RU2539886C1 - Method for obtaining aluminium-phosphorus alloy combination - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method includes obtaining of aluminium-phosphorus ally in form of tablets of the following composition, wt %: phosphorus 1.5-3.5, iron 6.0-16, aluminium - balance. At that mixing of the aluminium granules and ferrophosphorus powder is performed in mill with rotation speed 60-250 rpm for 1-7 hours, and mixture components are cold pressed. The made tablets have diameter 20-100 mm, they are made by pressing with drying under force 100-5000 kg with free mixture filling on the hydraulic press.

EFFECT: invention decreases average size of the alloy particles, forms second phases, and uniformly distribute them over volume of the formed tablet.

6 cl, 2 dwg, 1 tbl, 3 ex

Description

The invention relates to ferrous metallurgy and can be used to produce aluminum-based alloys.

For the manufacture of castings with increased hardness and strength, maintaining dimensional stability during operation and having a high surface finish, alloys based on the Al-Si-Cu system are used. These alloys have a multiphase structure, which makes them highly susceptible to hot cracks. The main structural components of the alloys are primary crystals of the solid solution α _Al double eutectic α _Al + Si, triple eutectic α _Al + Si + CuAl ₂ , and in alloys with magnesium, the quadruple eutectic α _Al + Si + CuAl ₂ + Mg ₂ Si is released. During crystallization, silicon is released in the form of well-faceted large particles that have high hardness and brittleness, complicating the mechanical processing of castings and causing them to completely lose ductility. In order to give the desired properties to alloy products, the alloys are modified - crushed by macrograins, primary crystallizing phases and phases included in the eutectic, as well as by changing the shape of the release of brittle phases; aluminum alloys are modified, in particular, by phosphorus.

Phosphorus in aluminum alloys is introduced in the form of a mixture containing, for example, aluminum phosphate, potassium chloride, hexachloroethane and sulfur (RF patent No. 2287604, C22F 1/04, 11/20/2006), or in the form of Cu-P alloys obtained, for example, loading into the furnace a mixture consisting of a mixture of calcium oxide - phosphorus-containing materials, a reducing agent and copper, melting at a given temperature and releasing melting products from the furnace, metal silicon being used as a reducing agent, and charge components taken in an amount providing a ratio of P ₂ O ₅ : Si: Cu within 1: (0.4-1.0 ) :( 2.5-5.0), melted at 1623-1823K and the slag is separated from the ligature by separate discharge (RF patent No. 2171310, C22C 35/00, C22C 9/00, 07/27/2001).

There is also a method of producing aluminum-phosphorus alloys for modifying silumins, including mixing to obtain a uniform mixture of particles of ferrophosphorus and metallic aluminum and pressing it into molds (USSR Author's Certificate No. 1793742, C22C 1/06, 03/30/1994).

The disadvantages of this method include the high fineness of the particles in the ligature and, accordingly, their uneven distribution, which reduces the modifying ability of the ligature and leads to the formation of a triple intermediate phase β (AlFeSi), which crystallizes in the form of coarse needle-like precipitates, sharply reducing plastic properties alloys.

The objective of the invention is to increase the modifying properties of the ligature, obtaining alloys based on aluminum with desired properties at lower production costs and while improving the environmental characteristics of the process. The technical result is to reduce the average particle size in the ligature to 1.5-2.5 microns, the formation of the second phases and their uniform distribution over the volume of the molded tablet.

The technical result is achieved due to the fact that in the method of producing an aluminum-phosphorus ligature, comprising mixing aluminum granules and ferrophosphorus powder and compressing the mixture, mixing the components is carried out in a ball mill, and the mixture is cold pressed to obtain tablets of the composition, wt.%:

Phosphorus 1,5-3,5 Iron 6.0-16.0 Aluminum rest

Mixing the ligature components in a ball mill not only crushes the particles to the required size, which makes it possible to evenly distribute the particles over the volume of the tablets, but also form phases Al ₃ Fe, Fe ₂ P and FeAlP in the microstructure, which suppress the formation of the β phase themselves have a compact form. Cold pressing prevents recrystallization of the ligature, and its composition is optimal for producing, in particular, aluminum alloys of the grades AK6M2, AK12M2, A390 and many others. The density of the ligature is higher than the density of liquid aluminum and is 2.7-3.2 g / cm ³ .

The Fe ₂ P compound contained in the ligature has crystal lattice parameters (a = 0.5864 nm) close to silicon lattice parameters (a = 0.5431 nm). With the introduction of this ligature into the melt, additional crystallization centers of primary silicon appear in it in the form of finished Fe ₂ P particles grinding the structure.

Despite the fact that ferrophosphorus introduces an additional amount of iron, which is a harmful impurity for aluminum alloys, microstructural analysis of the samples showed that after processing the aluminum alloy with the stated ligature, iron intermetallides with aluminum and silicon in the form of needles are formed, however, the size of the needles of this phase in the structure of the sample is comparable with the size of eutectic silicon needles and even shorter than them, and the fraction of inclusions of the glandular phase with respect to the thin section is insignificant. In addition, the claimed ligature is used to obtain complex alloyed aluminum alloys, which include manganese, nickel, chromium, which change the morphology of the glandular phases and thereby reduce their negative effect on the properties of the alloys.

A method of obtaining a ligature can also be characterized by additional features that enhance the technical result. In particular, the mixing of the components is carried out at a rotational speed of the mill of 60-250 rpm./min; mixing of the components is carried out at a ratio of the masses of grinding media to the processed material from 5: 1 to 10: 1; grinding balls are steel balls with a diameter of 10-20 mm; the mixing time of the components is 1-7 hours; processing the mixture is carried out in an air atmosphere; from the obtained powder mixtures, tablets with a diameter of 20-100 mm are pressed with a force of 100-5000 kg with a free filling of the powder on a hydraulic press; the powder mixture additionally contains chips of ligature A1-10Fe.

The invention is illustrated by examples.

Example 1

Granular aluminum and ferrophosphorus powder were mixed in a ball mill. The ratio of the masses of grinding media to the processed material was taken 5: 1. The diameter of the steel balls is 15 mm. The mixing time was 7 hours. The rotation speed was 100 rpm. The composition of the processed material, wt.%:

Aluminum (granules) 90 Ferrophosphorus (powder) 10

After processing the material in a ball mill, the mixture was pressed with a force of 300 kg.

When performing the above example, get 2% ligature A1-P with the extraction of the latter 97%.

 Example 2

In a ball mill, granular aluminum, A1-10Fe ligature chips and ferrophosphorus powder were mixed. The ratio of the masses of grinding media to the processed material was taken 7: 1. The diameter of the steel balls is 15 mm. The mixing time was 5 hours. The rotation speed was 150 rpm. The composition of the processed material, wt.%:

Aluminum (granules) 60 Ligature A1-10Fe thirty Ferrophosphorus (powder) 10

After processing the material in a ball mill, the mixture was pressed with a force of 1000 kg.

When performing the above example, get 2% ligature A1-P with the extraction of the latter 95%.

 Example 3

Granular aluminum and ferrophosphorus powder were mixed in a ball mill. The ratio of the masses of grinding media to the processed material was taken 10: 1. The diameter of the steel balls is 15 mm. The mixing time was 3.5 hours. The rotation speed was 250 rpm. The composition of the processed material, wt.%:

Aluminum (granules)  90 Ferrophosphorus (powder)  10

After processing the material in a ball mill, the mixture was pressed with a force of 3000 kg.

When performing the above example, get 2% ligature A1-P with the extraction of the latter 99.8%.

The resulting ligature was used for the production of aluminum alloys of the following grades.

Table 1 Brand designation Mass fraction of elements,% Al Si Fe Cu Mn Mg Ti Ni Pb Sn Zn P Other elemen AK6M2 89.8-92.3 5.5-6.5 up to 0.6 1.8-2.3 up to 0.1 0.3-0.45 0.1-0.2 up to 0.05 - - up to 0.06 0.001 0.7 AK12M2 81.6-86.6 11-13 0.6-1 1.8-2.5 up to 0.5 up to 0.2 up to 0.2 up to 0.3 up to 0.15 up to 0.1 up to 0.8 0.001 2.2 A390 75-77 16-18 up to 0.3 4-5 - 0.6 - - - - 0.01 1,0

The modifying ability of the resulting ligatures was tested on A1-17SL alloy. Phosphorus was added to silumin in an amount of 0.008%. In the cast structure of the unmodified alloy A1-17Si (Fig. 1a), the primary silicon crystals are coarse, unevenly distributed in the thin section plane. The shape of the crystals varies from fairly equiaxed faceted to lamellar, with an average size of about 50 microns (maximum - 120 microns). With the introduction of phosphorus by the Al-8Fe-2P alloy in an amount of 0.008%, a significant modification effect is already observed (Fig. 1b). Primary silicon crystals are uniformly distributed in the thin section plane in the form of equiaxed faceted crystals with an average size of 15 μm (maximum - 30 μm).

Claims (6)

1. The method of obtaining the ligature aluminum-phosphorus in the form of tablets of the composition, wt. %: phosphorus 1.5-3.5, iron 6.0-16, aluminum the rest, characterized in that the components are mixed in the form of aluminum granules and ferrophosphorus powder in a ball mill with a mill rotation speed of 60-250 rpm for 1-7 hours and cold pressing the treated mixture. 2. The method according to claim 1, characterized in that the mixing of the components is carried out at a mass ratio of the grinding media and the processed mixture from 5: 1 to 10: 1. 3. The method according to claim 1, characterized in that the grinding bodies are steel balls with a diameter of 10-20 mm 4. The method according to claim 1, characterized in that the processing of the mixture is carried out in an air atmosphere. 5. The method according to claim 1, characterized in that the tablets are obtained with a diameter of 20-100 mm by pressing with a force of 100-5000 kg with free filling of the mixture on a hydraulic press. 6. The method according to claim 1, characterized in that the ligature chips A1-10Fe are additionally introduced into the processed mixture.

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