U.S. patent application number 17/041902 was filed with the patent office on 2021-08-19 for preparation method for magnesium matrix composite.
The applicant listed for this patent is Northeastern University. Invention is credited to Lei BAO, Qichi LE, Xiaoqiang LI, Liang REN, Tong WANG, Dazhi ZHAO.
Application Number | 20210254194 17/041902 |
Document ID | / |
Family ID | 1000005613865 |
Filed Date | 2021-08-19 |
United States Patent
Application |
20210254194 |
Kind Code |
A1 |
LE; Qichi ; et al. |
August 19, 2021 |
PREPARATION METHOD FOR MAGNESIUM MATRIX COMPOSITE
Abstract
The invention relates to a preparation method for a magnesium
matrix composite. The preparation method comprises the following
steps: (1) preparing magnesium ingots as raw materials and salt
flux and reinforcements; (2) placing the salt flux in a crucible,
performing heating to prepare salt flux melts, adding the
reinforcements; (3) performing pouring into a normal-temperature
crucible, and performing cooling to obtain precursors; (4) adding
the raw materials in an iron crucible, and performing melting at
953K-1043K; (5) placing the precursors in raw material melt, after
stirring, under a condition of 953K-993K, performing standing so
that scum and melt are obtained; and (6) removing the scum,
lowering temperature to 973K-982K, and performing casting. The
method provided by the present invention is simple in process and
low in cost. The method can be used for preparing bulk structural
members of the magnesium matrix composite, and can be used for
automatic production.
Inventors: |
LE; Qichi; (Shenyang City,
Liaoning Province, CN) ; ZHAO; Dazhi; (Shenyang City,
Liaoning Province, CN) ; LI; Xiaoqiang; (Shenyang
City, Liaoning Province, CN) ; REN; Liang; (Shenyang
City, Liaoning Province, CN) ; BAO; Lei; (Shenyang
City, Liaoning Province, CN) ; WANG; Tong; (Shenyang
City, Liaoning Province, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Northeastern University |
Shenyang City, Liaoning Province |
|
CN |
|
|
Family ID: |
1000005613865 |
Appl. No.: |
17/041902 |
Filed: |
September 3, 2019 |
PCT Filed: |
September 3, 2019 |
PCT NO: |
PCT/CN2019/104192 |
371 Date: |
September 25, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 49/06 20130101;
C22C 1/1036 20130101; C22C 23/02 20130101; C22C 47/08 20130101 |
International
Class: |
C22C 1/10 20060101
C22C001/10; C22C 23/02 20060101 C22C023/02; C22C 49/06 20060101
C22C049/06; C22C 47/08 20060101 C22C047/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2019 |
CN |
201910808004.5 |
Claims
1. A preparation method for a magnesium matrix composite,
comprising: (1) preparing magnesium ingots as raw materials;
preparing salt flux and reinforcements, wherein the salt flux is a
mixture of barium chloride, magnesium chloride, sodium chloride and
calcium chloride, the barium chloride accounts for 35-50% of a
total mass of the salt flux, the magnesium chloride accounts for
10-20% of a total mass of the salt flux, the sodium chloride
accounts for 10-20% of a total mass of the salt flux, a balance is
the calcium chloride and impurities, the impurities account for no
more than 1% of the total mass of the salt flux, the reinforcements
are elementary metal, rare earth oxides, carbides, borides or metal
oxides, the elementary metal is W, Mo or Ni, the rare earth oxides
are La.sub.2O.sub.3, CeO.sub.2 or Y.sub.2O.sub.3, the carbides are
TiC or SiC, the borides are ZrB.sub.2, the metal oxides are MgO or
SiO.sub.2, the reinforcements are 0.1%-30% of a total volume of the
raw materials, and the reinforcements are 1%-50% of a total volume
of the salt flux; (2) placing the salt flux in a clay crucible or a
graphite crucible, performing heating to 773K-923K to prepare salt
flux melts, placing the reinforcements in the salt flux melts, and
performing stirring until the reinforcements are uniformly
dispersed to prepare a liquid-solid mixture; (3) pouring the
liquid-solid mixture into a normal-temperature clay crucible or
graphite crucible, and performing cooling to normal temperature to
obtain precursors; (4) preheating an iron crucible until a body of
the iron crucible is in a dark red heat, then placing the raw
materials in the iron crucible, and performing melting on the raw
materials at 953K-1043K to form a raw material melt; (5) placing
the precursors in the raw material melt of 953K-1043K, performing
stirring until the precursors are dispersed uniformly, under a
condition of 953-993K, adding refining agents, performing stirring
for refining, after the refining is finished, controlling
temperature to 1013K-1023K, and performing standing so that
impurity components are separated from composite components, and
scum and a composite melt are obtained; (6) removing the scum from
a surface of the composite melt, then cooling the composite melt to
973-982K, and performing casting to form the magnesium matrix
composite.
2. The preparation method according to claim 1, wherein a purity of
the magnesium ingots is greater than or equal to 99.85%.
3. The preparation method according to claim 1, wherein the
reinforcements are fibers, particles or whiskers, wherein a
particle size of the particles is 300 nm-20 .mu.m, a diameter of
the whiskers is 0.1 .mu.m-1 .mu.m, a length is 10 .mu.m-100 .mu.m,
a diameter of the fibers is 5 .mu.m-20 .mu.m, and a continuous
length is 10 mm-70 mm.
4. The preparation method according to claim 1, wherein in the step
(2), a stirring rate is 100 r/min-200 r/min, and a time is 2 min-10
min.
5. The preparation method according to claim 1, wherein in the step
(5), a stirring rate is 100 r/min-300 r/min, and a time is 5 min-15
min.
6. The preparation method according to claim 1, wherein in the step
(5), a standing time is 10 min-30 min.
7. The preparation method according to claim 1, further comprising
in the step (1): preparing the magnesium ingots and other metal
components as the raw materials; when the step (4) is performed,
placing the magnesium ingots and the other metal components in the
iron crucible jointly, performing melting, and preforming stirring
and uniform mixing to form a raw material melt, wherein the other
metal components are one or more of aluminum ingots, zinc ingots,
manganese chloride, magnesium-rare earth alloys,
magnesium-zirconium alloys and magnesium-silicon alloys, and
aluminum, zinc, manganese, rare earth, zirconium and silicon in the
other metal components account for no more than 10% of a total mass
of the raw materials.
8. The preparation method according to claim 1, further comprising
in the step (4): enabling covering flux to be scattered onto a
surface of the raw material melt so as to prevent magnesium from
burning, wherein the covering flux is No. 2 flux; when the step (5)
is performed, mixing the covering flux with the scum; and when the
step (6) is performed, removing the covering flux and the scum
together.
9. The preparation method according to claim 1, wherein in the step
(5), the refining agents are the No. 2 flux.
10. The preparation method according to claim 1, wherein raw
material components in the magnesium matrix composite account for
80-99.9% of a total volume, and components of the reinforcements
account for 0.1-20% of the total volume.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a preparation method for
composites, in particular to a preparation method for a magnesium
matrix composite.
2. The Prior Arts
[0002] Magnesium alloys have the advantages of being low in
density, high in specific strength, excellent in vibration-damping
performance, electromagnetic shielding performance and
machinability, and the like; the magnesium alloys are an ideal
material adopting a lightweight structure; and research and
application of the magnesium alloys are highly valued in recent
years. However, the magnesium alloys also have the shortcomings of
being high in melt casting difficulty, difficult in plastic
deformation, poor in high-temperature creep resistance, poor in
corrosion resistance and the like, wherein the low strength and
easy occurrence of yield deformation restrict the application of
the magnesium alloys; the magnesium alloys are generally applied to
secondary load-bearing components only, which restricts the
application field of the magnesium alloys severely; and therefore,
it is urgent to produce the lightweight magnesium matrix composite
having the advantages of being low in cost and high in
performance.
[0003] Compared with traditional magnesium and its alloys, the
magnesium matrix composite has some special performances and other
excellent comprehensive performances except for excellent
mechanical properties; and at present, methods for preparing a
reinforced magnesium matrix composite mainly comprise a traditional
mechanical stirring casting method, a squeeze casting method, an
injection molding method, an in-situ composite method, and the
like.
[0004] In the traditional mechanical stirring casting method,
particles, whiskers, fibers and other reinforcements are added to
molten metal melt, and the reinforcements are uniformly distributed
in matrices by a mechanical stirring method. The traditional
mechanical stirring casting method has the advantages of being low
in cost and simple in technological process, and can be used for
batch production and bulk production, and can be widely applied to
the industries, such as aerospace and automobile manufacturing. The
key problem for preparing the magnesium matrix composite is how to
distribute the reinforcements in the metal melt uniformly; however,
most of the reinforcements are often aggregated or precipitated
when entering into the molten metal melt, and accordingly are hard
to disperse in the metal melt uniformly; in the stirring process,
gas impurities can be mixed along with stirring, and the melt
viscosity can be increased by reinforcement particles, so that gas
is hard to escape; and therefore, there are very high requirements
for mechanical stirring. The reinforcements generate such
phenomenon in the melt that mainly because of density difference
between the reinforcements and metal, gravity segregation certainly
occurs; and because of the poor wettability of the reinforcements
for liquid metal, the reinforcements cannot be dispersed in the
matrices properly.
[0005] The squeeze casting method is a precision casting method
used for mold filling and solidification of the liquid metal or
semisolid metal under high pressure; firstly, the reinforcements
are preformed and heated, and then, molten metal or melt is poured,
and the reinforcements are pressed with molds, and cooled to obtain
composite castings. By the squeeze casting method, influence of the
gas impurities on product quality can be reduced, and low
requirements on wettability have been achieved; compact and uniform
castings can be prepared, and the volume fraction of the
reinforcements which can be added is also increased to 30%-50%; so
that the performance of the composite can be improved obviously.
However, the problem of influence of pressure on the casting
quality exists; under high pressure, molten magnesium can generate
turbulent flow, resulting in such phenomena of magnesium
oxidization and gas hold-up; and under low pressure, a part of gas
cannot be removed, resulting in the phenomenon that the castings
are not compact. In addition, the squeeze casting method cannot be
used for production of bulk castings or automatic batch
production.
[0006] In the injection molding method, molten metal is atomized by
using rare gas and sprayed, mixed with the reinforcements conveyed
by the rare gas at the other end, and deposited and cooled on a
platform to obtain composite parts. The injection molding method
applies a metal rapid solidification technology, and restrains
growth of grains and formation of segregation, so that the gains
are refined, and the reinforcements are distributed uniformly.
Metal atomization and hybrid deposition are two major influence
factors of the injection molding method; in the metal atomization
process, the parts often have higher porosity and shrinkage
phenomenon along with gas transfer; if solidification rate is too
fast after deposition, the reinforcements and the matrix are poor
in compound effect, or even are not compounded; if the
solidification rate is slow, the reinforcements can be distributed
unevenly, or even segregated; and the injection molding method, as
a novel composite preparation method, is high in cost, and
therefore, is not applicable for automatic batch production.
[0007] The in-situ composite method is a novel method for preparing
metal matrix composite; in this method, direct adding of the
reinforcements is not required, but the reinforcements are
generated in the melt by chemical reaction or other special
reactions; and nucleation and growth are both finished in the
matrix, and therefore, the phenomenon of incompatibility and poor
combination between reinforcements and matrix do not occur,
influence of wettability is avoided, resulting in the composite is
uniform and pure. The method is low in cost and simple in
technological process, and the obtained part is high in quality;
and however, the method for generating the reinforcements by
chemical reaction has limitations of less reinforcements, so the
requirements of batch production cannot be obtained.
[0008] In a powder metallurgy method, metal powder and
reinforcement powder are mixed by ball milling, and then formed by
hot-press sintering under the vacuum conditions. By using the
powder metallurgy method, matrix alloys do not need to be heated to
a molten state, so that the interface reaction between matrix and
reinforcements can be prevented; and after mixing, the
reinforcements are distributed in the matrix uniformly, and achieve
a favorable effect of strengthening. However, due to significant
difference in size, shape and performance 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 combination. In addition, the powder metallurgy method is not
applicable for larger structural materials, but applicable for
functional materials of small parts; the technological process of
the powder metallurgy method is relatively complicated, and high in
cost; and problems exist in a transportation process. Therefore,
the powder metallurgy method greatly restricts preparation and
production of the magnesium matrix composite as a structural
material.
[0009] For selection of the reinforcements, whether the wettability
between the reinforcements and the matrix is better or not, whether
the interface bonding strength is proper or not, and whether
chemical reaction occurs at the interfaces or not, need to be
noticed. At present, the reinforcements are approximately
classified into three categories: whiskers, fibers and particles,
such as lanthanum oxide particles, cerium oxide particles, silicon
carbide whiskers and carbon fibers, wherein, the fiber
reinforcements are high in cost, and can form strong textures, so
that the composite has poor performance, and the whiskers and
particles reinforced magnesium matrix composite have the advantages
of being easy to machine, stable in size, and the like. The rare
earth oxide particle reinforcements are high in melting point,
cannot be molten after being added to magnesium or magnesium alloy
solutions, and besides, cannot produce chemical reaction with the
matrix; if the reinforcements can exist in the matrix uniformly,
segregation of interstitial impurities at the grain boundary is
reduced, and the grain boundary strength can be improved; in
addition, rare earth oxides achieve the effect of pinning for
dislocation, and prevent dislocation from moving, so that the
strength of magnesium alloy is improved, and the plasticity cannot
be reduced greatly; and however, if the rare earth oxides are
directly added to the matrix melt, the particles can be
agglomerated due to poor wettability, and cannot be dispersed in
the matrix properly, so that the effect of dispersion strengthening
is not achieved.
SUMMARY OF THE INVENTION
[0010] The present invention aims to provide a preparation method
for a magnesium matrix composite. Reinforcements are dispersed with
salt flux, so that surface wettability is improved; then, the
reinforcements are added to a magnesium melt, so that the problem
of wettability between the reinforcements and a matrix is solved;
and the strength of the magnesium matrix composite is improved
while the process is simplified.
[0011] The preparation method comprises the following steps:
[0012] (1) Preparing magnesium ingots as raw materials; preparing
salt flux and reinforcements, wherein the salt flux is a mixture of
barium chloride, magnesium chloride, sodium chloride and calcium
chloride, the barium chloride accounts for 35-50% of a total mass
of the salt flux, the magnesium chloride accounts for 10-20% of a
total mass of the salt flux, the sodium chloride accounts for
10-20% of a total mass of the salt flux, a balance is the calcium
chloride and impurities, the impurities account for no more than 1%
of a total mass of the salt flux, the reinforcements are elementary
metal, rare earth oxides, carbides, borides or metal oxides, the
elementary metal is W, Mo or Ni, the rare earth oxides are
La.sub.2O.sub.3, CeO.sub.2 or Y.sub.2O.sub.3, the carbides are TiC
or SiC, the borides are ZrB.sub.2, the metal oxides are MgO or
SiO.sub.2, the reinforcements are 0.1-30% of a total volume of the
raw materials, and the reinforcements are 1-50% of a total volume
of the salt flux;
[0013] (2) Placing the salt flux in a clay crucible or a graphite
crucible, performing heating to 773K-923K to prepare salt flux
melts, placing the reinforcements in the salt flux melts, and
performing stirring until the reinforcements are uniformly
dispersed to prepare a liquid-solid mixture;
[0014] (3) Pouring the liquid-solid mixture into a
normal-temperature clay crucible or graphite crucible, and
performing cooling to normal temperature to obtain precursors;
[0015] (4) Preheating an iron crucible until a body of the iron
crucible is in a dark red heat, then placing the raw materials in
the iron crucible, and performing melting on the raw materials at
953K-1043K to form a raw material melt;
[0016] (5) Placing the precursors in the raw material melt of
953K-1043K, performing stirring until the precursors are dispersed
uniformly, under a condition of 953K-993K, adding refining agents,
performing stirring for refining, after the refining is finished,
controlling temperature to 1013K-1023K, and performing standing so
that impurity components are separated from composite components,
and scum and composite melt are obtained;
[0017] (6) Removing the scum from a surface of the composite melt,
then cooling the composite melt to 973K-982K, and performing
casting to form the magnesium matrix composite ingots.
[0018] A purity of the magnesium ingots is greater than or equal to
99.85%.
[0019] The reinforcements are fibers, particles or whiskers,
wherein a particle size of the particles is 300 nm-20 .mu.m; a
diameter of the whiskers is 0.1 .mu.m-1 .mu.m, and the length is 10
.mu.m-100 .mu.m; and a diameter of the fibers is 5 .mu.m-20 .mu.m,
and a continuous length is 10 mm-70 mm.
[0020] In the step (5), the precursors are crushed into particles
with the particle size of no more than 5 cm, and then the particles
are placed in the raw material melt.
[0021] In the step (2), a stirring rate is 100 r/min-200 r/min, and
a time is 2 min-10 min.
[0022] In the step (5), a stirring rate is 100 r/min-300 r/min, and
a time is 5 min-15 min.
[0023] In the step (2), when the reinforcements are added to the
salt flux melts, all the reinforcements are added in three to five
times, and the adding amount each time accounts for less than 50%
of the total mass of the reinforcements.
[0024] In the step (5), before refining, materials in the iron
crucible are degassed by using mixed gas, and the mixed gas is
formed by mixing components in percentage by volume of 0.2%-0.3% of
sulfur hexafluoride, 25%-50% of carbon dioxide and balance air.
[0025] In the step (5), a standing time is 10 min-30 min.
[0026] In the step (1), the magnesium ingots and other metal
components are prepared as the raw materials, when the step (4) is
performed, the magnesium ingots and the other metal components are
placed in the iron crucible jointly, melting is performed, and
stirring and uniform mixing are performed to form a raw material
melt, wherein the other metal components are one or more of
aluminum ingots, zinc ingots, manganese chloride, magnesium-rare
earth alloys, magnesium-zirconium alloys and magnesium-silicon
alloys, and aluminum, zinc, manganese, rare earth, zirconium and
silicon in the other metal components account for no more than 10%
of a total mass of the raw materials.
[0027] In the step (4), covering flux is scattered onto a surface
of the raw material melt so as to prevent magnesium from burning,
wherein the covering flux is No. 2 flux; when the step (5) is
performed, the covering flux is mixed with the scum; and when the
step (6) is performed, the covering flux and the scum are removed
together.
[0028] In the step (5), the refining agents are No. 2 flux.
[0029] Raw material components in the magnesium matrix composite
account for 80-99.9% of the total volume, and the components of the
reinforcements account for 0.1-20% of the total volume.
[0030] The preparation method is characterized in that the
reinforcements are put into molten salt flux, and uniformly
dispersed in molten salt by mechanical stirring; the surface
wettability of the reinforcements is improved by utilizing the high
wettability between the reinforcements and the molten salt; since
the difference between the density of barium chloride in the
selected molten salt and the density of magnesium melt is larger,
the reinforcements are separated from the molten salt after being
added to the magnesium melt; the wettability between the
reinforcements and the magnesium melt is high after surface
modification of the reinforcements, and the reinforcements can be
dispersed in the magnesium melt uniformly; the melt can be refined
by the used salt flux effectively, and impurities and a covering
melt are removed; and the magnesium is prevented from being
overburnt. The wettability of the reinforcements can be improved by
the barium chloride and other salts, so that the reinforcements are
easy to disperse in the matrix uniformly; the method provided by
the present invention is simple in process and low in cost, and the
strength of the magnesium matrix composite can be improved greatly;
and the method can be used for preparing bulk structural members of
the magnesium matrix composite, can be used for automatic
production, and is of great significance in development of
magnesium industry.
BRIEF DESCRIPTION OF DRAWINGS
[0031] FIG. 1 is an SEM diagram of a lanthanum oxide reinforced
magnesium matrix composite in the embodiment 1 of the present
invention; in the figure, (b) is the partial enlarged view of
(a);
[0032] FIG. 2 is an XRD diagram of the lanthanum oxide reinforced
magnesium matrix composite in the embodiment 1 of the present
invention; in the figure, (a) is the diffraction peaks of
La.sub.2O.sub.3, and (b) is the diffraction peaks of magnesium
matrix composite;
[0033] FIG. 3 is an SEM diagram of cerium dioxide reinforced
magnesium matrix composite in the embodiment 2 of the present
invention; in the figure, (b) is the partial enlarged view of
(a).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0034] A detailed description of the preparation method is given
below in combination with the embodiments of the present
invention.
[0035] In the embodiments of the present invention, temperature is
measured with a thermocouple to ensure the measurement accuracy of
the temperature.
[0036] The purity of an aluminum ingot and a zinc ingot in the
present invention is 98.9%-99.9%.
[0037] Manganese chloride in the present invention is technical
pure.
[0038] Magnesium-rare earth alloys, magnesium-zirconium alloys and
magnesium-silicon alloys in the present invention are collectively
referred to as master alloys, and rare earth, zirconium and silicon
in the master alloys account for 10%-40% of the total mass of the
master alloys separately.
[0039] The aluminum ingot, the reinforcements and No. 2 flux
adopted in the embodiments of the present invention are products
purchased on the market.
[0040] Barium chloride, magnesium chloride, sodium chloride and
calcium chloride adopted in the embodiments of the present
invention are industrial grade products purchased by
commercial.
[0041] An electron microscope adopted in the embodiments of the
present invention is Shimadzu SSX550.
[0042] X-ray diffraction observation equipment in the embodiments
of the present invention is PANalytical B. V. X pertpro.
[0043] The mass percentage of the reinforcements of the magnesium
matrix composite in the embodiments of the present invention is
analyzed and calculated by using an X-ray fluorescence spectrum,
and then converted into volume percentage.
[0044] The purity of the magnesium ingot in the embodiments of the
present invention is greater than or equal to 99.85%.
[0045] The reinforcements in the embodiments of the present
invention are fibers, particles or whiskers, wherein the particle
size of the particles is 300 nm-20 .mu.m; the diameter of the
whiskers is 0.1 .mu.m-1 .mu.m, and the length is 10 .mu.m-100
.mu.m; and the diameter of the fibers is 5 .mu.m-20 .mu.m, and the
continuous length is 10 mm-70 mm.
[0046] Before refining in the embodiments of the present invention,
materials in the iron crucible are degassed by using mixed gas, and
the mixed gas is formed by mixing components in percentage by
volume of 0.2%-0.3% of sulfur hexafluoride, 25%-50% of carbon
dioxide and balance air, and inflation time of the mixed gas is 2
min-5 min.
[0047] The adding quantity of refining agents in the embodiments of
the present invention is 0.5%-0.8% of the total mass of all melts
in the iron crucible.
Embodiment 1
[0048] A magnesium ingot is prepared as raw materials; salt flux
and reinforcements are prepared; the salt flux is a mixture of
barium chloride, magnesium chloride, sodium chloride and calcium
chloride, wherein the barium chloride accounts for 45% of the total
mass of the salt flux; the magnesium chloride accounts for 20% of
the total mass of the salt flux, and the sodium chloride accounts
for 15% of the total mass of the salt flux; the balance is the
calcium chloride and impurities, and the impurities account for no
more than 1% of the total mass of the salt flux; the reinforcements
are rare earth oxides, namely La.sub.2O.sub.3 particles; the
reinforcements account for 0.5% of the total volume of the raw
materials; the reinforcements account for 3% of the total volume of
the salt flux;
[0049] The salt flux is placed in a clay crucible, and heated to
803K to form salt flux melts; the reinforcements are added to the
salt flux melts, and uniformly dispersed by stirring to form a
liquid-solid mixture; the stirring rate is 100 r/min, and the
stirring time is 10 min; when the reinforcements are added to the
salt flux melts, all the reinforcements are added in three times,
and the adding amount each time accounts for less than 50% of the
total mass of the reinforcements;
[0050] The liquid-solid mixture is poured into the
normal-temperature clay crucible, and cooled to normal temperature
to obtain precursors;
[0051] An iron crucible is preheated until the body of the iron
crucible is in a dark red heat, then the raw materials are placed
in the iron crucible, and melting is performed on the raw materials
at 973K to form a raw material melt; the covering flux is scattered
onto the surface of the raw material melt, and used for preventing
the magnesium from burning, and the covering flux is the No. 2
flux;
[0052] Firstly, the precursors are crushed into particles with the
particle size of no more than 5 cm, then placed in the raw material
melt of 973K, and stirred until the precursors are dispersed
uniformly; next, refining agents are added at 973K, and stirred for
refining; the refining agents are the No. 2 flux, the stirring rate
is 100 r/min, the stirring time is 15 min, and the temperature
rises to 1013K after completion of refining; the precursors stand
so that impurity components are separated from composite components
to obtain scum and a composite melt; the standing time is 30
min;
[0053] The scum is removed from the surface of the composite melt,
and then the composite melt is cooled to 973K, and cast to form the
magnesium matrix composite; and the reinforcement components in the
magnesium matrix composite account for 0.41% of the total volume,
and the balance is the raw material components.
[0054] The SEM diagram of the magnesium matrix composite (lanthanum
oxide reinforced magnesium matrix composite) is shown as FIG. 1,
the XRD diagram is shown as FIG. 2, and as shown in the figures,
La.sub.2O.sub.3 phases are uniformly distributed in the matrix.
[0055] Under the same conditions, the quantity of the
reinforcements is regulated for parallel test, and the
reinforcements are respectively 1%, 3%, 5%, 7%, 9%, 15% and 20% of
the total volume of the raw materials; and in the lanthanum oxide
reinforced magnesium matrix composite which is formed finally,
80%-90% of the total mass of the reinforcements are reserved in the
matrix.
Embodiment 2
[0056] The method is the same as that in the embodiment 1, the
differences include:
[0057] (1) In salt flux, barium chloride accounts for 50% of the
total weight of the salt flux, magnesium chloride accounts for 10%
of the total weight of the salt flux, and sodium chloride accounts
for 20% of the total weight of the salt flux;
[0058] (2) Reinforcements are rare-earth oxides, namely CeO.sub.2
particles;
[0059] (3) The reinforcements are 1% of the total volume of raw
materials, and are 5% of the total volume of the salt flux;
[0060] (4) The salt flux is placed in a graphite crucible, and
heated to 773K to form salt flux melts; the stirring rate is 200
r/min, and the stirring time is 2 min; when the reinforcements are
added to the salt flux melts, all the reinforcements are added in
four times;
[0061] (5) A liquid-solid mixture is poured into the
normal-temperature graphite crucible;
[0062] (6) Raw materials in the iron crucible are molten at 953K to
form raw material melt;
[0063] (7) Precursors are placed in the raw material melt at 953K
after being crushed, refining agents are added at 953K, and stirred
for refining, the stirring rate is 300 r/min, the stirring time is
5 min, the temperature rises to 1023K after completion of refining,
and the standing time is 10 min;
[0064] (8) The composite melt is cooled to 982K, and cast to form
the magnesium matrix composite; and the reinforcement components in
the magnesium matrix composite account for 0.85% of the total
volume, and the balance is the raw material components.
[0065] The SEM diagram of the magnesium matrix composite (lanthanum
oxide reinforced magnesium matrix composite) is shown as FIG. 3,
and CeO.sub.2 phases are uniformly distributed in the matrix.
Embodiment 3
[0066] The method is the same as that in the embodiment 1, the
differences include:
[0067] (1) Magnesium ingots and other metal components are prepared
as the raw materials, wherein the other metal components are
aluminum ingots and account for 5% of the total mass of the raw
materials; in salt flux, barium chloride accounts for 35% of the
total weight of the salt flux, magnesium chloride accounts for 15%
of the total weight of the salt flux, and sodium chloride accounts
for 10% of the total weight of the salt flux;
[0068] (2) Reinforcements are borides namely ZrB.sub.2;
[0069] (3) The reinforcements are 10% of the total volume of raw
materials, and are 15% of the total volume of the salt flux;
[0070] (4) The salt flux is placed in a graphite crucible, and
heated to 883K to form salt flux melts; the stirring rate is 150
r/min, and the stirring time is 5 min; when the reinforcements are
added to the salt flux melts, all the reinforcements are added in
five times;
[0071] (5) A liquid-solid mixture is poured into the
normal-temperature graphite crucible;
[0072] (6) The magnesium ingots and other metal components are
placed in the iron crucible together, and the raw materials in the
iron crucible are molten at 1043K to form raw material melt;
[0073] (7) Precursors are placed in the raw material melt at 1043K
after being crushed, refining agents are added at 1043K, and
stirred for refining, the stirring rate is 200 r/min, the stirring
time is 10 min, the temperature is cooled to 1013K after completion
of refining, and the standing time is 20 min;
[0074] (8) The composite melt is cooled to 978K, and cast to form
the magnesium matrix composite; and the reinforcement components in
the magnesium matrix composite account for 8.1% of the total
volume, and the balance is the raw material components.
Embodiment 4
[0075] The method is the same as that in the embodiment 1, the
differences include:
[0076] (1) Magnesium ingots and other metal components are prepared
as the raw materials, wherein the other metal components are zinc
ingots and account for 2% of the total mass of the raw
materials;
[0077] (2) Reinforcements are elementary metal W;
[0078] (3) The reinforcements are 15% of the total volume of raw
materials, and are 25% of the total volume of the salt flux;
[0079] (4) The salt flux is placed in a graphite crucible, and
heated to 923K to form salt flux melts, the stirring rate is 120
r/min, and the stirring time is 8 min;
[0080] (5) A liquid-solid mixture is poured into the
normal-temperature graphite crucible;
[0081] (6) The magnesium ingots and other metal components are
placed in the iron crucible together, and the raw materials in the
iron crucible are molten at 1043K to form raw material melt;
[0082] (7) Precursors are placed in the raw material melt at 1043K
after being crushed, refining agents are added at 1043K, and
stirred for refining, the temperature is cooled to 1018K after
completion of refining, and the standing time is 15 min;
[0083] (8) The composite melt is cooled to 980K, and cast to form
the magnesium matrix composite; and the reinforcement components in
the magnesium matrix composite account for 13.3% of the total
volume, and the balance is the raw material components.
Embodiment 5
[0084] The method is the same as that in the embodiment 1, the
differences include:
[0085] (1) Magnesium ingots and other metal components are prepared
as the raw materials, wherein the other metal components are
magnesium-rare earth alloys and account for 4% of the total mass of
the raw materials; in salt flux, barium chloride accounts for 40%
of the total weight of the salt flux, magnesium chloride accounts
for 20% of the total weight of the salt flux, and sodium chloride
accounts for 20% of the total weight of the salt flux;
[0086] (2) Reinforcements are carbides namely TiC;
[0087] (3) The reinforcements are 22% of the total volume of raw
materials, and are 40% of the total volume of the salt flux;
[0088] (4) The salt flux is placed in a graphite crucible, and
heated to 828K to form salt flux melts; the stirring rate is 180
r/min, and the stirring time is 3 min; when the reinforcements are
added to the salt flux melts, all the reinforcements are added in
four times;
[0089] (5) A liquid-solid mixture is poured into the
normal-temperature graphite crucible;
[0090] (6) The magnesium ingots and other metal components are
placed in the iron crucible together, and the raw materials in the
iron crucible are molten at 988K to form raw material melt;
[0091] (7) Precursors are placed in the raw material melt at 988K
after being crushed, refining agents are added at 988K, and stirred
for refining, the stirring rate is 300 r/min, the stirring time is
5 min, the temperature rises to 1023K after completion of refining,
and the standing time is 25 min;
[0092] (8) The composite melt is cooled to 979K, and cast to form
the magnesium matrix composite; and the reinforcement components in
the magnesium matrix composite account for 18.6% of the total
volume, and the balance is the raw material components.
Embodiment 6
[0093] The method is the same as that in the embodiment 1, the
differences include:
[0094] (1) Magnesium ingots and other metal components are prepared
as the raw materials, wherein the other metal components are
magnesium-zirconium alloys and magnesium-silicon alloys, and
zirconium and silicon account for 10% of the total mass of the raw
materials; in salt flux, barium chloride accounts for 50% of the
total weight of the salt flux, magnesium chloride accounts for 10%
of the total weight of the salt flux, and sodium chloride accounts
for 10% of the total weight of the salt flux;
[0095] (2) Reinforcements are metal oxides namely SiO.sub.2;
[0096] (3) The reinforcements are 26% of the total volume of raw
materials, and are 45% of the total volume of the salt flux;
[0097] (4) Heating is performed to 873K to form salt flux melts,
the stirring rate is 160 r/min, the stirring time is 4 min, and
when the reinforcements are added to the salt flux melts, all the
reinforcements are added in five times;
[0098] (5) The magnesium ingots and other metal components are
placed in the iron crucible together, and the raw materials in the
iron crucible are molten at 993K to form raw material melt;
[0099] (6) Precursors are placed in the raw material melt at 993K
after being crushed, refining agents are added at 993K, and stirred
for refining, the stirring rate is 200 r/min, the stirring time is
10 min, the temperature rises to 1013K after completion of
refining, and the standing time is 25 min;
[0100] (7) The composite melt is cooled to 976K, and cast to form
the magnesium matrix composite; and the reinforcement components in
the magnesium matrix composite account for 21.1% of the total
volume, and the balance is the raw material components.
* * * * *