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.

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 9835K, 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 m; the whisker has a diameter of 0.1-1 m and a length of 10-100 m; and the fibers have a diameter of 5-20 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

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 m; the whisker has a diameter of 0.1-1 m and a length of 10-100 m; and the fibers have a diameter of 5-20 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 9835K, 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.