-75 GPa.
4. A method for preparing the multi-microalloyed high-strength high-modulus two-phase magnesium-lithium alloy as defined in any one of claims 1 to 3, which comprises:
s1: raw material selection
According to the composition and the mass percentage of each element in the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy, pure Mg, pure Al, pure Zn, pure Sn, Mg-Li intermediate alloy, Mg-Gd intermediate alloy, Mg-Y intermediate alloy, Mg-Mn intermediate alloy, Mg-Pr intermediate alloy and Mg-Nd intermediate alloy are used as raw materials to be weighed, and a grinding machine is used for grinding surface oxides to keep the surface oxides in metallic luster for the next step;
s2: stage of preheating raw materials
Wrapping the raw materials weighed in the step S1 with aluminum foil, putting the wrapped raw materials, a crucible and a metal copper mold into a heat treatment furnace for preheating, and reserving for later use;
s3: charging phase
Firstly, placing the preheated crucible and the metal copper mold in the step S2 into a vacuum centrifugal casting furnace with argon protection, then placing the preheated raw materials into different positions of the crucible in the centrifugal casting furnace, then opening a cold water circulator and covering a furnace cover, and starting to vacuumize the atmosphere in the furnace to 10 DEG C-3Below Pa, then filling protective gas argon into the furnace;
s4: vacuum centrifugal smelting stage
After the step S3, adjusting the heating current and power of the centrifugal casting furnace, starting to heat and melt the raw material, firstly heating at low power until the crucible is red hot, then heating at high power until the raw material is melted, starting to preserve heat, then setting the centrifugal casting speed and starting to cast to obtain a magnesium-lithium alloy ingot, and monitoring the temperature change in the furnace by an infrared thermometer in the whole process;
s5: stage of heat treatment
Putting the magnesium-lithium alloy cast ingot obtained in the step S4 into a vacuum tube furnace, and vacuumizing the furnace atmosphere to 10 DEG-3Introducing protective gas into the furnace until the gas pressure reaches the atmospheric pressure; setting heat treatment temperature, and then carrying out solid solution aging heat treatment process to finally obtain the multi-element microalloyed high-strength high-modulus two-phase magnesium-lithium alloy.
5. The method of claim 4, wherein in step S1, the mass purities of pure Mg, pure Al, pure Sn and pure Zn are all 99.90-99.999%;
in step S1, the raw materials include Li, Gd, Y, Mn, Pr and Nd in the mass content of 10-50wt.% in the Mg-Li intermediate alloy, the Mg-Gd intermediate alloy, the Mg-Y intermediate alloy, the Mg-Mn intermediate alloy, the Mg-Pr intermediate alloy and the Mg-Nd intermediate alloy.
6. The method according to claim 4, wherein in step S2, the preheating temperature is 80-250 ℃, and the preheating time is 0.5-2 h;
in step S2, the crucible is: graphite crucibles, BN crucibles or stainless steel crucibles.
7. The method as claimed in claim 4, wherein in step S3, the crucible in the centrifugal casting furnace is placed at different positions according to the melting point, the degree of easy oxidation, the density, the amount of addition and the degree of easy volatilization of the raw material; in consideration of the fact that Li is active and flammable and the upper temperature is relatively low in the crucible heating process, small pure Mg blocks are placed at the bottom, then Mg-Gd, Mg-Y, Mg-Mn, Mg-Pr and Mg-Nd intermediate alloys are placed, pure Zn and pure Al are placed, and finally the Mg-Li intermediate alloy is placed.
8. The method of claim 4, wherein the vacuum centrifugal smelting stage of step S4 includes:
s401: the heating current is 1.0-5.0A, and the heating power is 50-100%;
s402: the raw materials are heated and melted by adopting a gradient heating mode, the raw materials are firstly heated to be red hot in a crucible at low power, and the power is as follows: 50% -70%; heating to melt by adopting high power, wherein the high power is as follows: 70% -100%;
s403: the heat preservation temperature is as follows: 730 ℃ and 780 ℃, and the heat preservation time is as follows: 15-30 min;
s404: the centrifugal casting speed is as follows: 300-.
9. The method according to claim 4, characterized in that the heat treatment stage in step S5 comprises:
s501: the solid solution treatment adopts two-stage solid solution treatment, the solid solution temperature is 300-;
s502: the aging temperature is as follows: aging for 1-24h at 80-250 deg.C to obtain the final product.
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