U.S. patent application number 16/756710 was filed with the patent office on 2021-03-04 for preparation method of a lithium-containing magnesium/aluminum matrix composite.
The applicant listed for this patent is NORTHEASTERN UNIVERSITY. Invention is credited to Lei BAO, Chunlong CHENG, Qichi LE, Xiaoqiang LI, Bowen MA, Liang REN.
Application Number | 20210062315 16/756710 |
Document ID | / |
Family ID | 1000004959537 |
Filed Date | 2021-03-04 |
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United States Patent
Application |
20210062315 |
Kind Code |
A1 |
LE; Qichi ; et al. |
March 4, 2021 |
PREPARATION METHOD OF A LITHIUM-CONTAINING MAGNESIUM/ALUMINUM
MATRIX COMPOSITE
Abstract
The present invention relates to a preparation method of a
lithium-containing magnesium/aluminum matrix composite. The
preparation method is performed according to the following steps:
(1) preparing magnesium ingots or aluminum ingots, preparing
lithium metal, and preparing flux and reinforcements; (2) heating
the flux to prepare flux melt, and adding the reinforcements to the
flux melt to prepare a liquid-solid mixture; (3) pouring the
liquid-solid mixture in a normal-temperature crucible, and
performing cooling to obtain a precursor; (4) preheating a
crucible, adding raw materials, and performing melting to form a
raw material melt; (5) controlling a temperature of the raw
material melt to 973-993K, adding the lithium metal, performing
stirring, adding the precursor, performing stirring and mixing,
raising temperature to 993-1013K, and performing standing; and (6)
scumming operation should be carried out, and performing
temperature casting on composite melt.
Inventors: |
LE; Qichi; (Shenyang City,
Liaoning Province, CN) ; REN; Liang; (Shenyang City,
Liaoning Province, CN) ; LI; Xiaoqiang; (Shenyang
City, Liaoning Province, CN) ; CHENG; Chunlong;
(Shenyang City, Liaoning Province, CN) ; BAO; Lei;
(Shenyang City, Liaoning Province, CN) ; MA; Bowen;
(Shenyang City, Liaoning Province, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NORTHEASTERN UNIVERSITY |
Shenyang City, Liaoning Province |
|
CN |
|
|
Family ID: |
1000004959537 |
Appl. No.: |
16/756710 |
Filed: |
September 3, 2019 |
PCT Filed: |
September 3, 2019 |
PCT NO: |
PCT/CN2019/104189 |
371 Date: |
April 16, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 1/03 20130101; C22C
32/0036 20130101; C22C 49/04 20130101; C22C 32/0052 20130101; C22C
49/14 20130101; C22C 47/08 20130101 |
International
Class: |
C22C 47/08 20060101
C22C047/08; C22C 1/03 20060101 C22C001/03; C22C 32/00 20060101
C22C032/00; C22C 49/04 20060101 C22C049/04; C22C 49/14 20060101
C22C049/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2019 |
CN |
201910807579.5 |
Claims
1. A preparation method of a lithium-containing magnesium/aluminum
matrix composite, comprising the following steps: (1) preparing
magnesium ingots or aluminum ingots as raw materials, preparing
lithium metal, and preparing flux and reinforcements, wherein the
flux contains components in percentage by mass of 65%-85% of
lithium chloride, 15%-35% of lithium fluoride and less than or
equal to 20% of lithium bromide, the reinforcements are elemental
metal powder, rare earth oxide, carbide, boride or metal oxide, the
elemental metal powder is W, Mo or Ni, the rare earth oxide is
La.sub.2O.sub.3, CeO.sub.2 or Y.sub.2O.sub.3, the carbide is TiC or
SiC, the boride is ZrB.sub.2, and the metal oxide is MgO or
SiO.sub.2, the reinforcements are 0.1%-30% of total volume of the
raw materials, the reinforcements are 1%-50% of total volume of the
flux, and the lithium metal is 0.1%-10% of total mass of the raw
materials; (2) putting the flux into a clay crucible or a graphite
crucible, performing heating to 673-773K to make a flux melt,
adding the reinforcements to the flux melt, and performing stirring
to enable the reinforcements to uniformly disperse to make a
liquid-solid mixture; (3) pouring the liquid-solid mixture into the
clay crucible or the graphite crucible at normal temperature, and
performing cooling to normal temperature to obtain a precursor; (4)
preheating a crucible to 473-523K, then placing the raw materials
in the crucible, and enabling the raw materials to melt at 923-1023
K to form a raw material melt, wherein if the raw materials are the
magnesium ingots, the crucible is an iron crucible, and if the raw
materials are aluminum ingots, the crucible is a graphite crucible;
(5) controlling a temperature of the raw material melt at 973-993K,
putting the lithium metal wrapped with tin foil in the raw material
melt, performing uniform stirring and mixing, adding a precursor,
continuing to perform uniform stirring and mixing, raising
temperature to 993-1013K, and performing standing to separate
impurity components from composite components to form scumming and
composite melt; and (6) Scumming operation should be carried out on
a surface of the composite melt, then reducing a temperature of the
composite melt to 983.+-.5K, and performing casting to prepare the
lithium-containing magnesium/aluminum matrix composite.
2. The preparation method of claim 1, wherein purity of the
aluminum ingots is greater than or equal to 99.8%, purity of the
magnesium ingots is greater than or equal to 99.85%, and purity of
the lithium metal is greater than or equal to 99.8%.
3. The preparation method of claim 1, wherein the reinforcements
are in the form of fibers, particles or whiskers, wherein a
particle size of the particles is 300 nm to 20 .mu.m; the whisker
has a diameter of 0.1-1 .mu.m and a length of 10-100 .mu.m; and the
fibers have a diameter of 5-20 .mu.m and a continuous length of
10-70 mm.
4. The preparation method of claim 1, wherein in the step (2), a
stirring speed is 100-200 r/min, and a time is 5-10 min.
5. The preparation method of claim 1, wherein in the step (5), a
stirring speed is 100-300 r/min, and a time is 2-15 min.
6. The preparation method of claim 1, wherein in the step (5), a
standing time is 10-20 min.
7. The preparation method of claim 1, wherein in the step (1),
magnesium ingots/aluminum ingots and other metal components are
prepared as raw materials; when the step (4) is performed, the
magnesium ingots/aluminum ingots and the other metal components are
placed together in an iron crucible, melted, stirred and mixed
uniformly to form a raw material melt; when the magnesium ingots
and the other metal components are used as raw materials, the other
metal components are one or more of aluminum metal, zinc ingots,
manganese chloride, magnesium-rare earth alloys,
magnesium-zirconium alloys and magnesium-silicon alloys, and the
aluminum, zinc, manganese, rare earth, zirconium and silicon in
other metal components account for less than or equal to 10% of
total mass of the raw materials; and when aluminum ingots and other
metal components are used as raw materials, the other metal
components are one or more of magnesium metal, zinc ingots,
aluminum-manganese alloys, aluminum-rare earth alloys,
aluminum-copper alloys, aluminum-titanium alloys and
aluminum-silicon alloys, and the magnesium, zinc, manganese, rare
earth, copper, titanium and silicon in the other metal components
account for less than or equal to 10% of total mass of the raw
materials.
8. The preparation method of claim 1, wherein in the
lithium-containing magnesium/aluminum matrix composite, the
reinforcement component accounts for 0.1%-22% of total volume.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention belongs to the technical field of
preparation of metal materials, and particularly relates to a
preparation method of a lithium-containing magnesium/aluminum
matrix composite.
2. The Prior Arts
[0002] Magnesium-lithium alloys have the advantages of being low in
density, high in specific strength, and good in vibration damping
properties, electromagnetic shielding properties and machinability,
and are ideal materials with lightweight structure. In recent
years, great attention has been paid to research and application of
magnesium-lithium alloys. However, magnesium-lithium alloys also
have the problems of being difficult in plastic deformation, poor
in creep resistance at high temperature and poor in corrosion
resistance, wherein low strength, poor mechanical properties and
easy yield deformation are one of the important reasons that limit
the application field of magnesium-lithium alloys. Generally,
magnesium-lithium alloys cannot be used even as secondary stressed
members, but can only be used as housing parts, which severely
restrict the application field.
[0003] The aluminum-lithium alloys have the advantages of being low
in density, high in specific strength, high in specific rigidity,
and the like, the melting and casting properties of the
aluminum-lithium alloys are also better than those of traditional
aluminum alloys, and the aluminum-lithium alloys are also an ideal
material with lightweight structure. However, aluminum-lithium
alloys have serious anisotropy of mechanical properties, and low
plasticity and toughness and the like, so that the aluminum-lithium
alloys are inferior to other aluminum alloys.
[0004] Therefore, in order to expand the application range of
lightweight alloys, reinforcements with stable chemical properties
are often added to improve the mechanical properties of the
metallic composite materials.
[0005] Compared with traditional magnesium, aluminum alloys, the
magnesium and aluminum matrix composite not only has excellent
mechanical properties, but also has some special properties and
other good comprehensive properties. At present, methods for
preparing metallic composites mainly include a traditional
mechanical stirring casting method, a squeeze casting method, an
injection molding method, an in-situ reaction composite method, and
the like.
[0006] The method of powder metallurgy comprises the steps of
mixing the metal powder with the reinforcement powder by ball
milling, and then performing sinter molding by hot pressing under
the vacuum condition. By the powder metallurgy method, the matrix
alloys do not need to be heated to a molten state, so that the
matrix and the reinforcements can prevent the reaction at the
interface. After mixing, the reinforcements are uniformly
distributed in the matrix and play a good reinforcing role.
However, due to the large differences in size, shape and properties
between the reinforcements and the matrix alloys, compared with the
interface bonding strength of the composite produced by the casting
method, the interface bonding strength of the composite can be
reduced after bonding is performed. In addition, the process method
of powder metallurgy determines that the process method is more
suitable for small functional materials, but not for larger
structural materials. The process method is complicated and costly
in technological process, and many problems also exist in the
transportation process. Therefore, the method of powder metallurgy
greatly limits the preparation and production of light alloy matrix
composites as structural materials.
[0007] The traditional mechanical stirring casting method lies in
that reinforcements such as particles, whiskers and fibers are
added into a molten metal melt, and the reinforcements are
uniformly distributed in a matrix by the mechanical stirring
method. The traditional mechanical stirring casting method has the
advantages of being low in cost and simple in technological
process, can realize large-scale production and large-volume
production, and is widely applied in industries of aerospace,
automobile manufacturing and the like. How to uniformly distribute
the reinforcements in the metal melt is a key problem in the
preparation of light alloy composites. However, most of the
reinforcements tend to agglomerate or precipitate when entering the
molten metal melt due to its high surface energy or interfacial
tension, so that the reinforcements are difficult to uniformly
disperse in the melt. In addition, during the stirring process, gas
or oxide impurities can be mixed along with stirring, and the
particles of the reinforcements can increase the melt viscosity and
enable the gas to be difficult to escape, so that people have high
requirements for mechanical stirring, and the reason lies in
density differences between the reinforcements and metal melt,
which can inevitably lead to specific gravity segregation. If the
reinforcements have poor wettability to liquid metal, the
reinforcements cannot be well dispersed in the matrix.
[0008] The squeeze casting method is an accurate casting method
that enables liquid metal or semi-solid metal to be subjected to
mold filling and solidifying through the action of high pressure.
Firstly, the reinforcements are preformed, and then are heated,
molten metal or metal melt is poured in the heated reinforcements,
then pressing in of a mold is performed, and through cooling, a
composite casting is obtained. The squeeze casting method can
reduce influence of gas impurities on the quality of products, and
has low requirements for wettability. High integrity and uniform
castings can be obtained, the percentage by volume of the added
reinforcements is also increased by 30%-50%, and the properties of
the composite can also be notably improved. However, the problem
that pressure affects the casting quality also exists. When the
pressure is high, the molten melt can be turbulent, resulting in
oxidation and gas retention. When the pressure is small, part of
the gas cannot be removed, resulting in the phenomenon that the
casting is low integrity. In addition, the squeeze casting method
neither can be used for producing large-volume castings, nor can be
used for batch automated production.
[0009] The injection molding method lies in that inert gas is used
to atomize the molten metal for injection, the molten metal is
mixed with a reinforcement conveyed by the inert gas at the other
end, and the mixture is deposited and cooled on a platform to
obtain a metallic composite product. And the injection molding
method uses a metal rapid solidification technology to inhibit
grain growth and segregation formation, which enables grain
refinement and distribution of the reinforcements to be uniform.
Atomized metal and mixed deposition are two major influencing
factors of the injection molding method. The process of atomizing
metal is accompanied with gas transmission, which enables the
products often to have large porosity and shrinkage porosity. If
the solidification is too fast after deposition, the composite
effect of the reinforcements and the matrix is not good or even
does not occur. If solidification is slow, the reinforcements can
be unevenly distributed or even segregated. Moreover, as a novel
metallic composite preparation method, the injection molding method
has high cost, so that the injection molding method is not suitable
for automated batch production.
[0010] The in-situ reaction composite method is a novel method for
preparing the metal matrix composite. According to the method, the
reinforcements do not need to be directly added, but chemical
reactions or other special reactions are used to generate
reinforcements in the melt. Nucleation and growth are both
completed in the matrix, so that the phenomenon of incompatibility
or poor combination with the matrix does not exist, influence of
wetting conditions is avoided and the composite can be uniform and
pure. The method has the advantages of being low in cost, simple in
technological process, and quality of the obtained products is
high. However, the in-situ reaction composite method has the
limitation that only a small quantity of the reinforcements can be
added, so that requirements of batch production are also not
achieved.
[0011] For the selection of the reinforcements, attention needs to
be paid to whether there is good wettability between the
reinforcements and the matrix, whether the interface bonding
strength is appropriate, and whether chemical reaction exists at
the interface. At present, the reinforcements are roughly divided
into three types: whiskers, fibers and particles, such as lanthanum
oxide particles, cerium oxide particles, silicon carbide whiskers
and carbon fibers, wherein whiskers and particle reinforced
metallic composites have the advantages of being easy to process
and stable in size. In general, the reinforcements are high in
melting point and cannot melt when being added to the alloy melt,
and besides, cannot react chemically with the matrix. If the
reinforcements can uniformly exist in the matrix and segregation of
interstitial impurities at grain boundaries can be reduced, the
grain boundary strengthening can be improved. In addition, the
reinforcements as second phase exert the action of pinning for
dislocation and hinder the movement of the dislocation, so that the
strength of the alloys could be improved, and the plasticity cannot
be reduced too much. However, if the reinforcements are directly
added into the matrix melt, the particles can agglomerate due to
poor wettability and cannot be well dispersed in the matrix, so
that the dispersion strengthening effect cannot be achieved.
SUMMARY OF THE INVENTION
[0012] The present invention aims to provide a preparation method
of a lithium-containing magnesium/aluminum matrix composite. A
precursor of reinforcements was prepared by adding reinforcements
into the molten flux, and then the solidified precursor composed of
reinforcements wrapped with flux could be added easily to the
lithium-containing aluminum/magnesium alloy melt, which is due to
the relative low interfacial tension and high wettability between
the reinforcements and the flux, and between the flux and the
metallic matrix melt, so that the problem of the difficulty of
adding reinforcements to the alloys is solved. And the process is
simplified, and besides, the quality of the lithium-containing
aluminum/magnesium matrix composite is improved. This method can be
used to fabricate large-volume composites and large-size
components.
[0013] The method of the present invention is performed through the
following steps:
[0014] (1) Preparing magnesium ingots or aluminum ingots as raw
materials, preparing lithium metal, and preparing flux and
reinforcements, wherein the flux contains components in percentage
by mass of 65%-85% of lithium chloride, 15%-35% of lithium fluoride
and less than or equal to 20% of lithium bromide, the
reinforcements are elemental metal powder, rare earth oxide,
carbide, boride or metal oxide, the elemental metal powder is W, Mo
or Ni, the rare earth oxide is La.sub.2O.sub.3, CeO.sub.2 or
Y.sub.2O.sub.3, the carbide is TiC or SiC, the boride is ZrB.sub.2,
and the metal oxide is MgO or SiO.sub.2, the reinforcements are
0.1%-30% of total volume of the raw materials, the reinforcements
are 1%-50% of total volume of the flux, and the lithium metal is
0.1%-10% of total mass of the raw materials;
[0015] (2) Putting the flux into a clay crucible or a graphite
crucible, performing heating to 673-773K to make a flux melt,
adding the reinforcements to the flux melt, and performing stirring
to enable the reinforcements to uniformly disperse to make a
liquid-solid mixture;
[0016] (3) Pouring the liquid-solid mixture into the clay crucible
or the graphite crucible at normal temperature, and performing
cooling to normal temperature to obtain a precursor;
[0017] (4) Preheating crucible to 473-523K, then placing the raw
materials in the crucible, and enabling the raw materials to melted
at 923-1023 K to form a raw material melt, wherein if the raw
materials are the magnesium ingots, the crucible is an iron
crucible, and if the raw materials are aluminum ingots, the
crucible is a graphite crucible;
[0018] (5) Controlling a temperature of the raw material melt at
973-993K, putting the lithium metal wrapped with tin foil in the
raw material melt, performing uniform stirring and mixing, adding a
precursor, continuing to perform uniform stirring and mixing,
raising temperature to 993-1013K, and performing standing to
separate impurity components from composite components to form
scumming and composite melt; and
[0019] (6) Scumming operation should be carried out on a surface of
the composite melt, then reducing a temperature of the composite
melt to 983.+-.5K, and performing casting to prepare the
lithium-containing magnesium/aluminum matrix composite.
[0020] The purity of the aluminum ingots is greater than or equal
to 99.8%, purity of the magnesium ingots is greater than or equal
to 99.85%, and purity of the lithium metal is greater than or equal
to 99.8%.
[0021] The reinforcements are in the form of fibers, particles or
whiskers, wherein a particle size of the particles is 300 nm to 20
.mu.m; the whiskers have a diameter of 0.1-1 m and a length of
10-100 .mu.m; and the fibers have a diameter of 5-20 .mu.m and a
continuous length of 10-70 mm.
[0022] In the step (5), the precursor is firstly crushed to a
particle size of less than or equal to 5 cm and then put into the
raw material melt.
[0023] In the step (2), a stirring speed is 100-200 r/min, and a
time is 5-10 min.
[0024] In the step (5), a stirring speed is 100-300 r/min, and a
time is 2-15 min.
[0025] In the step (2), when the reinforcements are added to the
flux melt, all the reinforcements are added in 3-5 times, wherein
addition quantity each time is 50% or below of a total mass of the
reinforcements.
[0026] In the step (5), a standing time is 10-20 min.
[0027] In the step (5), before still standing, argon gas is used to
degas the materials in the crucible, the argon gas pressure is
0.2-0.5 MPa, and a degassing time is 2-5 min.
[0028] In the step (1), magnesium ingots/aluminum ingots and other
metal components are prepared as raw materials; when the step (4)
is performed, the magnesium ingots/aluminum ingots and the other
metal components are placed together in an iron crucible, melted,
stirred and mixed uniformly to form a raw material melt; when the
magnesium ingots and the other metal components are used as raw
materials, the other metal components are one or more of aluminum
metal, zinc ingots, manganese chloride, magnesium-rare earth
alloys, magnesium-zirconium alloys and magnesium-silicon alloys,
and the aluminum, zinc, manganese, rare earth, zirconium and
silicon in other metal components account for less than or equal to
10% of total mass of the raw materials; and when aluminum ingots
and other metal components are used as raw materials, the other
metal components are one or more of magnesium metal, zinc ingots,
aluminum-manganese alloys, aluminum-rare earth alloys,
aluminum-copper alloys, aluminum-titanium alloys and
aluminum-silicon alloys, and the magnesium, zinc, manganese, rare
earth, copper, titanium and silicon in the other metal components
account for less than or equal to 10% of total mass of the raw
materials.
[0029] In the lithium-containing magnesium/aluminum matrix
composite, the reinforcement component accounts for 0.1%-22% of
total volume.
[0030] The preparation method of the present invention is
characterized in that the reinforcements are put in the molten
flux, and are uniformly dispersed in molten flux through mechanical
stirring, and the wettability of the reinforcements is improved by
utilizing the good wetting property of the reinforcements and the
molten flux; the flux can effectively refine the melt, remove
impurities and cover the melt to prevent magnesium from
overburning; in addition, fluxes such as fluorine salt, chlorine
salt and bromine salt can improve the wettability of the
reinforcements, so that the reinforcements are easy to disperse
uniformly in the matrix; because the density of the selected molten
flux differs greatly from that of the melt, the reinforcements are
separated from the molten flux after being added to the melt; the
reinforcements after surface modification have good wettability
with the melt and can be uniformly dispersed in the melt; and as a
special alloy, lithium salt needs to be used as the flux. The
method provided by the present invention is simple in process and
low in cost, the strength of the light alloy composite can be
greatly improved, and the method can be used for preparing
large-volume light alloy composite structural parts, can be used
for automated production, and has important significance for
development of the aerospace industry.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is an SEM image of a composite product #1 in
embodiment 1 of the present invention;
[0032] FIG. 2 is an SEM image of a composite product #2 in
embodiment 1 of the present invention;
[0033] FIG. 3 is an SEM image of a composite product #3 in
embodiment 1 of the present invention;
[0034] FIG. 4 is an XRD image of a composite product #1 in
embodiment 1 of the present invention;
[0035] FIG. 5 is an XRD image of a composite product in embodiment
2 of the present invention; and
[0036] FIG. 6 is a metallograph of a composite product in
embodiment 2 of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0037] The present invention will be described in details below
with reference to embodiments.
[0038] In the embodiment of the present invention, thermocouples
are adopted to detect the temperature, thus ensuring the
temperature measurement accuracy.
[0039] Magnesium ingots, magnesium metal, aluminum ingots, aluminum
metal and lithium metal adopted in the embodiment of the present
invention are commercially available products.
[0040] The purities of lithium chloride, lithium bromide and
lithium fluoride adopted in the embodiment of the present invention
are commercially available analytical reagents.
[0041] The reinforcements adopted in the embodiment of the present
invention are commercially available products.
[0042] The electron microscope used in the embodiment of the
present invention is Shimadzu SSX550 from Japan.
[0043] The X-ray diffraction observation equipment adopted in the
embodiment of the present invention is PANalytical X'Pert Pro from
the Netherlands.
[0044] The metallographic microscope used in the embodiment of the
present invention is Leica 1600X.
[0045] The magnesium-rare earth alloys, magnesium-zirconium alloys
and magnesium-silicon alloys of the present invention are
collectively referred to as magnesium master alloys, and the rare
earth, zirconium and silicon in the magnesium master alloys
respectively account for 10%-40% of the total mass of the magnesium
master alloys.
[0046] The aluminum-manganese alloys, aluminum-rare earth alloys,
aluminum-copper alloys, aluminum-titanium alloys and
aluminum-silicon alloys of the present invention are collectively
referred to as aluminum master alloys, and manganese, rare earth,
copper, titanium and silicon in the aluminum master alloys
respectively account for 10%-40% of the total mass of the aluminum
master alloys.
[0047] According to the lithium-containing magnesium/aluminum
matrix composite in the embodiment of the present invention, X-ray
fluorescence spectrum analysis to calculate the percentage by mass
of the reinforcements, and then the percentage by mass is converted
into percentage by volume.
[0048] The purity of the aluminum ingots and the aluminum metal is
greater than or equal to 99.8%, the purity of magnesium ingots and
magnesium metal is greater than or equal to 99.85%, and the purity
of lithium metal is greater than or equal to 99.8%.
[0049] In the embodiment, the reinforcements are in the form of
fibers, particles or whiskers, wherein the particle size of the
particles is 300 nm to 20 .mu.m; the whisker has a diameter of
0.1-1 .mu.m and a length of 10-100 .mu.m; and the fibers have a
diameter of 5-20 .mu.m and a continuous length of 10-70 mm.
[0050] In the embodiment, before standing, argon gas is used to
degas the materials in the crucible, the used argon gas pressure is
0.2-0.5 MPa, and the degassing time is 2-5 min.
Embodiment 1
[0051] Magnesium ingots and other metal components are prepared as
raw materials, wherein the other metal components are aluminum
metal and zinc ingots, the mass ratio of the aluminum metal to the
zinc ingots is 1.5, and the aluminum metal and the zinc ingots
account for 5% of the total mass of the raw materials; lithium
metal is prepared; a flux and reinforcements are prepared; the flux
contains 75% of lithium chloride, 15% of lithium fluoride and 10%
of lithium bromide in percentage by mass; the reinforcements are
La.sub.2O.sub.3 particles of rare earth oxide; the reinforcements
are 0.5% of the total volume of the raw materials, the
reinforcements are 2% of the total volume of the flux, and the
lithium metal is 5% of the total mass of the raw materials;
[0052] The flux is put into a clay crucible, heating is performed
to 673K to make a flux melt, the reinforcements are added to the
flux melt, and stirring is performed to enable the reinforcements
to uniformly disperse to make a liquid-solid mixture, wherein the
stirring speed is 100 r/min, and the time is 10 min; when the
reinforcements are added to the flux melt, and all the
reinforcements are added in 3 times, wherein addition amount each
time is 50% or below of the total mass of the reinforcements;
[0053] The liquid-solid mixture is poured into the clay crucible at
normal temperature, and cooling is performed to normal temperature
to obtain a precursor;
[0054] The crucible is preheated to 473K, then the raw materials
are placed in a crucible, and the raw materials are melted at 923K
to form a raw material melt, wherein the crucible is an iron
crucible;
[0055] The temperature of the raw material melt is controlled to
973K; the lithium metal wrapped with tin foil is put in the raw
material melt, uniform stirring and mixing are performed, the
precursor is broken to the particle size less than or equal to 5 cm
and then put in the raw material melt, uniform stirring and mixing
are performed, then heating is performed to 993K, and standing is
performed to separate impurity components from composite components
to form scumming and composite melt, wherein the stirring speed is
100 r/min, the time is 15 min, and the standing time is 20 min;
[0056] Scumming on the surface of the composite melt is removed,
then the temperature of the composite melt is reduced to 983.+-.5K,
and casting is performed to prepare the lithium-containing
magnesium/aluminum matrix composite; the reinforcement component
accounts for 0.39% of the total volume, lithium accounts for 4.47%
of the total volume, and the rest is raw material components;
[0057] The percentage by volume of the reinforcements to the raw
materials is adjusted, and parallel tests are performed according
to the method, wherein the reinforcements respectively account for
1%, 3%, 5%, 7%, 9%, 15% and 20% of the total volume of the raw
materials;
[0058] The product prepared according to the scheme that the
reinforcements accounts for 0.5% of the total volume of the raw
materials is taken as the composite #1, and the rest is the,
composites #2, #3, #4, #5, #6, #7 and #8 in sequence. In the
magnesium matrix composite containing lithium, the reinforcements
are uniformly dispersed in the product, and the yield of the
reinforcements is 70%-90%, wherein SEM images of the composites #1,
#2 and #3 are shown in FIGS. 1, 2 and 3 respectively, and XRD
images of the composite #1 are shown in FIG. 4.
Embodiment 2
[0059] Difference between the method and the embodiment 1 lies in
that:
[0060] (1) Flux contains components in percentage by mass of 80% of
lithium chloride, 17% of lithium fluoride and 3% of lithium
bromide;
[0061] (2) The reinforcements are rare earth oxide and CeO.sub.2
particles;
[0062] (3) The reinforcements are 0.5% of the total volume of the
raw materials, the reinforcements are 1% of the total volume of the
flux, and the lithium metal is 4% of the total mass of the raw
materials;
[0063] (4) The flux is put into a clay crucible, heating is
performed to 773K to make a flux melt, the stirring speed is 200
r/min, the time is 5 min, the reinforcements are added to the flux
melt, and all of the reinforcements are added in 4 times;
[0064] (5) The crucible is preheated to 523K, then the raw
materials are placed in a crucible, and the raw materials are
melted at 1023K to form a raw material melt;
[0065] (6) The temperature of the raw material melt is controlled
to 983K, the temperature is raised to 1003K, standing is performed
for 15 min, the stirring speed is 300 r/min, and the time is 2
min;
[0066] (7) For the lithium-containing magnesium matrix composite,
reinforcement component accounts for 0.41% of the total volume,
lithium accounts for 3.26% of the total volume, and the rest is raw
material components.
[0067] The XRD image of the lithium-containing magnesium matrix
composite is shown in FIG. 5, and the metallographic examination
result is shown in FIG. 6.
Embodiment 3
[0068] Difference between the method and the embodiment 1 lies in
that:
[0069] (1) The magnesium ingots and other metal are prepared as raw
materials, other metal components are manganous chloride and
magnesium-rare earth alloys, manganous and rare earth in the other
metal components are 3% of the total mass of the raw materials, the
mass ratio of the rare earth to the manganous is 0.5, and the flux
contains components in percentage by mass of 85% of lithium
chloride and 15% of lithium fluoride;
[0070] (2) The reinforcements are elemental metal Mo;
[0071] (3) The reinforcements are 12% of the total volume of the
raw materials, the reinforcements are 20% of the total volume of
the flux, and the lithium metal is 1% of the total mass of the raw
materials;
[0072] (4) The flux is put into a clay crucible, heating is
performed to 723K to make a flux melt, the stirring speed is 150
r/min, the time is 8 min, the reinforcements are added to the flux
melt, and all of the reinforcements are added in 5 times;
[0073] (5) The crucible is preheated to 493K, then the raw
materials are placed in a crucible, and the raw materials are
melted at 973K to form a raw material melt;
[0074] (6) The temperature of the raw material melt is controlled
to 993K, the temperature is raised to 1013K, standing is performed
for 10 min, the stirring speed is 200 r/min, and the time is 8 min;
and
[0075] (7) For the lithium-containing magnesium matrix composite,
reinforcement component accounts for 9.8% of the total volume,
lithium accounts for 0.59% of the total volume, and the rest is raw
material components.
Embodiment 4
[0076] Difference between the method and the embodiment 1 lies in
that:
[0077] (1) Aluminum ingots and other metal components are prepared
as raw materials, other metal components are magnesium metal,
aluminum-copper alloys and aluminum-silicon alloys, magnesium,
copper and silicon in the other metal components are 10% of total
mass of the raw materials, the mass ratio of the magnesium to the
copper to the silicon is 1 to 0.4 to 0.6, and the flux contains
components in percentage by mass of 65% of lithium chloride and 35%
of lithium fluoride;
[0078] (2) The reinforcements are borides ZrB.sub.2;
[0079] (3) The reinforcements are 23% of the total volume of the
raw materials, the reinforcements are 40% of the total volume of
the flux, and the lithium metal is 10% of the total mass of the raw
materials;
[0080] (4) The flux is placed in the graphite crucible, and heating
is performed to 683K to make the flux melt;
[0081] (5) The liquid-solid mixture is poured in the graphite
crucible at normal temperature, and cooling is performed;
[0082] (6) The crucible is preheated to 483K, then the raw
materials are placed in a crucible, and the raw materials are
melted at 933K to form a raw material melt, wherein the crucible is
a graphite crucible;
[0083] (7) The temperature of the raw material melt is controlled
to 978K, the temperature is raised to 998K, standing is performed
for 12 min, the stirring speed is 150 r/min, and the time is 12
min; and
[0084] (8) The lithium-containing aluminum matrix composite is
made, wherein the reinforcement component accounts for 18.1% of the
total volume, lithium accounts for 6.97% of the total volume, and
the rest is raw material components.
Embodiment 5
[0085] Difference between the method and the embodiment 1 lies in
that:
[0086] (1) Aluminum ingots and other metal components are prepared
as raw materials, other metal components are aluminum-manganese
alloys, aluminum-rare earth alloys and aluminum-titanium alloys,
manganese, rare earth and titanium in the other metal components
are 4% of total mass of the raw materials, the mass ratio of the
manganese to the rare earth to the titanium is 1 to 0.2 to 0.4, and
the flux contains components in percentage by mass of 67% of
lithium chloride, 22% of lithium fluoride, and 11% of lithium
bromide;
[0087] (2) The reinforcements are carbides SiC;
[0088] (3) The reinforcements are 30% of the total volume of the
raw materials, the reinforcements are 50% of the total volume of
the flux, and the lithium metal is 6% of the total mass of the raw
materials;
[0089] (4) The flux is put into a graphite crucible, heating is
performed to 703K to make a flux melt, the stirring speed is 200
r/min, the time is 5 min, the reinforcements are added to the flux
melt, and all of the reinforcements are added in 4 times;
[0090] (5) The liquid-solid mixture is poured in the graphite
crucible at normal temperature, and cooling is performed;
[0091] (6) The crucible is preheated to 503K, then the raw
materials are placed in a crucible, and the raw materials are
melted at 983K to form a raw material melt, wherein the crucible is
a graphite crucible;
[0092] (7) The temperature of the raw material melt is controlled
to 988K, the temperature is raised to 1008K, standing is performed
for 14 min, the stirring speed is 250 r/min, and the time is 5 min;
and
[0093] (8) The lithium-containing aluminum matrix composite is
made, wherein the reinforcement component accounts for 22% of the
total volume, lithium accounts for 4.33% of the total volume, and
the rest is raw material components.
Embodiment 6
[0094] Difference between the method and the embodiment 1 lies in
that:
[0095] (1) Aluminum ingots are prepared as raw materials, and flux
contains components in percentage by mass of 76% of lithium
chloride, 18% of lithium fluoride and 6% of lithium bromide;
[0096] (2) The reinforcements are metallic oxides MgO;
[0097] (3) The reinforcements are 8% of the total volume of the raw
materials, the reinforcements are 16% of the total volume of the
flux, and the lithium metal is 3% of the total mass of the raw
materials;
[0098] (4) The flux is put into a graphite crucible, heating is
performed to 753K to make a flux melt, the stirring speed is 150
r/min, the time is 6 min, the reinforcements are added to the flux
melt, and all of the reinforcements are added in 5 times;
[0099] (5) The liquid-solid mixture is poured in the graphite
crucible at normal temperature, and cooling is performed;
[0100] (6) The crucible is preheated to 513K, then the raw
materials are placed in the crucible, and the raw materials are
melted at 1003K to form a raw material melt, wherein the crucible
is a graphite crucible;
[0101] (7) The temperature of the raw material melt is controlled
to 993K, the temperature is raised to 1013K, standing is performed
for 18 min, the stirring speed is 220 r/min, and the time is 6 min;
and
[0102] (8) The lithium-containing aluminum matrix composite is
made, wherein the reinforcement component accounts for 6.11% of the
total volume, lithium accounts for 1.49% of the total volume, and
the rest is raw material components.
* * * * *