CN111455279A

CN111455279A - Iron-aluminum alloy and preparation method thereof

Info

Publication number: CN111455279A
Application number: CN202010131434.0A
Authority: CN
Inventors: 陈学敏; 达克沃斯·罗纳德·雷; 余跃明; 王庆超; 周志
Original assignee: Shenzhen Sunxing Light Alloy Materials Co Ltd
Current assignee: Shenzhen Sunxing Light Alloy Materials Co Ltd
Priority date: 2020-02-28
Filing date: 2020-02-28
Publication date: 2020-07-28
Also published as: US20230100820A1; WO2021169074A1

Abstract

The invention discloses an iron-aluminum alloy and a preparation method thereof, wherein the iron-aluminum alloy accounts for 50-80% by weight of iron, and the balance is aluminum. The method comprises the following steps: adding metal aluminum or aluminum liquid into a container, wherein the temperature of the aluminum liquid is 700-; adding a metallic iron raw material into molten aluminum, adding a furnace cover, measuring pressure, introducing argon gas to enable the interior of the magnetic induction furnace to be in a positive pressure state, and stirring by using a graphite stirring head; electrifying, heating and raising the temperature to raise the temperature of the metal aluminum or the aluminum liquid to over 1000 ℃, melting, and keeping the temperature between 1000 and 1500 ℃; after alloying, cooling to about 1000 ℃, opening a furnace cover, and taking out the iron-aluminum alloy. Compared with the existing products, the iron and the aluminum in the iron-aluminum alloy prepared by the invention are fully alloyed, so that the absorption rate of iron as an alloy addition element in molten aluminum in the aluminum processing and smelting process and the physical properties of the processed aluminum are improved, and the environmental pollution in the production process is reduced.

Description

Iron-aluminum alloy and preparation method thereof

Technical Field

The invention relates to the technical field of iron-aluminum alloy and preparation thereof, in particular to iron-aluminum alloy and a preparation method thereof.

Background

In the production process of aluminum alloy materials (such as aluminum plates for aviation, pot, PS plate base and the like), it is usually necessary to add metallic iron element into molten aluminum melt (the temperature is generally controlled between 740-750 ℃) so that the metallic iron and aluminum form an aluminum-iron alloy intermetallic compound with a dense chain-shaped network structure to significantly improve the physical properties of the aluminum material. However, since the melting point of metallic iron is 1538 ℃ and the temperature of the melting process of aluminum melt is generally controlled between 740 ℃ and 750 ℃, in order to quickly dissolve metallic iron into the aluminum melt and form intermetallic compounds (intermetallic compounds of aluminum and iron) with aluminum, the following methods are mainly used at present:

the first way is to add a calculated amount of iron additive to the aluminium melt, which is composed of a certain mesh of iron powder and mechanically crushed potassium fluoroaluminate (KAlF)₄PAF is commonly called as a raw material, the raw material is uniformly mixed by a physical method and then is pressed into cakes by a mechanical pressure (oil pressure, air pressure and the like), the cakes are put into molten metal aluminum because the specific gravity of the cakes is greater than that of the molten metal aluminum, and metallic iron can be quickly dissolved into the molten metal and form intermetallic compounds (alloy) with aluminum due to the fluxing action of the PAF, but the main component of the PAF contains fluorine element (F), so that the environmental pollution is caused due to the volatilization and cleaning (refining) of the fluorine element (F) in the production process.

The second way is to mix the fluxing agent potassium fluoroaluminate (KAlF)₄Commonly known as PAF) to be replaced by aluminum powder, because the aluminum powder can be combusted at 740 ℃ to generate aluminum oxide and synchronously generate a large amount of heat energy, the heat energy generated during the combustion of the aluminum powder can promote the iron powder to be rapidly melted into the aluminum melt, and make the metallic iron and the aluminum melted into the aluminum melt form an alloy (intermetallic compound), but because the combustion heat of the aluminum powder is released in the whole process and then the aluminum powder is completely oxidized into the aluminum oxide, the aluminum oxide can partially enter the molten aluminum liquid, a negative effect is formed on the purification of the aluminum melt, and simultaneously because the cost of the aluminum powder is higher,the alumina after complete combustion can only become slag in the smelting process to be removed, and the production cost is increased.

In order to solve the technical problems, at present, a calculated amount of iron element additive, commonly called iron agent, is usually added into a molten aluminum liquid at 740-. The common specifications of the currently popular iron agents include 70 iron agents (iron content 70%, weight ratio), 75 iron agents (iron content 75%, weight ratio), 80 iron agents (iron content 80%, weight ratio), 85 iron agents (iron content 85%, weight ratio) and the like, and the iron agents are usually produced by the following two methods:

1. iron powder with a certain mesh number and potassium fluoroaluminate (commonly called PAF) powder with a certain mesh number are uniformly mixed and pressed into a cake shape by a mechanical mode through pressure and a mould in a combined mode, and the specific gravity of the cake shape is larger than that of an aluminum melt, so that the cake shape can be ensured to be sunk into the aluminum melt in the adding process, and the cake shape is prevented from being oxidized by air as much as possible.

2. The aluminum powder with a certain mesh number and the iron powder with a certain mesh number are uniformly mixed, and then the mixture is pressed into a cake-shaped object through a mechanical mode through pressure and a mould, wherein the specific gravity of the cake-shaped object is larger than that of the aluminum melt, so that the cake-shaped object can be ensured to be immersed into the aluminum melt in the adding process and is prevented from being oxidized by air as much as possible, wherein the iron powder accounts for 70% or 75%, 80%, 85% and the like by weight, and the aluminum powder accounts for 30%, 25%, 20% and 15% by weight. Also commonly referred to commercially as 70 iron, 75 iron, 80 iron, 85 iron, and the like.

The production mode of the two iron agents comprises the physical mixture of iron and aluminum or iron and PAF, when the physical mixture is used as an additive of an iron element and added into molten aluminum liquid, the strength of the produced aluminum material is increased by two steps to completely form an intermetallic compound (aluminum-iron alloy), and the first step is the dissolving process of the element iron in the molten aluminum liquid; the second step is a process of alloying (forming intermetallic compound) the metallic iron and the aluminum which are dissolved into the aluminum liquid; the two processes are completed with the following defects:

1. in the process, the element iron can be oxidized by oxygen in the air to form iron oxide which floats on the surface of the molten aluminum to influence the absorption rate of the metal iron in the smelting process;

2. the process that the metallic iron and aluminum which are successfully dissolved into the aluminum liquid form intermetallic compounds and are textured into dense reticular strengthening phases needs time, and the integrity of the process can influence the strength and quality of the aluminum material due to improper time control or insufficient time control of the smelting process.

Disclosure of Invention

The invention mainly aims to provide an iron-aluminum alloy and a preparation method thereof, aiming at realizing the first full alloying of iron and aluminum in the iron-aluminum alloy, then using the iron-aluminum alloy as an iron element additive to replace the current popular iron agent, and adding the iron element additive into molten aluminum liquid in the smelting process.

In order to achieve the purpose, the invention provides an iron-aluminum alloy which is composed of metal iron and aluminum, wherein the iron-aluminum alloy comprises 50-80% of iron by weight percent, and the balance of aluminum.

The iron-aluminum alloy is an intermetallic compound formed by metallic iron and metallic aluminum in a high-temperature state.

The iron-aluminum alloy can be in the shape of blocks, sheets and powder with indefinite shapes, and the specification of the iron-aluminum alloy can be limited by setting corresponding standards no matter the iron-aluminum alloy is in the shape of blocks, sheets and powder.

In order to achieve the above object, the present invention further provides a method for preparing an iron-aluminum alloy, comprising the following steps:

step S1, adding metal aluminum or aluminum liquid into a container, wherein the temperature of the aluminum liquid is 700-800 ℃;

step S2, adding metallic iron raw materials (iron sheets, iron powder, iron blocks, scrap iron or one or a plurality of mixtures thereof) into the molten aluminum, adding a furnace cover, vacuumizing, introducing argon, measuring temperature and pressure to enable the interior of the magnetic induction furnace to be in a positive pressure state, and stirring by using a graphite stirring head;

step S3, electrifying, heating and raising the temperature to raise the temperature of the metal aluminum or the aluminum liquid to more than 1000 ℃, melting, and keeping the temperature between 1000 and 1500 ℃, wherein the metal aluminum and the iron form intermetallic compounds in the process, and the time required by the alloying process is between 30 minutes and 2 hours;

and step S4, cooling to about 1000 ℃ after alloying is finished, opening a furnace cover, and taking out the iron-aluminum alloy.

The further technical proposal of the invention is that the container is a crucible arranged in a vacuum magnetic induction electric furnace, or a crucible arranged in a vacuum resistance furnace, or a non-vacuum container added with protective flux.

The further technical scheme is that the frequency of the induction furnace is 800-1200 HZ.

The further technical scheme of the invention is that the metallic iron raw material is iron sheet, iron powder, iron block, iron filings or one or more of the mixture of the iron sheet, the iron powder, the iron block and the iron filings.

The further technical scheme of the invention is that in the step S3, the stirring time is 0.5-2 hours by using a graphite stirring head.

The further technical scheme of the invention is that the production method of the iron-aluminum alloy comprises but is not limited to the production by using a vacuum magnetic induction furnace, also can use a crucible which is lined with different materials by a vacuum resistance furnace, and also can use other heating methods which select proper protective flux and fluxing agent to isolate air by using a non-vacuum method.

A further technical solution of the present invention is that, after the step S4, the method further includes:

the iron-aluminum alloy is poured into various types of blocks, sheets or powder with different diameters according to the specified requirements, and is used as an iron element additive to be added into the melting preparation process of an aluminum alloy material so as to change the physical properties of the processed aluminum material.

The iron-aluminum alloy and the preparation method thereof have the beneficial effects that:

compared with the existing product, the iron and the aluminum in the iron-aluminum alloy prepared by the invention are fully and completely alloyed, the fully alloyed iron-aluminum alloy is not a physical mixture of aluminum powder and iron powder, nor a physical mixture of iron powder and potassium fluoroaluminate (commonly called PAF) as compared with the existing iron additive used for producing aluminum materials to increase the strength of the aluminum materials, and the iron-aluminum alloy as an element additive of metallic iron in the production process of the aluminum materials replaces the existing popular iron additive (one is a cake-shaped substance formed by pressing the metallic iron powder and the potassium fluoroaluminate powder in a pressure mode after being physically and uniformly mixed according to a certain proportion, and the other is a cake-shaped substance formed by pressing the metallic iron powder and the metallic aluminum powder in a pressure mode after being physically mixed) and has the following four major advantages:

1. the problem of environmental pollution (fluorine pollution) caused by the fact that potassium fluoroaluminate as a fluxing agent for metal iron enters an aluminum melt and forms an intermetallic compound with metal aluminum after the smelting and dissolving process is finished is solved;

2. the problem of pollution (aluminum oxide inclusion) to the aluminum alloy melt after smelting and dissolving of aluminum powder serving as a heating agent for forming intermetallic compounds between the aluminum melt and the metal aluminum (alloying of the molten iron is assisted by high heat generated in the oxidation process of the aluminum powder) is solved;

3. the iron-aluminum alloy is used as an iron element additive which basically forms intermetallic compounds, and the iron-aluminum alloy plays a role in forming a diffusion and dense net-shaped alloying intermetallic compound in an aluminum melt after being added into the aluminum melt instead of forming the intermetallic compound and then performing diffusion net-forming, so that the strength quality and the purity of the produced aluminum material are far higher than those of the aluminum material produced by the first and second iron additives by using the iron-aluminum alloy as the iron element additive in the same iron agent adding smelting time;

4. compared with iron additives (pressure processed physical mixture formed by iron powder and PAF, and iron powder and aluminum powder), the iron-aluminum alloy has better absolute absorption rate of metallic iron and physical properties of processed aluminum material in the aluminum smelting and adding process.

Drawings

FIG. 1 is a diffractogram of AlFe 50;

FIG. 2 is a diffractogram of AlFe 55;

FIG. 3 is a diffractogram of AlFe 60;

FIG. 4 is a diffractogram of AlFe 70;

FIG. 5 is a gold phase diagram of AlFe 20;

FIG. 6 is a gold phase diagram of AlFe 50;

FIG. 7 is a gold phase diagram of AlFe 55;

FIG. 8 is a gold phase diagram of AlFe 60;

FIG. 9 is a gold phase diagram of AlFe 70;

FIG. 10 is a gold phase diagram of AlFe 80;

FIG. 11 is a gold phase diagram of AlFe20, aluminum liquid at 750 ℃, Fe 1% content controlled, 100 times, 200 times and 500 times of aluminum alloy after 60 minutes of absorption;

FIG. 12 is a diagram of the gold phase of 100 times, 200 times and 500 times of aluminum alloy after absorption for 60 minutes by AlFe50, aluminum liquid at 750 ℃, Fe 1% content control;

FIG. 13 is a gold phase diagram of AlFe55, aluminum liquid at 750 ℃, Fe 1% content controlled, 100 times, 200 times and 500 times of aluminum alloy after 60 minutes of absorption;

FIG. 14 is a gold phase diagram of AlFe60, aluminum liquid at 750 ℃, Fe 1% content controlled, 100 times, 200 times and 500 times of aluminum alloy after 60 minutes of absorption;

FIG. 15 is a diagram of gold phases of 100 times, 200 times and 500 times of aluminum alloy after absorption for 60 minutes by AlFe70, aluminum liquid at 750 ℃, Fe 1% content control;

FIG. 16 is a diagram of a 100-fold, 200-fold and 500-fold gold phase of an aluminum alloy after absorption for 60 minutes by using an iron agent (AlFe80), a 750 ℃ molten aluminum and controlling the content of Fe 1%;

FIG. 17 is a schematic flow chart of a preferred embodiment of the method for producing an iron-aluminum alloy according to the present invention;

fig. 18 is a schematic view of the structure of the magnetic induction electric furnace.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In order to realize the full alloying of iron and aluminum in the iron-aluminum alloy, improve the absorption rate and absorption speed of iron in the iron-aluminum alloy additive in the processing process of an iron-aluminum alloy section bar and reduce the environmental pollution, the invention provides the iron-aluminum alloy, which consists of 50-80% of iron and the balance of aluminum in percentage by weight.

The weight percentage of the iron may be, for example, 50%, 55%, 60%, 70%, 80%, and the corresponding iron-aluminum alloy may be expressed as AlFe50, AlFe55, AlFe60, AlFe70, and AlFe 80.

It can be understood that the iron-aluminum alloy provided by the invention is mainly used as an additive of elemental iron in the production process of aluminum alloy profiles. It is to be noted that the iron-aluminum alloy product should be limited in its impurities, such as iron and silicon contents should not be greater than 0.5%, and the combined amount of aluminum oxide and iron oxide should not be greater than 0.5%.

In this embodiment, the metallic iron and the metallic aluminum generate intermetallic compounds AlFe3, Al5Fe2, AlFe and Fe elementary substances when melted at a high temperature, wherein the iron-aluminum phase diagram refers to fig. 1 to 4.

FIG. 1 is a diffractogram of AlFe 50;

FIG. 2 is a diffractogram of AlFe 55;

FIG. 3 is a diffractogram of AlFe 60;

fig. 4 is a diffraction pattern of AlFe 70.

In this example, the phase diagrams of various AlFe alloys are shown in FIGS. 5 to 10.

FIG. 5 is a gold phase diagram of AlFe 20;

FIG. 6 is a gold phase diagram of AlFe 50;

FIG. 7 is a gold phase diagram of AlFe 55;

FIG. 8 is a gold phase diagram of AlFe 60;

FIG. 9 is a gold phase diagram of AlFe 70;

FIG. 10 is a gold phase diagram of AlFe 80.

In this example, the phase diagram of the alloy of the aluminum alloy after absorbing the alloy of different kinds of AlFe alloy and the corresponding physical property index are shown in fig. 11 to 16.

FIG. 16 is a gold phase diagram of 100 times, 200 times and 500 times of aluminum alloy after absorbing for 60 minutes by using an iron agent (AlFe80), aluminum liquid at 750 ℃, and the content of Fe 1% controlled.

With reference to fig. 11 to 16, the aluminum alloy material formed after the 80 iron agent is dissolved in the aluminum liquid at 750 ℃ for 1 hour can be seen from the phase diagram:

1. a small amount of incompletely alloyed elemental iron particles is present;

2. the 80 iron agent has obvious difference in the distribution, arrangement and shape of the aluminum iron compound phase compared with various aluminum iron alloys (20, 50, 55, 60, 70, 80) observed under a microscope of 500 times.

The service performance of 80 iron agent and various aluminum-iron alloys (20, 50, 55, 60, 70, 80) is shown in table 1.

TABLE 1

As can be seen from Table 1, the service performance (influence on physical properties of the processed aluminum material) of the aluminum-iron 20 is substantially the same as that of the 80-iron agent, and the physical property indexes of the aluminum-iron 60 are all changed remarkably.

In comparison with fig. 12, 13, 14 and 15, in fig. 11, it can be seen from the phase diagrams that the arrangement of the aluminum-iron alloy compound phase of the AlFe20 is obviously inferior to that of the alloy phases of AlFe50, AlFe60, AlFe65 and AlFe70, and the alloy phases of AlFe50, AlFe60, AlFe65 and AlFe70 are more compact, so that the processed aluminum alloy material has better physical properties.

Fig. 16 can be seen in comparison with fig. 12, 13, 14, 15: 1. in fig. 16 there is a small amount of incompletely alloyed elemental iron particles present; 2. in fig. 16, the distribution and arrangement of the phase of the aluminum-iron compound and the shape of the phase of the aluminum-iron compound are observed under a 500-fold microscope to be obviously different from those of various aluminum-iron alloys (20, 50, 55, 60, 70 and 80).

Compared with the currently popular iron element additive, the iron-aluminum alloy provided by the invention has the advantages that the absolute absorption rate and the physical properties of iron are obviously changed in the aluminum alloy material smelting process, particularly the physical properties of the corresponding aluminum material are particularly outstanding after the iron element of the iron-aluminum alloy is absorbed by the aluminum alloy, namely AlFe 60.

In order to achieve the purpose, the invention also provides a preparation method of the iron-aluminum alloy.

Referring to fig. 14, fig. 14 is a schematic flow chart of a preferred embodiment of a method for preparing an iron-aluminum alloy according to the present invention.

As shown in fig. 14, in this embodiment, the preparation method of the iron-aluminum alloy includes the following steps:

step S1, adding metal aluminum or aluminum liquid into the container, wherein the temperature of the aluminum liquid is 700-800 ℃.

The container may be a crucible 3 placed in a magnetic induction furnace as shown in FIG. 9. The magnetic induction electric furnace comprises a furnace cover 1, a magnetic induction electric furnace shell 2, a vacuumizing hole 5, a pressure measuring hole 6, an argon introducing hole 7 and a temperature measuring hole 8, wherein the magnetic induction electric furnace shell 2 is made of aluminum material, a copper magnetic induction coil 4 (hollow and cooling water introduced into the crucible) is arranged on the periphery of a crucible 3 arranged in the magnetic induction electric furnace, and the crucible 3 can be a silicon carbide crucible, a graphite crucible, a clay crucible or other refractory materials, such as: the crucible for containing the metal furnace liquid for the induction furnace is formed by hammering the ramming materials such as quartz sand, magnesium oxide, aluminum oxide and the like.

Wherein, the frequency of the magnetic induction furnace can be 800-1200 Hz.

In other embodiments, the container may be a vacuum resistance furnace lined with crucibles of different materials, or other heating methods without vacuum, with the flux being suitably protected from air.

And step S2, adding the metallic iron raw material into the molten aluminum liquid at 700 ℃, adding a furnace cover, vacuumizing, introducing argon, measuring temperature and pressure to enable the interior of the induction furnace to be in a positive pressure state, and stirring by using a graphite stirring head.

And step S3, electrifying, heating and raising the temperature to raise the temperature of the metal aluminum or the aluminum liquid to more than 1000 ℃, melting, and keeping the temperature between 1000 and 1500 ℃, such as 1000 ℃, or 1250 ℃, or 1500 ℃, wherein the metal aluminum and the iron form intermetallic compounds in the process to obtain the iron-aluminum alloy, and the time required by the alloying process is between 30 minutes and 2 hours.

Wherein, the metallic iron raw material can be iron powder, scrap iron, iron blocks, iron sheets or a mixture of one or more of the iron powder, the scrap iron, the iron blocks and the iron sheets.

In this embodiment, the stirring time of the stirring with the graphite stirring head may be set to 0.5 to 2 hours, for example, 0.5 hour, 1.25 hours, or 2 hours, according to actual requirements.

It will be appreciated that the time requirement for the entire alloying process is generally controlled to be in the range of 30 minutes to 2 hours, which ensures that the metallic iron and aluminium form intermetallic compounds as much as possible, thereby obtaining an acceptable fully alloyed iron-aluminium alloy, avoiding the formation of small amounts of metal oxides (iron oxide or aluminium oxide).

Furthermore, as an embodiment, the step S4 may be followed by:

pouring the iron-aluminum alloy into an amorphous block shape or a sheet shape, or processing the iron-aluminum alloy into a powder shape in a mechanical crushing mode, and accurately adding the iron-aluminum alloy as an iron element additive into the smelting preparation process of the aluminum alloy material in a calculation mode. The iron-aluminum alloy can be in the shape of blocks, sheets and powder with indefinite shapes, and the specification of the iron-aluminum alloy can be limited by setting corresponding standards no matter the iron-aluminum alloy is in the shape of blocks, sheets and powder.

The iron-aluminum alloy and the preparation method thereof have the beneficial effects that: compared with the existing product, the iron and the aluminum in the iron-aluminum alloy prepared by the invention are fully and completely alloyed, the fully alloyed iron-aluminum alloy is not a physical mixture of aluminum powder and iron powder, nor a physical mixture of iron powder and potassium fluoroaluminate (commonly called PAF) as compared with the existing iron additive used for producing aluminum materials to increase the strength of the aluminum materials, and the iron-aluminum alloy as an element additive of metallic iron in the production process of the aluminum materials replaces the existing popular iron additive (one is a cake-shaped substance formed by pressing the metallic iron powder and the potassium fluoroaluminate powder in a pressure mode after being physically and uniformly mixed according to a certain proportion, and the other is a cake-shaped substance formed by pressing the metallic iron powder and the metallic aluminum powder in a pressure mode after being physically mixed) and has the following four major advantages:

4. the iron-aluminum alloy has better absolute absorption rate and absorption speed of metallic iron in the aluminum smelting and adding process compared with iron additive (pressure-processed physical mixture formed by iron powder and PAF, and iron powder and aluminum powder).

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. The iron-aluminum alloy is characterized by comprising metal aluminum and iron, wherein the iron-aluminum alloy comprises 50-80% of iron by weight and the balance of aluminum.

2. A method of producing an iron-aluminium alloy according to claim 1, characterised in that it comprises the steps of:

step S2, adding a metallic iron raw material into molten aluminum liquid, adding a furnace cover, vacuumizing, introducing argon, measuring temperature and pressure to enable the interior of the magnetic induction furnace to be in a positive pressure state, and stirring by using a graphite stirring head;

3. The method for producing an iron-aluminum alloy according to claim 2, wherein the vessel is a crucible placed in a magnetic induction furnace, or a crucible placed in a vacuum resistance furnace, or a non-vacuum heatable vessel to which a protective flux and a flux are added.

4. The method for preparing an iron-aluminum alloy according to claim 3, wherein the frequency of the induction furnace is 800 to 1200 HZ.

5. The method of claim 2, wherein the metallic iron raw material is iron powder, iron flakes, iron filings or iron blocks, or a mixture of one or more types thereof.

6. The method according to claim 2, wherein in step S3, the stirring time with the graphite stirring head is 0.5-2 hours.

7. The method according to any one of claims 2 to 7, wherein the step S4 is further followed by:

the iron-aluminum alloy is poured into various types of blocks and sheets, or is crushed into particles (including powder) with different diameters according to the specified requirements, and the iron-aluminum alloy is used as an iron element additive to be added into the smelting preparation process of an aluminum alloy material so as to change the physical properties of the manufactured aluminum material.