CN109913675B

CN109913675B - Al-B-P dual modifier for eutectic aluminum-silicon alloy and preparation method and application thereof

Info

Publication number: CN109913675B
Application number: CN201910225558.2A
Authority: CN
Inventors: 王建华; 王硕; 刘亚; 涂浩; 苏旭平
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2019-03-25
Filing date: 2019-03-25
Publication date: 2020-10-09
Anticipated expiration: 2039-03-25
Also published as: CN109913675A

Abstract

The invention belongs to the field of processing and preparation of non-ferrous alloys, and relates to an Al-B-P dual modifier for eutectic aluminum-silicon alloy, and preparation and application thereof. α -Al + AlB exist according to an isothermal cross-section phase relation of an Al-B-P ternary system at 700 DEG C₂And the AlP three-phase region is designed with an Al-B-P intermediate alloy. The alloy comprises the following components in percentage by mass: 0.5 to 15.0 percent of B, 0.5 to 15.0 percent of P and the balance of Al. Uniformly mixing aluminum powder, boron powder and red phosphorus powder with the particle size of 80-150 meshes, then flatly paving the mixture on a steel plate, putting the steel plate into a steel box, sealing and vacuumizing the steel box, and then carrying out in-situ reaction in a furnace at the temperature of 840-930 ℃ to prepare the Al-B-P composite modifier. The Al-B-P dual alterant prepared by the invention is used for the modification treatment of the eutectic aluminum-silicon alloy, and can obviously improve the microstructure and the mechanical property of the eutectic aluminum-silicon alloy.

Description

Al-B-P dual modifier for eutectic aluminum-silicon alloy and preparation method and application thereof

Technical Field

The invention belongs to the field of processing and preparation of nonferrous metals, and relates to an Al-B-P dual alterant for eutectic aluminum-silicon alloy, a preparation method and application thereof.

Background

The cast aluminum-silicon alloy has the advantages of low density, small thermal expansion coefficient, high specific strength and the like, is the alloy with the widest application range and the largest yield in the cast aluminum alloy, accounts for more than 80 percent of the total amount of the cast aluminum alloy, and is widely applied to the fields of automobiles, aerospace and aviation, particularly cylinders and pistons. Under the conventional casting conditions, the aluminum-silicon alloy has the following problems: 1) the grain structure of the aluminum matrix is relatively coarse; 2) the thick needle sheet-shaped eutectic silicon severely cracks the substrate; 3) as the content of silicon increases, coarse and irregular blocky primary crystal silicon appears in the aluminum-silicon alloy structure, and the toughness of the alloy is obviously reduced. Modification is the most conventional means for regulating the structure of the aluminum-silicon alloy, and aims to improve the comprehensive mechanical property of the alloy finally by refining an aluminum phase and a silicon phase or improving the form of the silicon phase.

The eutectic silicon is modified by Na, Sr, Ca, Ba, RE and the like, and can change eutectic Si from a needle sheet shape into a fiber shape. The deterioration mechanism is an impurity-promoted twin mechanism (IIT), which is based on a twin valley mechanism (TPRE). Elements for modifying the aluminum matrix include Ti, B, Zr, etc., and TiAl compounds thereof₃，AlB₂，TiB₂，TiC，ZrAl₃The Al has similar crystal structure and lattice constant, and can be used as heterogeneous nucleation core of Al, thereby refining Al grains. The metamorphic element of primary crystal Si is mainly P, Al reacts with P to generate AlP compound which is dispersed in alloy melt, the crystal structure of the AlP compound is the same as that of Si, the AlP compound belongs to face-centered cubic lattice, the lattice constants of the AlP compound are similar, the AlP compound is used as a heterogeneous nucleation core of the primary crystal Si, and therefore the primary crystal silicon is refined, and meanwhile, the growth of eutectic Si can be indirectly inhibited by adding P.

Disclosure of Invention

The Al-3B and Al-3P alloys are adopted to carry out composite modification treatment on the aluminum-silicon alloy, so that the toughness of the aluminum-silicon alloy can be obviously improved, but the Al-3B and Al-3P alloys need to be respectively prepared and the composite modification treatment is carried out step by step, and the modification process is relatively complex. The invention aims to design and develop an Al-B-P composite modifier for modification treatment of eutectic aluminum-silicon alloy, and simplify the composite modification process of the eutectic aluminum-silicon alloy.

The invention is realized by the following method, and the specific operation steps comprise:

(1) according to mass percent, boron: 0.5 to 15.0 percent; phosphorus: 0.5 to 15.0 percent; weighing aluminum powder, boron powder and red phosphorus powder (the particle size is 80-150 meshes), uniformly mixing, and spreading on a steel plate with the spreading thickness of 5 mm;

(2) after the steel plate is placed into a steel box, sealed and vacuumized, the steel plate is subjected to heat preservation in a furnace at the temperature of 840-930 ℃ for 2-5 hours to carry out in-situ reaction between gas (P) -liquid (Al) and liquid (Al) -solid (B), and a blocky Al-B-P composite modifier is prepared;

(3) taking out the blocky Al-B-P composite modifier, and crushing the blocky Al-B-P composite modifier into 1-3 mm.

Preferably, the alloy in the step (1) comprises the following components: 1.0-8.0% of B, 2.5-10.0% of P, and the balance of aluminum.

The invention relates to a component design of an Al-B-P composite modifier according to an Al-B-P ternary system 700 ℃ isothermal cross section related system, which comprises the following specific components of 0.5-15.0% of B, 0.5-15.0% of P and the balance of phase compositions of Al-B-P alloy of α -Al and AlB₂And AlP, AlB₂And the AlP phase is uniformly distributed in an α -Al matrix, and the composite modification treatment of the eutectic aluminum-silicon alloy by adopting the Al-B-P dual modifier can improve the modification efficiency.

The principle of the invention is as follows:

according to the 700 ℃ isothermal cross section phase relation of the Al-B-P ternary system, α -Al + AlB exists₂+ AlP three-phase region, Al-B-P intermediate alloy is designed in this region, and the phase composition of the alloy is α -Al and AlB₂And an AlP phase. When aluminum powder, boron powder and red phosphorus powder with the particle size of 80-150 meshes are uniformly mixed, liquid aluminum and gaseous phosphorus, and liquid aluminum and solid boron are subjected to in-situ reaction at 840-930 ℃, and aluminum element and boron and phosphorus element respectively undergo in-situ reaction to generate AlB₂And AlP phases, these resulting phases will be uniformly distributed in the aluminum matrix. AlB₂The phase can be used as a nucleation particle of α -Al phase, and the AlP phase can be used as a nucleation particle of silicon phase, so that the Al-B-P alloy can play a double-modification role in the aluminum-silicon alloy.

The invention has the beneficial effects that:

the Al-B-P intermediate alloy prepared by the invention has AlB in the alloy structure₂And an AlP phase, and is uniformly distributed in the alloy matrix, has obvious dual modification effect on the eutectic aluminum-silicon alloy, and has better industrial application prospect.

Drawings

The invention is further described below with reference to the figures and examples.

FIG. 1 is a 700 ℃ isothermal cross-sectional phase relationship of an Al-B-P ternary system.

FIG. 2 is an X-ray diffraction pattern of the Al-1.5B-3P master alloy prepared in example 1.

FIG. 3 is a microstructure of the Al-1.5B-3P master alloy prepared in example 1.

FIG. 4 is the microstructure of the Al-2.5B-2.5P master alloy prepared in example 2.

FIG. 5 is the microstructure of the Al-4.0B-10P master alloy prepared in example 3.

FIG. 6 is the microstructure of the Al-8.0B-8.0P master alloy prepared in example 4.

FIG. 7 shows the microstructure of the modified eutectic Al-Si alloy of the Al-1.5B-3P master alloy of example 5.

Detailed Description

The present invention will be described in more detail by way of examples, but the scope of the present invention is not limited to these examples.

Example 1

(1) Uniformly mixing aluminum powder, boron powder and red phosphorus powder (the mass percentage is that boron is 1.5 percent, phosphorus is 3.0 percent and aluminum is 95.5 percent), and then spreading the mixture on a steel plate, wherein the thickness of the mixed powder is 5 mm;

(2) after the steel plate is placed into a steel box, sealed and vacuumized, the steel plate is kept in a furnace at 850 ℃ for 2.5 hours to carry out in-situ reaction between liquid aluminum and gaseous phosphorus and between liquid aluminum and solid boron to prepare a blocky Al-1.5B-3.0P composite modifier;

(3) taking out the Al-1.5B-3.0P composite modifier, and crushing the modifier into 1-3 mm.

As shown in the X-ray diffraction pattern of the Al-1.5B-3P master alloy shown in FIG. 2, the phase composition of the master alloy is α -Al and AlB₂And an AlP phase. As can be seen from the Al-1.5B-3P master alloy microstructure shown in FIG. 3, AlB₂And the AlP phase is uniformly distributed in the α -Al matrix.

Example 2

(1) Uniformly mixing aluminum powder, boron powder and red phosphorus powder (the mass percentage is that boron is 2.5 percent, phosphorus is 2.5 percent and aluminum is 95.0 percent), and then spreading the mixture on a steel plate, wherein the thickness of the mixed powder is controlled to be 5 mm;

(2) after the steel plate is placed into a steel box for sealing and vacuumizing, the steel plate is kept warm for 3 hours in a furnace at 870 ℃ to carry out in-situ reaction between liquid aluminum and gaseous phosphorus and between the liquid aluminum and solid boron to prepare a blocky Al-2.5B-2.5P composite modifier;

(3) taking out the Al-2.5B-2.5P composite modifier, and crushing the modifier into 1-3 mm.

As can be seen from the Al-2.5B-2.5P master alloy microstructure shown in FIG. 4, AlB₂And the AlP phase is uniformly distributed in the α -Al matrix.

Example 3

(1) Uniformly mixing aluminum powder, boron powder and red phosphorus powder (the mass percentage is 4.0 percent of boron, 10.0 percent of phosphorus and 86.0 percent of aluminum), and then spreading the mixture on a steel plate, wherein the thickness of the mixed powder is controlled to be 5 mm;

(2) after the steel plate is placed into a steel box, sealed and vacuumized, the steel plate is kept in a 890 ℃ furnace for 3.5 hours to carry out in-situ reaction between liquid aluminum and gaseous phosphorus, and between the liquid aluminum and solid boron, so as to prepare a massive Al-4.0B-10.0P composite modifier;

(3) taking out the Al-4.0B-10.0P composite modifier, and crushing the modifier into 1-3 mm.

As can be seen from the Al-4.0B-10.0P master alloy microstructure shown in FIG. 5, AlB₂And the AlP phase is uniformly distributed in the α -Al matrix.

Example 4

(1) Uniformly mixing aluminum powder, boron powder and red phosphorus powder (the mass percentage is 8.0 percent of boron, 8.0 percent of phosphorus and 84.0 percent of aluminum), and then spreading the mixture on a steel plate, wherein the thickness of the mixed powder is controlled to be 5 mm;

(2) after the steel plate is placed into a steel box, sealed and vacuumized, the steel plate is kept in a furnace at the temperature of 920 ℃ for 4 hours to carry out in-situ reaction, and a blocky Al-8.0B-8.0P composite modifier is prepared;

(3) taking out the Al-8.0B-8.0P composite modifier, and crushing the modifier into 1-3 mm.

As can be seen from the Al-8.0B-8.0P master alloy microstructure shown in FIG. 6, AlB₂And the AlP phase is uniformly distributed in the α -Al matrix.

Example 5

The Al-1.5B-3.0P alterant prepared in the example 1 is adopted to carry out composite modification treatment on the eutectic aluminum-silicon alloy:

(1) smelting eutectic aluminum-silicon alloy in a graphite crucible by using a well-type electric furnace;

(2) adding hexachloroethane for degassing and refining;

(3) quickly pressing the Al-1.5B-3.0P alterant into the melt, uniformly stirring and then preserving heat;

(4) and pouring the melt into a preheated metal mold to obtain the eutectic aluminum-silicon alloy with double metamorphism.

As can be seen from the microstructure of the Al-1.5B-3P master alloy modified eutectic aluminum-silicon alloy shown in FIG. 7, the area fraction of alpha-Al is the largest and the size of dendrite is the smallest, fine primary crystal Si is uniformly distributed in the matrix, and most eutectic silicon is converted into particles. The above phenomena indicate that the eutectic aluminum silicon microstructure prepared in example 5 is at a good level.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A preparation method of an Al-B-P dual modifier for eutectic aluminum-silicon alloy is characterized in that the Al-B-P alloy comprises 0.5-15.0% of B, 0.5-15.0% of P and the balance of Al in percentage by mass, the Al-B-P alloy is prepared by respectively weighing aluminum powder, boron powder and red phosphorus powder with the granularity of 80-150 meshes, uniformly mixing the aluminum powder, the boron powder and the red phosphorus powder, spreading the mixture on a steel plate, placing the steel plate into a steel box, sealing and vacuumizing the steel plate, and then preserving the heat of the steel plate in a furnace at 840-930 ℃ for 2-5 hours to perform gas-liquid and liquid-solid in-situ reaction to prepare a blocky Al-B-P composite modifier, and the phase composition of the Al-B-P alloy is α -Al and AlB₂And AlP; AlB₂And the AlP phase is uniformly distributed in the α -Al matrix.

2. The method of preparing an Al-B-P dual inoculant for eutectic aluminum-silicon alloy according to claim 1, wherein: the Al-B-P alloy comprises the following components: 1.0-8.0% of B, 2.5-10.0% of P, and the balance of Al.

3. The method of preparing an Al-B-P dual inoculant for eutectic aluminum-silicon alloy according to claim 1, wherein: the thickness of a flat laying layer of mixed powder consisting of aluminum powder, boron powder and red phosphorus powder is 5 mm.

4. The method of preparing an Al-B-P dual inoculant for eutectic aluminum-silicon alloy according to claim 1, wherein: generating the Al-B-P composite modifier through in-situ reaction between gaseous phosphorus and liquid aluminum and between liquid aluminum and solid boron at 840-930 ℃, and then crushing into particles of 1-3 mm.

5. Use of the Al-B-P dual inoculant for the preparation of a eutectic aluminum silicon alloy according to any one of the claims 1 to 4, wherein the Al-B-P alloy is used for the composite inoculant treatment of eutectic aluminum silicon alloys.